Thermal and Temperature

Anderson, N.L., T.E. Hetherington, B. Coupe, G. Perry, J.B. Williams, and J. Lehman (2005). Thermoregulation in a nocturnal, tropical, arboreal snake. Journal of Herpetology 39(1): 82-90. ISSN: 0022-1511.
NAL Call Number: QL640.J6
Descriptors: reptiles, arboreal snake, nocturnal, tropical, thermoregulation, Boiga irregularis, brown tree snakes.

Angilletta, M.J.J., V. Lee, and A.C. Silva (2006). Energetics of lizard embryos are not canalized by thermal acclimation. Physiological and Biochemical Zoology 79(3): 573-580. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: In some species of ectotherms, temperature has little or no effect on the amount of energy expended during embryonic development. This phenomenon can result from either of two mechanisms: (1) a shorter incubation period at higher temperatures, which offsets the expected increase in metabolic rate, or (2) a compensatory decrease in the rate at which embryos expend energy for maintenance. To distinguish the relative importance of these two mechanisms, we quantified the acute and chronic effects of temperature on embryonic metabolism in the eastern fence lizard (Sceloporus undulatus). First, we measured metabolic rates of individual embryos at 27 degrees, 31 degrees, and 34 degrees C. Second, we examined the capacity for thermal acclimation by measuring the metabolic rates of embryos at 30 degrees C, after a period of incubation at either 28 degrees or 32 degrees C. As with adult reptiles, the metabolic rates of embryos increased with an acute increase in temperature; the Q(10) of metabolic rate from 27 degrees to 34 degrees C was 2.1 (+/-0.2). No evidence of thermal acclimation was observed either early or late in development. In S. undulatus, a shorter incubation period at higher temperatures appears to play the primary role in canalizing the energy budget of an embryo, but a reduction in the cost of growth could play a secondary role.
Descriptors: lizards, acclimatization physiology, embryonic development physiology, lizards embryology, lizards physiology, basal metabolism physiology, embryo, non-mammalian physiology, oviparity physiology, temperature.

Blouin Demers, G. and P. Nadeau (2005). The cost-benefit model of thermoregulation does not predict lizard thermoregulatory behavior. Ecology 86(3): 560-566. ISSN: 0012-9658.
Descriptors: reptiles, lizard, thermoregulation, thermoregulatory behavior, cost benefit model, temperature.

Booth, D.T. (2006). Influence of incubation temperature on hatchling phenotype in reptiles. Physiological and Biochemical Zoology 79(2): 274-281. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: Incubation temperature influences hatchling phenotypes such as sex, size, shape, color, behavior, and locomotor performance in many reptiles, and there is growing concern that global warming might adversely affect reptile populations by altering frequencies of hatchling phenotypes. Here I overview a recent theoretical model used to predict hatchling sex of reptiles with temperature-dependent sex determination. This model predicts that sex ratios will be fairly robust to moderate global warming as long as eggs experience substantial daily cyclic fluctuations in incubation temperatures so that embryos are exposed to temperatures that inhibit embryonic development for part of the day. I also review studies that examine the influence of incubation temperature on posthatch locomotion performance and growth because these are the traits that are likely to have the greatest effect on hatchling fitness. The majority of these studies used artificial constant-temperature incubation, but some have addressed fluctuating incubation temperature regimes. Although the number of studies is small, it appears that fluctuating temperatures may enhance hatchling locomotor performance. This finding should not be surprising, given that the majority of natural reptile nests are relatively shallow and therefore experience daily fluctuations in incubation temperature.
Descriptors: reptiles, newborn anatomy, histology, growth, development, reptiles anatomy, histology, growth, development, temperature, physiology, greenhouse effect, ovum physiology.

Booth, D.T., E. Burgess, J. McCosker, and J.M. Lanyon (2005). The influence of incubation temperature on post-hatching fitness characteristics of turtles. In: Animals and environments: Proceedings of the Third International Conference of Comparative Physiology and Biochemistry,August 7, 2004-August 13, 2004, KwaZulu-Natal, South Africa, International Congress Series, 0531-5131, Elsevier: Amsterdam, p. 226-233. ISBN: 0444517634.
NAL Call Number: QP82 .I58 2004
Descriptors: reptiles, turtles, incubation temperature, post hatching fitness, development.

Bostrom, B.L. and D.R. Jones (2007). Exercise warms adult leatherback turtles. Comparative Biochemistry and Physiology. Part A, Molecular and Integrative Physiology 147(2): 323-331. ISSN: 1095-6433.
Abstract: Leatherback sea turtles (Dermochelys coriacea) can maintain body temperature (T(B)) up to 18 degrees C above that of the surrounding sea water (T(W)) which allows leatherbacks to enter cold temperate waters and have the largest global range of any reptile. Using a cylindrical model of a leatherback we investigated the extent to which heat production through variation of swim speed could be used in a leatherback's thermal strategy. Drag force of a full scale cast of a leatherback was measured in a low velocity wind tunnel to obtain an estimate of the metabolic cost needed to offset drag. Heat released in the core of a turtle as a byproduct of the metabolic cost of locomotion is conducted from the core of the turtle to the surrounding water through its insulation layer. By keeping insulation thickness constant, we highlight the effectiveness of swim speed in maintaining T(B)-T(W). Our model, when tested against published data at a given T(W), showed a close correlation between predicted and measured swimming speed at a given T(B). We conclude that the ability to maintain a large T(B)-T(W) is an interplay between mass, insulation thickness and water temperature selection but behavioural control of swimming speed predominates.
Descriptors: reptiles, leatherback sea turtles, body temperature, maintain, swim speed, drag force, body insulation thickness.

Bradshaw, D., M. Ladyman, and T. Stewart (2007). Effect of hypernatraemia and the neurohypophysial peptide, arginine vasotocin (AVT) on behavioural thermoregulation in the agamid lizard, Ctenophorus ornatus. General and Comparative Endocrinology 150(1): 34-40. ISSN: 0016-6480.
NAL Call Number: 444.8 G28
Abstract: Hypernatraemia induced by chronic injections of sodium chloride provokes thermal depression in the agamid lizard, Ctenophorus (formerly Amphibolurus) ornatus, with a fall of two degrees Celsius in the mean body temperature selected behaviourally in a photo-thermal gradient. The placement of an electrolytic lesion in the base of the hypothalamus, designed to eliminate secretion of the neuropeptide arginine vasotocin (AVT), did not affect the lizards' thermoregulatory behaviour and their Preferred Body Temperature (PBT) was not significantly different from that of unoperated controls. Saline loading, however, did not induce thermal depression in these tract-operated individuals and their PBT was significantly higher than that of salt-loaded intact individuals. When AVT was injected into operated, salt-loaded, animals, however, thermal depression was observed, supporting the hypothesis that thermal depression brought about by hypernatraemia is mediated through the action of AVT. AVT similarly significantly depressed the PBT of injected intact individuals by 3.2 degrees C when compared with hydrated controls. Immunostaining for AVT confirmed that the lesions placed in the region of the median eminence virtually eliminated AVT located in the neurohypophysial tract, and the pars nervosa. This is the first report of an effect of this peptide on behavioural thermoregulation in a lizard.
Descriptors: reptiles, agamid lizard, hypernatrimia, effects, neurohpophysial peptide, arginine vasotocin, behavioral thermoregulation.

Chen, H.L. and X. Ji (2002). The effects of thermal environments on duration of incubation, hatching success and hatchlings traits in a colubrid snake, Rhabdophis tigrinus lateralis (Boie). Acta Ecologica Sinica 22(11): 1850-1858. ISSN: 1000-0933.
Descriptors: reptiles, colubrid snake, Rhabdophis tigrinus lateralis, thermal environments, effects. incubation duration, hatching success, hatching traits.
Language of Text: Chinese; Summary in Chinese and English.

Chiara Magnone, M., B. Jacobmeier, C. Bertolucci, A. Foa, and U. Albrecht (2005). Circadian expression of the clock gene Per2 is altered in the ruin lizard (Podarcis sicula) when temperature changes. Brain Research. Molecular Brain Research 133(2): 281-285. ISSN: 0169-328X.
Abstract: When exposed to the cold, the body temperature of the ruin lizard (Podarcis sicula), an ectothermic vertebrate, comes into equilibrium with that low environmental temperature. During this time, the behavioral output of the circadian clock, locomotor activity, disappears. We tested the activity of the circadian clockwork at low temperature (6 degrees C) by following the expression of one of its essential components, the Period2 (Per2) gene. Here we show that lizard Per2 (lPer2) expression, which is rhythmic and paralleling the behavioral rhythm of locomotor activity at higher temperature (29 degrees C), becomes constantly high at low temperature. When lizards are re-exposed to high temperature, rhythmic lPer2 expression is re-established after 2 days of adaptation and coincides with onset of locomotor activity. The alteration of the lPer2 expression pattern at low temperature indicates that the activity of the molecular feedback loop is modified under these conditions.
Descriptors: lizard, Podarcis sicula, circadian rhythm, temperature, eye proteins genetics, RNA, biosynthesis, reverse transcriptase polymerase chain reaction methods.

Christian, K.A., C.R. Tracy, and C.R. Tracy (2006). Evaluating thermoregulation in reptiles: An appropriate null model. American Naturalist 168(3): 421-430. ISSN: 0003-0147.
NAL Call Number: 470 Am36
Descriptors: reptiles, thermoregulation, evaluating, null model, ectotherms, thermal inertia, body mass, warming, cooling.

Clark, T.D., P.J. Butler, and P.B. Frappell (2005). Digestive state influences the heart rate hysteresis and rates of heat exchange in the varanid lizard Varanus rosenbergi. Journal of Experimental Biology 208(Pt 12): 2269-2276. ISSN: 0022-0949.
Online: http://dx.doi.org/10.1242/jeb.01657
NAL Call Number: 442.8 B77
Abstract: To maximize the period where body temperature (Tb) exceeds ambient temperature (Ta), many reptiles have been reported to regulate heart rate (fH) and peripheral blood flow so that the rate of heat gain in a warming environment occurs more rapidly than the rate of heat loss in a cooling environment. It may be hypothesized that the rate of cooling, particularly at relatively cool Tbs, would be further reduced during postprandial periods when specific dynamic action (SDA) increases endogenous heat production (i.e. the heat increment of feeding). Furthermore, it may also be hypothesized that the increased perfusion of the gastrointestinal organs that occurs during digestion may limit peripheral blood flow and thus compromise the rate of heating. Finally, if the changes in fh are solely for the purpose of thermoregulation, there should be no associated changes in energy demand and, consequently, no hysteresis in the rate of oxygen consumption (V(O2)). To test these hypotheses, seven individual Varanus rosenbergi were heated and cooled between 19 degrees C and 35 degrees C following at least 8 days fasting and then approximately 25 h after consumption of a meal (mean 10% of fasted body mass). For a given Tb between the range of 19-35 degrees C, fh of fasting lizards was higher during heating than during cooling. Postprandial lizards also displayed a hysteresis in fh, although the magnitude was reduced in comparison with that of fasting lizards as a result of a higher fh during cooling in postprandial animals. Both for fasting and postprandial lizards, there was no hysteresis in V(O2) at any Tb throughout the range although, as a result of SDA, postprandial animals displayed a significantly higher V(O2) than fasting animals both during heating and during cooling at Tbs above 24 degrees C. The values of fh during heating at a given Tb were the same for fasting and postprandial animals, which, in combination with a slower rate of heating in postprandial animals, suggests that a prioritization of blood flow to the gastrointestinal organs during digestion is occurring at the expense of higher rates of heating. Additionally, postprandial lizards took longer to cool at Tbs below 23 degrees C, suggesting that the endogenous heat produced during digestion temporarily enhances thermoregulatory ability at lower temperatures, which would presumably assist V. rosenbergi during cooler periods in the natural environment by augmenting temperature-dependent physiological processes.
Descriptors: lizard, Varanus rosenbergi, body temperature regulation, digestive system, gastrointestinal tract, blood supply, heart rate, postprandial period, body temperature, electrocardiography, oxygen consumption.

Clark, T.D., T. Wang, P.J. Butler, and P.B. Frappell (2005). Factorial scopes of cardio-metabolic variables remain constant with changes in body temperature in the varanid lizard, Varanus rosenbergi. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 288(4): R992-R997. ISSN: print: 0363-6119; online: 1522-1490.
Online: http://dx.doi.org/10.1152/ajpregu.00593.2004
Abstract: The majority of information concerning the cardio-metabolic performance of varanids during exercise is limited to a few species at their preferred body temperature (T(b)) even though, being ectotherms, varanids naturally experience rather large changes in T(b). Although it is well established that absolute aerobic scope declines with decreasing T(b), it is not known whether changes in cardiac output (V(b)) and/or tissue oxygen extraction, (Ca(O2) - Cv(O2)), are in proportion to the rate of oxygen consumption (Vo(2)). To test this, we studied six Rosenberg's goannas (Varanus rosenbergi) while at rest and while maximally exercising on a treadmill both at 25 and 36 degrees C. During maximum exercise both at 25 and 36 degrees C, mass-specific rate of oxygen consumption (Vo(2kg)) increased with an absolute scope of 8.5 ml min(-1) kg(-1) and 15.7 ml min(-1) kg(-1), respectively. Interestingly, the factorial aerobic scope was temperature-independent and remained at 7.0 which, at each T(b), was primarily the result of an increase in V(bkg), governed by approximate twofold increases both in heart rate (f(H)) and cardiac stroke volume (V(Skg)). Both at 25 degrees C and 36 degrees C, the increase in V(bkg) alone was not sufficient to provide all of the additional oxygen required to attain maximal Vo(2kg), as indicated by a decrease in the blood convection requirement V(bkg)/Vo(2kg); hence, there was a compensatory twofold increase in (Ca(O2) - Cv(O2)). Although associated with an increase in hemoglobin-oxygen affinity, a decrease in T(b) did not impair unloading of oxygen at the tissues and act to reduce (Ca(O2) - Cv(O2)); both Ca(O2)) and Cv(O2)) were maintained across T(b). The change in Vo(2kg) with T(b), therefore, is solely reliant on the thermal dependence of V(bkg). Maintaining a high factorial aerobic scope across a range of T(b) confers an advantage in that cooler animals can achieve higher absolute aerobic scopes and presumably improved aerobic performance than would otherwise be achievable.
Descriptors: varanid lizard, body temperature, physiology, hemodynamic processes, metabolism, blood gas analysis, cardiac output, exertion, heart rate, oxygen consumption, seasons, temperature.

Clusella Trullas, S., J.S. Terblanche, J.H. van Wyk, and J.R. Spotila (2007). Low repeatability of preferred body temperature in four species of Cordylid lizards: Temporal variation and implications for adaptive significance. Evolutionary Ecology 21(1): 63-79. ISSN: 0269-7653.
Abstract: Preferred body temperatures (T sel) of ectotherms are important for ecological and evolutionary studies. In lizards, the measurement of T sel is controversial for several reasons, generally related to hypotheses addressing how T sel may evolve in the wild. Although seldom explicitly tested, evolutionary hypotheses of adaptation to local climate require that T sel meets the conditions of natural selection, which include repeatability, heritability and a link to fitness. Here, we investigated repeatability ((Sx(B, intra-class correlation coefficient) of T sel at several time-scales using four Cordylid species from heterogeneous thermal habitats. Although there was significant inter-individual variation within days (P < 0.005 in most cases), there was no significant inter-individual variation when calculated across several days (P > 0.05). Repeatability was low in all species investigated (from 0 to 0.482) when compared against other estimates of repeatability of T sel in the literature. Irrespective of how T sel was calculated, it showed inconsistent and variable temporal effects across species. Furthermore, repeatability of T sel did not change with acclimation to laboratory conditions. These data have implications for understanding the evolution of thermoregulation in these and other ectotherms.
Descriptors: reptiles, Cordylus, lizards, thermoregulation, coadaptation, inter individual variation, selection, temporal effects.

Costanzo, J.P., P.J. Baker, and R.E.J. Lee (2006). Physiological responses to freezing in hatchlings of freeze-tolerant and -intolerant turtles. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 176(7): 697-707. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: Freeze tolerance is a complex cold-hardiness adaptation that has independently evolved in a diverse group of organisms, including several ectothermic vertebrates. Because little is known about the mechanistic basis for freeze tolerance in reptiles, we compared responses to experimental freezing in winter-acclimatized hatchlings representing nine taxa of temperate North American turtles, including ones that tolerated freezing and others that did not. Viability rates of hatchlings frozen to -3 degrees C for 72 h ranged from 0 to 100%. Tolerance to freezing was poor in Sternotherus odoratus, Graptemys geographica and Trachemys scripta, intermediate in Chelydra serpentina, and high in Emydoidea blandingii, Chrysemys picta bellii, C. p. marginata, Malaclemys terrapin, and Terrapene ornata, and generally reflected the winter thermal ecology of each taxon. Plasma activity of lactate dehydrogenase (LDH), a novel in vivo index of freeze/thaw damage, corroborated viability assessments and demonstrated that cryoinjury occurred even in surviving turtles. Irrespective of taxon, cryoinjury tended to be higher in smaller individuals and in those having relatively low water contents; however, bases for these associations were not apparent. Screening for certain organic osmolytes that might promote freezing survival by colligatively reducing ice content and limiting cell dehydration showed that the plasma of unfrozen (control) turtles contained small quantities of glucose (1.3-5.8 mmol l(-1)) and lactate (0.6-3.2 mmol l(-1)) and modest amounts of urea (range of mean values for all taxa 8.2-52.3 mmol l(-1)). Frozen/thawed turtles of all taxa accumulated modest amounts of glucose and lactate that jointly raised the plasma solute concentration by 30-100 mmol l(-1). We conclude that organic osmolytes accumulated both before and during freezing may promote survival in species that have evolved a tolerance to freezing, but are not necessarily accumulated for that purpose.
Descriptors: turtles adaptation, physiological, freezing, physiology, cryoprotective agents, osmolar concentration, Noth American species.

Cowles, R.B. and C.M. Bogert (2006). Preliminary study of the thermal requirements of desert reptiles. Iguana 13(1): 53-60. ISSN: 1554-916X.
Descriptors: reptiles, desert reptiles, thermal requirements, preliminary study.

Crews, D., S. Partesotti, R. Porter, M. Ramsey, J.K. Skipper, and M. Wu (2003). Physiology of temperature-dependent sex determination in reptiles. SICB Annual Meeting and Exhibition Final Program and Abstracts 2003: 145-146. ISSN: print: 1540-7063; online: 1557-7023.
Descriptors: reptiles, sex determination, temperature, physiology, meeting abstracts.
Notes: Meeting Information: Annual Meeting and Exhibition of the SICB (Society for Integrative and Comparative Biology), Toronto, ON, Canada; January 04-08, 2003.

DeNardo, D.F. (2004). Understanding and meeting the thermal needs of the reptile patient. Small Animal and Exotics Book Two: Pain Management Zoonosis Proceedings of the North American Veterinary Conference, Volume 18 18: 1323-1325. ISSN: 0341-6593.
Descriptors: reptile patient, thermal needs, conference proceedings, book chapter.

Diaz, J.A. and S. Cabezas Diaz (2004). Seasonal variation in the contribution of different behavioural mechanisms to lizard thermoregulation. Functional Ecology 18(6): 867-875. ISSN: 0269-8463.
NAL Call Number: QH540.F85
Descriptors: reptiles, lizard, thermoregulation, behavioral mechanisms, seasonal variation, temperature.

Diaz, J.A., P. Iraeta, and C. Monasterio (2006). Seasonality provokes a shift of thermal preferences in a temperate lizard, but altitude does not. Journal of Thermal Biology 31(3): 237-242. ISSN: 0306-4565.
NAL Call Number: QP82.2.T4J6
Descriptors: reptiles, temperate lizard, thermal preferences, seasonality, altitude, provokes, shift, thermal range.

Dinkelacker, S.A., J.P. Costanzo, and R.E.J. Lee (2005). Anoxia tolerance and freeze tolerance in hatchling turtles. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 175(3): 209-217. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: Freezing survival in hatchling turtles may be limited by ischemic anoxia in frozen tissues and the associated accumulation of lactate and reactive oxygen species (ROS). To determine whether mechanisms for coping with anoxia are also important in freeze tolerance, we examined the association between capacities for freezing survival and anoxia tolerance in hatchlings of seven species of turtles. Tolerance to freezing (-2.5 degrees C) was high in Emydoidea blandingii, Chrysemys picta, Terrapene ornata, and Malaclemys terrapin and low in Graptemys geographica, Chelydra serpentina, and Trachemys scripta. Hatchlings survived in a N(2) atmosphere at 4 degrees C for periods ranging from 17 d (M. terrapin) to 50 d (G. geographica), but survival time was not associated with freeze tolerance. Lactate accumulated during both stresses, but plasma levels in frozen/thawed turtles were well below those found in anoxia-exposed animals. Activity of the antioxidant enzyme catalase in liver increased markedly with anoxia exposure in most species, but increased with freezing/thawing only in species with low freeze tolerance. Our results suggest that whereas oxygen deprivation occurs during somatic freezing, freeze tolerance is not limited by anoxia tolerance in hatchling turtles.
Descriptors: turtles, acclimatization, physiology, anoxia, catalase metabolism, freezing, lactates, blood, liver anatomy, histology, enzymology, organ size, oxidative stress.

do Amaral, J.P., G.A. Marvin, and V.H. Hutchison (2002). The influence of bacterial lipopolysaccharide on the thermoregulation of the box turtle Terrapene carolina. Physiological and Biochemical Zoology 75(3): 273-282. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: Ectotherms can adjust their thermoregulatory set points in response to bacterial infection; the result may be similar to endothermic fever. We examined the influence of dose on the set point of body temperature (T(b)) in Terrapene carolina. After acclimating postprandial turtles to 20 degrees C, we injected them with two doses of bacterial endotoxin (LPS; lipopolysaccharide from Escherichia coli), 0.0025 or 0.025 mg LPS/g nonshell body mass, or with reptilian saline (control group). We placed the animals singly in linear thigmothermal gradients and recorded their T(b)'s for 48 h. The turtles showed dose-influenced thermal selection. Turtles injected with the high dose had T(b)'s significantly higher than control turtles, whereas low-dose turtles had T(b)'s significantly lower than control turtles. Also, there was a low daily effect on the T(b) of the turtles injected with the high dose. High-dose turtles had significantly higher T(b)'s than the control turtles during the first day but not during the second. Our results support the prediction of Romanovsky and Szekely that an infectious agent may elicit opposite thermoregulatory responses depending on quality and quantity of the agent and the host health status.
Descriptors: reptiles, captive box turtle, Terrapene carolina, thermoregulation, bacterial lipopolysaccharide, influence, body temperature, postprandial.

Do Amaral, J.P.S., G.A. Marvin, and V.H. Hutchison (2002). Thermoregulation in the box turtles Terrapene carolina and Terrapene ornata. Canadian Journal of Zoology 80(5): 934-943. ISSN: 0008-4301.
NAL Call Number: 470 C16D
Descriptors: reptiles, box turtles, Terrapene carolina and Terrapene ornata, thermoregulation, habitats, desert, forest, differences, body temperature.

Drake, D.L. and J.R. Spotila (2002). Thermal tolerances and the timing of sea turtle hatchling emergence. Journal of Thermal Biology 27(1): 71-81. ISSN: 0306-4565.
NAL Call Number: QP82.2.T4J6
Descriptors: reptiles, sea turtle, hatchling emergence, thermal tolerances, sand temperatures.

Du, W.G. and X. Ji (2006). Effects of constant and fluctuating temperatures on egg survival and hatchling traits in the northern grass lizard (Takydromus septentrionalis, Lacertidae). Journal of Experimental Zoology. Part A, Comparative Experimental Biology 305(1): 47-54. ISSN: print: 1548-8969; online: 1552-499X.
NAL Call Number: QL1.J854
Abstract: To understand how nest temperatures influence phenotypic traits of reptilian hatchlings, the effects of fluctuating temperature on hatchling traits must be known. Most investigations, however, have only considered the effects of constant temperatures. We incubated eggs of Takydromus septentrionalis (Lacertidae) at constant (24 degrees C, 27 degrees C, 30 degrees C and 33 degrees C) and fluctuating temperatures to determine the effects of these thermal regimes on incubation duration, hatching success and hatchling traits (morphology and locomotor performance). Hatching success at 24 degrees C and 27 degrees C was higher, and hatchlings derived from these two temperatures were larger and performed better than their counterparts from 30 degrees C and 33 degrees C. Eggs incubated at fluctuating temperatures exhibited surprisingly high hatching success and also produced large and well-performed hatchlings in spite of the extremely wide range of temperatures (11.6-36.2 degrees C) they experienced. This means that exposure of eggs to adversely low or high temperatures for short periods does not increase embryonic mortality. The variance of fluctuating temperatures affected hatchling morphology and locomotor performance more evidently than did the mean of the temperatures in this case. The head size and sprint speed of the hatchlings increased with increasing variances of fluctuating temperatures. These results suggest that thermal variances significantly affect embryonic development and phenotypic traits of hatchling reptiles and are therefore ecologically meaningful.
Descriptors: grass lizard, Takydromus septentrionalis, body constitution, energy metabolism, lizards growth and development, locomotion, temperature, physiological adaptation, newborn animals, embryonic development.

Du, W.G. and X. Ji (2002). Effects of incubation temperature on duration of incubation. Hatching success, and hatching traits in the gray rat snake, Ptyas korros (Colubridae). Acta Ecologica Sinica 22(4): 548-553. ISSN: 1000-0933.
Descriptors: reptiles, gray rat snake, Ptyas korros, incubation temperature, duration of incubation, hatching success.
Language of Text: Chinese; Summary in Chinese and English.

Ellis, D.J., B.T. Firth, and I. Belan (2006). Circadian rhythm of behavioral thermoregulation in the sleepy lizard (Tiliqua rugosa). Herpetologica 62(3): 259-265. ISSN: 0018-0831.
NAL Call Number: QL640.H4
Descriptors: reptiles, sleepy lizard, Tiliqua rugosa, circadian rhythm, behavioral thermoregulation, body temperature, photoperiod, seasonal variation.

Franklin, C.E. and F. Seebacher (2003). The effect of heat transfer mode on heart rate responses and hysteresis during heating and cooling in the estuarine crocodile Crocodylus porosus. Journal of Experimental Biology. 206(Pt 7): 1143-1151. ISSN: 0022-0949.
Online: http://dx.doi.org/10.1242/jeb.00222
NAL Call Number: 442.8 B77
Abstract: The effect of heating and cooling on heart rate in the estuarine crocodile Crocodylus porosus was studied in response to different heat transfer mechanisms and heat loads. Three heating treatments were investigated. C. porosus were: (1) exposed to a radiant heat source under dry conditions; (2) heated via radiant energy while half-submerged in flowing water at 23 degrees C and (3) heated via convective transfer by increasing water temperature from 23 degrees C to 35 degrees C. Cooling was achieved in all treatments by removing the heat source and with C. porosus half-submerged in flowing water at 23 degrees C. In all treatments, the heart rate of C. porosus increased markedly in response to heating and decreased rapidly with the removal of the heat source. Heart rate during heating was significantly faster than during cooling at any given body temperature, i.e. there was a significant heart rate hysteresis. There were two identifiable responses to heating and cooling. During the initial stages of applying or removing the heat source, there was a dramatic increase or decrease in heart rate ('rapid response'), respectively, indicating a possible cardiac reflex. This rapid change in heart rate with only a small change or no change in body temperature (<0.5 degrees C) resulted in Q(10) values greater than 4000, calling into question the usefulness of this measure on heart rate during the initial stages of heating and cooling. In the later phases of heating and cooling, heart rate changed with body temperature, with Q(10) values of 2-3. The magnitude of the heart rate response differed between treatments, with radiant heating during submergence eliciting the smallest response. The heart rate of C. porosus outside of the 'rapid response' periods was found to be a function of the heat load experienced at the animal surface, as well as on the mode of heat transfer. Heart rate increased or decreased rapidly when C. porosus experienced large positive (above 25 W) or negative (below -15 W) heat loads, respectively, in all treatments. For heat loads between -15 W and 20 W, the increase in heart rate was smaller for the 'unnatural' heating by convection in water compared with either treatment using radiant heating. Our data indicate that changes in heart rate constitute a thermoregulatory mechanism that is modulated in response to the thermal environment occupied by the animal, but that heart rate during heating and cooling is, in part, controlled independently of body temperature.
Descriptors: reptiles, estuarine crocodile, Crocodylus porosus, heat transfer mode, heart rate response, effect, hysteresis, heating, cooling, body temperature.

Galli, G., E.W. Taylor, and T. Wang (2004). The cardiovascular responses of the freshwater turtle Trachemys scripta to warming and cooling. Journal of Experimental Biology. 207(Pt 9): 1471-1478. ISSN: 0022-0949.
Online: http://dx.doi.org/10.1242/jeb.00912
NAL Call Number: 442.8 B77
Abstract: Seven freshwater turtles Trachemys scripta were instrumented with flow probes and cannulated for blood pressure measurements. The turtles were warmed from 24 to 34 degrees C, and cooled down to 24 degrees C, with and without atropine. Animals exhibited a hysteresis of heart rate and blood flow to both the pulmonary and systemic circulations, which was not cholinergically mediated. Blood pressure remained constant during both warming and cooling, while systemic resistance decreased during heating and increased during cooling, indicating a barostatic response. There was a large right-to-left (R-L) shunt during warming and cooling in untreated animals, which remained relatively constant. Atropinisation resulted in a large L-R shunt, which decreased during warming and increased during cooling. Nevertheless, heating rates were the same in untreated and atropinised animals, and cooling rates were significantly longer in atropinised animals, indicating that shunt patterns contribute little to heat exchange.
Descriptors: reptiles, freshwater turtle, Trachemys scripta, cardiovascular responses, warming, cooling, atropine, blood pressure, body temperature, shunt.

Georges, A., K. Beggs, J.E. Young, and J.S. Doody (2005). Modelling development of reptile embryos under fluctuating temperature regimes. Physiological and Biochemical Zoology 78(1): 18-30. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: An increase in temperature, within bounds, will accelerate development of reptile embryos, and morphogenesis can be normal over a range of temperatures despite those varying rates of development. Less well understood is the form of the relationship that best describes variation in developmental rate with temperature. In this article, we apply a linear degree.hour model, an empirical curvilinear model, a biophysical model, and a polynomial model to data on rates of embryonic development and temperature in the pig-nosed turtle Carettochelys insculpta from northern Australia. The curvilinear models, which have been applied with success to development of insects, describe the embryonic development of turtles well. When fluctuating temperatures extend beyond the constant temperatures that support successful incubation, the curvilinear models continue to perform well, whereas the linear model predictions fail. Sensitivity analysis indicates that under some circumstances, incubation duration may be increased by diel temperature fluctuations, independent of an influence of mean temperature. In other circumstances, incubation duration may be decreased, and in still other circumstances, diel temperature fluctuations will have no impact on incubation duration. This adds an additional dimension to our understanding of how thermal regimes can be selected or manipulated by reptiles to optimise incubation duration and the timing of offspring emergence.
Descriptors: pig nosed turtle, Carettochelys insculpta, embryo, physiology, models, temperature, development, morphogenesis, thermal regimes.

Glen, F., A.C.G.B.J. Broderick, and G.C. Hays (2003). Incubation environment affects phenotype of naturally incubated green turtle hatchlings. Journal of the Marine Biological Association of the United Kingdom 83(5): 1183-1186. ISSN: print: 0025-3154; online: 1469-7769.
Descriptors: reptiles, green turtle hatchlings, incubation environment, phenotype, affects, body size.

Godfrey, M.H. and N. Mrosovsky (2006). Pivotal temperature for green sea turtles, Chelonia mydas, nesting in Suriname. Herpetological Journal 16(1): 55-61. ISSN: 0268-0130.
Descriptors: reptiles, green sea turtles, Chelonia mydas, pivotal temperature, sexual differentiation, nesting, Surinam.

Herczeg, G., T. Kovacs, T. Toth, J. Torok, Z. Korsos, and J. Merila (2004). Tail loss and thermoregulation in the common lizard Zootoca vivipara. Die Naturwissenschaften 91(10): 485-488. ISSN: print: 0028-1042; online: 1432-1904.
Abstract: Tail autotomy in lizards is an adaptive strategy that has evolved to reduce the risk of predation. Since tail loss reduces body mass and moving ability-which in turn are expected to influence thermal balance-there is potential for a trade-off between tail autotomy and thermoregulation. To test this hypothesis, we studied a common lizard (Zootoca vivipara) population at high latitude, inhabiting a high-cost thermal environment. Z. vivipara is a small, non-territorial lizard known as a very accurate thermoregulator. We made two predictions: (1) the reduced body weight due to tail loss results in faster heating rate (a benefit), and (2) the reduction in locomotor ability after tail loss induces a shift to the use of thermally poorer microhabitats (a cost), thus decreasing the field body temperatures of active lizards. We did not find any effect of tail loss on heating rate in laboratory experiments conducted under different thermal conditions. Likewise, no significant relationship between tail condition and field body temperatures, or between tail condition and thermal microhabitat use, were detected. Thus, our results suggest that tail autotomy does not influence the accuracy of thermoregulation in small-bodied lizards.
Descriptors: common lizard, Zootoca vivipara, body temperature regulation, lizards physiology, tail, body size, body temperature, ecosystem, lizards anatomy and histology.

Herczeg, G., A. Gonda, J. Saarikivi, and J. Merila (2006). Experimental support for the cost-benefit model of lizard thermoregulation. Behavioral Ecology and Sociobiology 60(3): 405-414. ISSN: 0340-5443.
Descriptors: reptiles, thermoregulation, cost benefit, lizard model, experimental support, behavioral thermoregulation, body temperature.

Hochscheid, S., F. Bentivegna, and J.R. Speakman (2004). Long-term cold acclimation leads to high Q10 effects on oxygen consumption of loggerhead sea turtles Caretta caretta. Physiological and Biochemical Zoology 77(2): 209-222. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: We monitored oxygen consumption (VO2), body temperatures (Tb), submersion intervals, and circadian rhythms of VO2 in nine loggerhead turtles during a 6-mo period. The turtles originated from the Tyrhennian Sea, South Italy (40 degrees 51'N, 14 degrees 17'E) and were kept in indoor tanks at constant photoperiod while being subject to the seasonal decline in water temperature (Tw=27.1 degrees to 15.3 degrees C). From summer to winter, all turtles underwent profound reductions in VO2 (Q10=5.4). Simultaneously, their activity was greatly reduced and submergence intervals increased. Over 24-h periods, however, the turtles showed no circadian rhythm in activity or VO2. However, there was a significant positive correlation between the proportion of a day spent actively swimming and VO2. Tb's were not significantly different from Tw and followed the same seasonal decline. A second experiment was conducted to establish the effect of short-term exposure to various temperatures on VO2. Tb equilibrated with the experimental Tw within 3 h. The metabolic responses were again positively correlated with changes in Tw, but this time the corresponding Q10 was only 1.3. On the basis of the range of body masses of the turtles used in this study (2-60 kg), the intraspecific scaling exponent for VO2 was 0.353.
Descriptors: reptiles, loggerhead sea turtles, Caretta caretta, long term cold, oxygen consumption, effects, body temperature, acclimation, submersion intervals.

Hochscheid, S., F. Bentivegna, and J.R. Speakman (2002). Regional blood flow in sea turtles: implications for heat exchange in an aquatic ectotherm. Physiological and Biochemical Zoology 75(1): 66-76. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: Despite substantial knowledge on thermoregulation in reptiles, the mechanisms involved in heat exchange of sea turtles have not been investigated in detail. We studied blood flow in the front flippers of two green turtles, Chelonia mydas, and four loggerhead turtles, Caretta caretta, using Doppler ultrasound to assess the importance of regional blood flow in temperature regulation. Mean blood flow velocity and heart rate were determined for the water temperature at which the turtles were acclimated (19.3 degrees-22.5 degrees C) and for several experimental water temperatures (17 degrees-32 degrees C) to which the turtles were exposed for a short time. Flipper circulation increased with increasing water temperature, whereas during cooling, flipper circulation was greatly reduced. Heart rate was also positively correlated with water temperature; however, there were large variations between individual heart rate responses. Body temperatures, which were additionally determined for the two green turtles and six loggerhead turtles, increased faster during heating than during cooling. Heating rates were positively correlated with the difference between acclimation and experimental temperature and negatively correlated with body mass. Our data suggest that by varying circulation of the front flippers, turtles are capable of either transporting heat quickly into the body or retaining heat inside the body, depending on the prevailing thermal demands.
Descriptors: reptiles, sea turtles, Caretta caretta, regional blood flow, heat exchange, implications, flipper blood flow, body temperatures.

Ibarguengoytia, N.R. (2005). Field, selected body temperature and thermal tolerance of the syntopic lizards Phymaturus patagonicus and Liolaemus elongatus (Iguania: Liolaemidae). Journal of Arid Environments 62(3): 435-448. ISSN: 0140-1963.
NAL Call Number: QH541.5.D4J6
Descriptors: reptiles, lizards, Phymaturus patagonicus, Liolaemus elongatus, Iguanidae, air temperature, body temperature, heat tolerance, thermoregulation, animal reproduction, animal morphology, Argentina.

Klein, W., D.V. Andrade, T. Wang, and E.W. Taylor (2002). Effects of temperature and hypercapnia on ventilation and breathing pattern in the lizard Uromastyx aegyptius microlepis. Comparative Biochemistry and Physiology. Part A, Molecular and Integrative Physiology 132(4): 847-859. ISSN: 1095-6433.
Abstract: In most reptiles, the ventilatory response to hypercapnia consists of large increases in tidal volume (V(T)), whereas the effects on breathing frequency (f(R)) are more variable. The increased V(T) seems to arise from direct inhibition of pulmonary stretch receptors. Most reptiles also exhibit a transitory increase in ventilation upon removal of CO(2) and this post-hypercapnic hyperpnea may consist of changes in both V(T) and f(R). While it is well established that increased body temperature augments the ventilatory response to hypercapnia, the effects of temperature on the post-hypercapnic hyperpnea is less described. In the present study, we characterise the ventilatory response of the agamid lizard Uromastyx aegyptius to hypercapnia and upon the return to air at 25 and 35 degrees C. At both temperatures, hypercapnia caused large increases in V(T) and small reductions in f(R), that were most pronounced at the higher temperature. The post-hypercapnic hyperpnea, which mainly consisted of increased f(R), was numerically larger at 35 compared to 25 degrees C. However, when expressed as a proportion of the levels of ventilation reached during steady-state hypercapnia, the post-hypercapnic hyperpnea was largest at 25 degrees C. Some individuals exhibited buccal pumping where each expiratory thoracic breath was followed by numerous small forced inhalations caused by contractions of the buccal cavity. This breathing pattern was most pronounced during severe hypercapnia and particularly evident during the post-hypercapnic hyperpnea.
Descriptors: reptiles, lizard, Uromastyx aegyptius microlepis, temperature, hypercapnia, effects, ventilation, breathing, tidal volume, breathing frequency.

Krosniunas, E.H. and J.W. Hicks (2003). Cardiac output and shunt during voluntary activity at different temperatures in the turtle, Trachemys scripta. Physiological and Biochemical Zoology 76(5): 679-694. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: Red-eared slider turtles (Trachemys scripta) were chronically instrumented with blood flow probes for a long-term study of voluntary behavior in an enriched laboratory setting. Cardiovascular measures consisting of total cardiac output (Q(tot)), pulmonary blood flow (Q(pul)), systemic blood flow (Q(sys)), net cardiac shunt (Q(shunt)), heart rate (HR), and stroke volume (SV) were obtained during spontaneous activity at a constant body temperature (Tb=2 degrees C) and at unstable (variable) T(b)'s ranging from 19 degrees to 37 degrees C. The effects of temperature and activity differed between the pulmonary and systemic circuits, with increases in Q(sys) due to HR alone, while both HR and SV contributed to gains in Q(pul). At stable 20 degrees C, cardiovascular responses during diving, submerged swimming, and walking were qualitatively similar, and increases in Q(tot) during activity ( approximately 2 x resting levels) were due to greater gains in Q(pul) than Q(sys). At unstable T(b)'s and in general, net Q(shunt) while active depended on the integration of individual physiological influences such as heating, cooling, and initial behavioral state acting on the cardiovascular system. During activity, net left-to-right (L-R) shunts predominated at constant T(b) of 20 degrees C (mean shunt fraction approximately 30%-40%), while both net L-R and right-to-left (R-L) shunts of varying size were found at unstable T(b)'s (19 degrees - 37 degrees C).
Descriptors: reptiles, turtle, Trachemys scripta, cardiac output, shunt, voluntary activity, different temperatures, body temperature, heart rate.

Ladyman, M. and D. Bradshaw (2003). The influence of dehydration on the thermal preferences of the Western tiger snake, Notechis scutatus. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 173(3): 239-246. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: Temperature selection in tiger snakes (Notechis scutatus) is strongly influenced by hydration state and this response varies between two distinct neighbouring populations on semi-arid Carnac Island and mainland wetland (Herdsman Lake). Fed and hydrated (control) Carnac Island snakes selected a preferred body temperature of 26.2+/-1.2 degrees C and an average maximum temperature of 32.5+/-0.5 degrees C in a photo-thermal gradient. Dehydrated Carnac Island snakes selected a significantly lower preferred body temperature (19.7+/-1.6 degrees C) and average maximum temperature (27.7+/-1.0 degrees C). Control Herdsman Lake snakes selected a preferred body temperature of 27.5+/-0.6 degrees C and an average maximum temperature of 33.3+/-0.4 degrees C. Dehydrated Herdsman Lake snakes selected a significantly lower preferred body temperature (23.3+/-1.1 degrees C) and a lower average maximum temperature (31.8+/-0.6 degrees C). Thermal depression (decreased preferred body and average maximum temperatures) in response to dehydration was greater for Carnac Island than Herdsman Lake snakes. As decreases in temperature and activity can reduce water loss, our laboratory data suggest that the survival of the relict population of tiger snakes on Carnac Island is associated with thermoregulatory modifications, which may have the effect of enhancing water conservation in this waterless habitat.
Descriptors: reptiles, western tiger snake, Notechis scutatus, dehydration, influence, thermal preferences, hydration state, body temperature.

Lance, V.A. (2003). Alligator physiology and life history: the importance of temperature. Experimental Gerontology 38(7): 801-805. ISSN: 0531-5565.
Descriptors: reptiles, alligators, physiology, life history, temperature, annual thermal cycles, ambient temperature, anorexia below 16 degrees C, conference proceedings.
Notes: Meeting Information: Proceedings of the 2nd Symposium on Organisms with Slow Aging (SOSA-2), Los Angeles, USA, 17-18 January 2003.

Langkilde, T. and R. Shine (2005). Different optimal offspring sizes for sons versus daughters may favor the evolution of temperature-dependent sex determination in viviparous lizards. Evolution International Journal of Organic Evolution 59(10): 2275-2280. ISSN: print: 0014-3820; online: 1558-5646.
NAL Call Number: 443.8 Ev62
Abstract: Temperature-dependent sex determination (TSD) has evolved independently in at least two lineages of viviparous Australian scincid lizards, but its adaptive significance remains unclear. We studied a montane lizard species (Eulamprus heatwolei) with TSD. Our data suggest that mothers can modify the body sizes of their offspring by selecting specific thermal regimes during pregnancy (mothers with higher and more stable temperatures produced smaller offspring), but cannot influence sons versus daughters differentially in this way. A field mark-recapture study shows that optimal offspring size differs between the sexes: larger body size at birth enhanced the survival of sons but reduced the survival of daughters. Thus, a pregnant female can optimize the fitness of either her sons or her daughters (via yolk allocation and thermoregulation), but cannot simultaneously optimize both. One evolutionary solution to reduce this fitness cost is to modify the sex-determining mechanism so that a single litter consists entirely of either sons or daughters; TSD provides such a mechanism. Previous work has implicated a sex difference in optimal offspring size as a selective force for TSD in turtles. Hence, opposing fitness determinants of sons and daughters may have favored evolutionary transitions from genetic sex determination to TSD in both oviparous turtles and viviparous lizards.
Descriptors: viviparous lizards, sex determination, temperature dependent sex determination, TSD, offspring sizes, evolution.

Litvinov, N. and S. Ganshchuk (2005). Environment and body temperatures of reptiles in Volga-Ural region. Russian Journal of Herpetology 12(Suppl.): 179-182 . ISSN: 1026-2296.
Descriptors: reptiles, body temperature, environmental temperature, cardiovascular response, circulatory system, Eurasia, Volga Ural region.

Litzgus, J.D. and W.A. Hopkins (2003). Effect of temperature on metabolic rate of the mud turtle (Kinosternon subrubrum). Journal of Thermal Biology 28(8): 595-600. ISSN: 0306-4565.
NAL Call Number: QP82.2.T4J6
Descriptors: reptiles, mud turtle, Kinosternon subrubrum, temperature, metabolic rate, effect, oxygen consumption, ectotherms.

Liu, C., R. Li, Z. Liu, S. Yin, and Z. Wang (2006). The role of prostaglandins and the hypothalamus in thermoregulation in the lizard, Phrynocephalus przewalskii (Agamidae). Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 176(4): 321-328. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: Typically, small lizards rely heavily on behavioral thermoregulation rather than physiological mechanisms to control their rates of warming and cooling. We tested the hypothesis that prostaglandins participate in mediating the cardiovascular response to heating and cooling and temperature regulating neurons in the hypothalamus of the small lizard Phrynocephalus przewalskii. In vivo and in vitro treatments, heart rates (HRs) were all found to be higher during heating than during cooling, hysteresis was distinct below 30 and 26 degrees Celsius, respectively. In vivo, as administration of COX inhibitor, there were no differences in HR between heating and cooling at any body temperature and administration of agonist prostaglandins only produced a significant effect on HR below 25 degrees Celsius. Single-unit activity was recorded extracellularly in vitro with microelectrodes, found the firing rate of the continuous unit increased 23% when the temperature of the artificial cerebrospinal fluid dropped from 30-20 degrees Celsius. We conclude that prostaglandins appear to play only a limited role in modulating heart activity in Phrynocephalus przewalskii and suggest that cold-sensitive neurons in the preoptic and anterior hypothalamus (PO/AH) are involved in thermoregulatory control during heating or cooling.
Descriptors: lizards, Phrynocephalus przewalskii, body temperature regulation, heart rate, drug effects, hypothalamus, blood supply, prostaglandins, pharmacology, regional blood flow, sodium chloride pharmacology.

Llewelyn, J., R. Shine, and J.K. Webb (2006). Time of testing affects locomotor performance in nocturnal versus diurnal snakes. Journal of Thermal Biology 31(3): 268-273. ISSN: 0306-4565.
NAL Call Number: QP82.2.T4J6
Descriptors: reptiles, nocturnal snakes, diurnal snakes, locomotor performance, time of testing, affects, time of day.

Lu, H.L., X. Ji, L.H. Lin, and L. Zhang (2006). Relatively low upper threshold temperature in lizards from cool habitats. Journal of Thermal Biology 31(3): 256-261. ISSN: 0306-4565.
NAL Call Number: QP82.2.T4J6
Descriptors: reptiles, lizards, cool habitats, low upper threshold temperature, incubation temperature, forest skink.

Lutterschmidt, D.I., W.I. Lutterschmidt, N.B. Ford, and V.H. Hutchison (2002). Behavioral thermoregulation and the role of melatonin in a nocturnal snake. Hormones and Behavior 41(1): 41-50. ISSN: 0018-506X.
NAL Call Number: QP801.H7H64
Abstract: Daily and seasonal variations in hormone levels influence the complex interactions between behavior and physiology. Ectothermic animals possess the unique ability behaviorally to adjust body temperature (T(b)) to control physiological rate processes. Thus, a hormone may indirectly influence a physiological rate by directly influencing the behaviors that adjust or control that rate process. Although many hormonal influences on behavioral regulation of T(b) remain uninvestigated, melatonin (MEL) generally is considered a hormone that decreases mean preferred T(b). Many ectotherms demonstrate the selection of lower T(b)'s in response to increased MEL concentrations. Here, we examined the influence of MEL on the behavioral regulation of T(b) in the nocturnal African house snake Lamprophis fuliginosus. A series of experiments with two injection regimes of MEL had no significant effect on the mean preferred T(b) of L. fuliginosus. In addition, mean preferred T(b)'s during the photophase did not differ significantly from those during scotophase. Our findings suggest that L. fuliginosus does not respond to elevated concentrations of either endogenous or exogenous MEL. To verify that the African house snake is nocturnal, we investigated activity patterns of L. fuliginosus throughout the photoperiod. The activity period of L. fuliginosus occurs in the scotophase of the photoperiod, a pattern consistent with that of nocturnal species. This suggests that nocturnal organisms such as L. fuliginosus may not respond to MEL in the same manner as many diurnal species. Our results support the hypothesis that some animals, particularly nocturnal species, may have developed alternative responses to increased plasma concentrations of MEL.
Descriptors: reptiles, nocturnal snake, Lamprophis fuliginosus, behavioral thermoregulation, role of melatonin, body temperature.

McConnachie, S. and G.J. Alexander (2004). The effect of temperature on digestive and assimilation efficiency, gut passage time and appetite in an ambush foraging lizard, Cordylus melanotus melanotus. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 174(2): 99-105. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: In ectotherms, an increase in body temperature increases metabolic rate and may increase rates of digestive processes. We measured the thermal dependence of the apparent digestive and apparent assimilation efficiencies (ADE and AAE), gut passage time (GP) and appetite in Cordylus melanotus melanotus, a medium sized Crag Lizard, which is endemic to South Africa. Trials were conducted at 20, 22, 25, 30, 32 and 35 degrees C under controlled conditions. Trials lasted 14 days, during which, lizards were fed ca. 1 g mealworms per day. Glass beads were used as markers to determine GP at the beginning and end of trials. Faeces and urates were collected daily and oven dried at 50 degrees C. The energy content of egested matter was then measured using bomb calorimetry. ADE and AAE were not affected by temperature for either males or females. The mean+/-SE ADE and AAE were 94.4+/-0.3% and 87.2+/-0.6%, respectively. GP was not significantly different between males and females at any temperature, but decreased significantly with increasing temperature. Appetite was significantly different between the different temperatures measured. The decrease of gut passage time with increasing temperature was expected, since the digestive and assimilation efficiencies are similar over the range of temperatures tested. Lizards are thus assimilating a similar proportion of ingested energy, but at faster rates at higher temperatures. The results indicate that the digestive physiology of this species results in maximum energy gain per meal in environments where food is scarce.
Descriptors: reptiles, Crag lizard, Cordylus melanotus melanotus, digestive efficiency, assimilation efficiency, gut passage time, appetite, effect of temperature.

Mcconnachie, S., G.J. Alexander, and M.J. Whiting (2007). Lower temperature tolerance in the temperate, ambush foraging lizard Pseudocordylus melanotus melanotus. Journal of Thermal Biology 32(2): 66-71. ISSN: 0306-4565.
NAL Call Number: QP82.2.T4J6
Descriptors: reptiles, lizard, Pseudocordylus melanotus melanotus, temperature tolerance, lower, critical minimum, thermal limit, lower lethal temperature, thermal tolerance.

Meek, R. (2005). Null models and the thermal biology of the anguid lizard Anguis fragilis; evidence for thermoregulation? Amphibia Reptilia 26(4): 445-450. ISSN: 0173-5373.
Descriptors: reptiles, anguid lizard, Anguis fragilis, thermal biology, thermoregulation, null models, body temperature.

O'Donnell, R.P. and S.J. Arnold (2005). Evidence for selection on thermoregulation: effects of temperature on embryo mortality in the garter snake Thamnophis elegans. Copeia 2005(4): 930-934. ISSN: 0045-8511.
Descriptors: reptiles, garter snake, Thamnophis elegans, thermoregulation, effects of temperature, embryo mortality.

Overgaard, J., T. Wang, O.B. Nielsen, and H. Gesser (2005). Extracellular determinants of cardiac contractility in the cold anoxic turtle. Physiological and Biochemical Zoology 78(6): 976-995. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: Painted turtles (Chrysemys picta) survive months of anoxic submergence, which is associated with large changes in the extracellular milieu where pH falls by 1, while extracellular K+, Ca++, and adrenaline levels all increase massively. While the effect of each of these changes in the extracellular environment on the heart has been previously characterized in isolation, little is known about their interactions and combined effects. Here we examine the isolated and combined effects of hyperkalemia, acidosis, hypercalcemia, high adrenergic stimulation, and anoxia on twitch force during isometric contractions in isolated ventricular strip preparations from turtles. Experiments were performed on turtles that had been previously acclimated to warm (25 degrees C), cold (5 degrees C), or cold anoxia (submerged in anoxic water at 5 degrees C). The differences between acclimation groups suggest that cold acclimation, but not anoxic acclimation per se, results in a downregulation of processes in the excitation-contraction coupling. Hyperkalemia (10 mmol L(-1) K+) exerted a strong negative inotropic effect and caused irregular contractions; the effect was most pronounced at low temperature (57%-97% reductions in twitch force). Anoxia reduced twitch force at both temperatures (14%-38%), while acidosis reduced force only at 5 degrees C (15%-50%). Adrenergic stimulation (10 micromol L(-1)) increased twitch force by 5%-19%, but increasing extracellular [Ca++] from 2 to 6 mmol L(-1) had only small effects. When all treatments were combined with anoxia, twitch force was higher at 5 degrees C than at 25 degrees C, whereas in normoxia twitch force was higher at 25 degrees C. We propose that hyperkalemia may account for a large part of the depressed cardiac contractility during long-term anoxic submergence.
Descriptors: painted turtles, Chrysemys picta, anoxic, cold, cardiac contractility, extracellular determinants, long term anoxic submergence.

Packard, G.C. and M.J. Packard (2006). The relationship between gut contents and supercooling capacity in hatchling painted turtles (Chrysemys picta). Comparative Biochemistry and Physiology. Part A, Molecular and Integrative Physiology 144(1): 98-104. ISSN: 1095-6433.
Abstract: Painted turtles (Chrysemys picta) typically spend their first winter of life in a shallow, subterranean hibernaculum (the natal nest) where they seemingly withstand exposure to ice and cold by resisting freezing and becoming supercooled. However, turtles ingest soil and fragments of eggshell as they are hatching from their eggs, and the ingestate usually contains efficient nucleating agents that cause water to freeze at high subzero temperatures. Consequently, neonatal painted turtles have only a modest ability to undergo supercooling in the period immediately after hatching. We studied the limit for supercooling (SCP) in hatchlings that were acclimating to different thermal regimes and then related SCPs of the turtles to the amount of particulate matter in their gastrointestinal (GI) tract. Turtles that were transferred directly from 26 degrees C (the incubation temperature) to 2 degrees C did not purge soil from their gut, and SCPs for these animals remained near -4 degrees C for the 60 days of the study. Animals that were held at 26 degrees C for the duration of the experiment usually cleared soil from their GI tract within 24 days, but SCPs for these turtles were only slightly lower after 60 days than they were at the outset of the experiment. Hatchlings that were acclimating slowly to 2 degrees C cleared soil from their gut within 24 days and realized a modest reduction in their SCP. However, the limit of supercooling in the slowly acclimating animals continued to decline even after all particulate material had been removed from their GI tract, thereby indicating that factors intrinsic to the nucleating agents themselves also may have been involved in the acclimation of hatchlings to low temperature. The lowest SCPs for turtles that were acclimating slowly to 2 degrees C were similar to SCPs recorded in an earlier study of animals taken from natural nests in late autumn, so the current findings affirm the importance of seasonally declining temperatures in preparing animals in the field to withstand conditions that they will encounter during winter.
Descriptors: turtles, Chrysemys picta, acclimatization physiology, body temperature regulation, digestive system metabolism, hibernation physiology, turtles physiology, cold, species specificity.

Packard, G.C. and M.J. Packard (2003). Natural freeze-tolerance in hatchling painted turtles? Comparative Biochemistry and Physiology. Part A, Molecular and Integrative Physiology 134(2): 233-246. ISSN: 1095-6433.
Abstract: Hatchlings of the North American painted turtle (Family Emydidae: Chrysemys picta) typically spend their first winter of life inside a shallow, subterranean hibernaculum (the natal nest) where life-threatening conditions of ice and cold commonly occur. Although a popular opinion holds that neonates exploit a tolerance for freezing to survive the rigors of winter, hatchlings are more likely to withstand exposure to ice and cold by avoiding freezing altogether-and to do so without the benefit of an antifreeze. In the interval between hatching by turtles in late summer and the onset of wintery weather in November or December, the integument of the animals becomes highly resistant to the penetration of ice into body compartments from surrounding soil, and the turtles also purge their bodies of catalysts for the formation of ice. These two adjustments, taken together, enable the animals to supercool to temperatures below those that they routinely experience in nature. However, cardiac function in hatchlings is diminished at subzero temperatures, thereby compromising the delivery of oxygen to peripheral tissues and eliciting an increase in reliance by those tissues on anaerobic metabolism for the provision of ATP. The resulting increase in production of lactic acid may disrupt acid/base balance and lead to death even in animals that remain unfrozen. Although an ability to undergo supercooling may be key to survival by overwintering turtles in northerly populations, a similar capacity to resist inoculation and undergo supercooling characterizes animals from a population near the southern limit of distribution, where winters are relatively benign. Thus, the suite of characters enabling hatchlings to withstand exposure to ice and cold may have been acquired prior to the northward dispersal of the species at the end of the Pleistocene, and the characters may not have originated as adaptations specifically to the challenges of winter.
Descriptors: reptiles, hatchling painted turtles, Chrysemys picta, natural freeze tolerance, ice, cold, cardiac function, oxygen delivery, North America.

Packard, G.C. and M.J. Packard (2003). Effect of cold-acclimation on capacity for supercooling in hatchling painted turtles. SICB Annual Meeting and Exhibition Final Program and Abstracts 2003: 267-268. ISSN: print: 1540-7063; online: 1557-7023.
Descriptors: reptiles, painted turtles, Chrysemys picta, supercooling, cold acclimation, effect, capacity, meeting abstracts.
Notes: Meeting Information: Annual Meeting and Exhibition of the SICB (Society for Integrative and Comparative Biology), Toronto, ON, Canada; January 04-08, 2003.

Packard, G.C. and M.J. Packard (2004). Natural freeze-tolerance in reptiles. CryoLetters 25(3): 235-236. ISSN: 0143-2044.
Descriptors: reptiles, natural freeze tolerance, temperature, hibernation.

Packard, M.J. and G.C. Packard (2003). Cold acclimation and cutaneous resistance to freezing in hatchling painted turtles, Chrysemys picta. SICB Annual Meeting and Exhibition Final Program and Abstracts 2003: 268. ISSN: print: 1540-7063; online: 1557-7023.
Descriptors: reptiles, cold acclimation, freezing, hatchling painted turtles, Chrysemys picta, cutaneous resistance, meeting abstrascts.
Notes: Meeting Information: Annual Meeting and Exhibition of the SICB (Society for Integrative and Comparative Biology), Toronto, ON, Canada; January 04-08, 2003.

Pafilis, P., J. Foufopoulos, N. Poulakakis, P. Lymberakis, and E. Valakos (2007). Digestive performance in five Mediterranean lizard species: effects of temperature and insularity. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 177(1): 49-60. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: Temperature sensitivity of digestive processes has important ramifications for digestive performance in ectothermic vertebrates. We conducted a comparative analysis of temperature effects on digestive processes [gut passage times (GPTs) and apparent digestive efficiencies (ADEs)] in five lacertid lizards occurring in insular (Podarcis erhardii, P. gaigeae), and mainland (P. muralis, P. peloponnesiaca, Lacerta graeca) Mediterranean environments. GPTs were negatively correlated to temperature with mainland taxa having 10-20% longer GPTs than island taxa. In contrast to previous studies that estimate ADEs using bomb calorimetry, we compare ADEs by analyzing discrete efficiencies for lipids, sugars and proteins at three temperature regimes (20, 25, and 30 degrees C); each of these categories produces different results. ADEs for lipids and sugars showed a monotonic increase with temperature whereas ADEs for proteins decreased with temperature. Island taxa had consistently higher ADEs than their mainland counterparts for lipids and for proteins but not for sugars. They are characterized by superior energy acquisition abilities despite significantly shorter GPTs. Their increased digestive performance relative to the mainland species appears to allow them to maximize energy acquisition in unproductive island environments where food availability is spatially and seasonally clustered.
Descriptors: reptiles, Mediterranean lacertid lizards, digestive performance, effects of temperature, insularity, gut passage time, apparent digestive efficiencies.

Petersen, A.M., T.T. Gleeson, and D.A. Scholnick (2003). The effect of oxygen and adenosine on lizard thermoregulation. Physiological and Biochemical Zoology 76(3): 339-347. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: A regulated decrease in internal body temperature (Tb) appears to play a protective role against metabolic disruptions such as exposure to ambient hypoxia. This study examined the possibility that Tb depression is initiated when low internal oxygen levels trigger the release of adenosine, a neural modulator known to influence thermoregulation. We measured selected Tb of Anolis sagrei in a thermal gradient under varied ambient oxygen conditions and following the administration of the adenosine receptor antagonist 8-cyclopentyltheophylline (CPT). The average decrease in Tb observed following exposure to hypoxia (<10% O2) and following exhaustive exercise were 5 degrees and 3 degrees C, respectively, suggesting a role of oxygen availability on initiation of regulated hypothermia. When A. sagrei were run to exhaustion and recovered in hyperoxic (>95% O2) conditions, exercise-induced Tb depression was abolished. Administration of CPT similarly abolished decreased Tb due to both exercise and hypoxia. Trials using Dipsosaurus dorsalis indicate that elevated ambient oxygen during exercise does not influence blood pH or lactate accumulation, suggesting that these factors do not initiate changes in thermoregulatory setpoint following exhaustive exercise. We suggest that when oxygen is limiting, a decrease in arterial oxygen may trigger the release of adenosine, thereby altering the thermoregulatory setpoint.
Descriptors: reptiles, lizard, thermoregulation, oxygen, adenosine, effect, body temperature, ambient hypoxia, blood pH.

Pieau, C. and M. Dorizzi (2004). Oestrogens and temperature-dependent sex determination in reptiles: All is in the gonads. Journal of Endocrinology 181(3): 367-377. ISSN: 0022-0795.
Online: http://dx.doi.org/10.1677/joe.0.1810367
NAL Call Number: 448.8 J8293
Abstract: In many species of oviparous reptiles, the first steps of gonadal sex differentiation depend on the incubation temperature of the eggs. Feminization of gonads by exogenous oestrogens at a male-producing temperature and masculinization of gonads by antioestrogens and aromatase inhibitors at a female-producing temperature have irrefutably demonstrated the involvement of oestrogens in ovarian differentiation. Nevertheless, several studies performed on the entire gonad/adrenal/mesonephros complex failed to find differences between male- and female-producing temperatures in oestrogen content, aromatase activity and aromatase gene expression during the thermosensitive period for sex determination. Thus, the key role of aromatase and oestrogens in the first steps of ovarian differentiation has been questioned, and extragonadal organs or tissues, such as adrenal, mesonephros, brain or yolk, were considered as possible targets of temperature and sources of the oestrogens acting on gonadal sex differentiation.In disagreement with this view, experiments and assays carried out on the gonads alone, i.e. separated from the adrenal/mesonephros, provide evidence that the gonads themselves respond to temperature shifts by modifying their sexual differentiation and are the site of aromatase activity and oestrogen synthesis during the thermosensitive period. Oestrogens act locally on both the cortical and the medullary part of the gonad to direct ovarian differentiation. We have concluded that there is no objective reason to search for the implication of other organs in the phenomenon of temperature-dependent sex determination in reptiles. From the comparison with data obtained in other vertebrates, we propose two main directions for future research: to examine how transcription of the aromatase gene is regulated and to identify molecular and cellular targets of oestrogens in gonads during sex differentiation, in species with strict genotypic sex determination and species with temperature-dependent sex determination.
Descriptors: reptiles, sex determination, gonads, estrogens, temperture dependent, incubation temperature.

Plummer, M.V., T.L. Crabill, N.E. Mills, and S.L. Allen (2005). Body temperatures of free-ranging softshell turtles (Apalone spinifera) in a small stream. Herpetological Review 36(4): 371-375. ISSN: 0018-084X.
NAL Call Number: QL640.H47
Descriptors: reptiles, softshell turtles, Apalone spinifera, body temperature, free ranging, small stream, thermoregulation.

Plummer, M.V., B.K. Williams, M.M. Skiver, and J.C. Carlyle (2003). Effects of dehydration on the critical thermal maximum of the desert box turtle (Terrapene ornata luteola). Journal of Herpetology 37(4): 747-750. ISSN: 0022-1511.
NAL Call Number: QL640.J6
Descriptors: reptiles, desert box turtle, Terrapene ornata luteola, dehydration, effects, critical thermal maximum.

Quinn, A.E., A. Georges, S.D. Sarre, F. Guarino, T. Ezaz, and J.A. Graves (2007). Temperature sex reversal implies sex gene dosage in a reptile. Science 316(5823): 411. ISSN: 0036-8075.
Abstract: Sex in reptiles is determined by genes on sex chromosomes or by incubation temperature. Previously these two modes were thought to be distinct, yet we show that high incubation temperatures reverse genotypic males (ZZ) to phenotypic females in a lizard with ZZ and ZW sex chromosomes. Thus, the W chromosome is not necessary for female differentiation. Sex determination is probably via a dosage-sensitive male-determining gene on the Z chromosome that is inactivated by extreme temperatures. Our data invite a novel hypothesis for the evolution of temperature-dependent sex determination (TSD) and suggest that sex chromosomes may exist in many TSD reptiles.
Descriptors: reptiles, temperature, sex reversal, sex gene, dosage, sex chromosomes, incubation, temperature dependent sex deterimation.

Radmilovich, M., A. Fernandez, and O. Trujillo Cenoz (2003). Environment temperature affects cell proliferation in the spinal cord and brain of juvenile turtles. Journal of Experimental Biology. 206(Pt 17): 3085-3093. ISSN: 0022-0949.
Online: http://dx.doi.org/10.1242/jeb.00515
NAL Call Number: 442.8 B77
Abstract: The spinal cords and brains--comprising dorsal cortex (DC), medial cortex (MC) and diencephalon (Dien)--of juvenile turtles acclimated to warm temperature [27-30 degrees C; warm-acclimated turtles (WATs)] revealed higher density values of bromodeoxyuridine-labeled cells (BrdU-LCs) than those acclimated to a cooler environment [5-14 degrees C; cold-acclimated turtles (CATs)]. Both populations were under the influence of the seasonal daily light-dark rhythms. Pronounced differences between WATs and CATs (independent t-test; confidence level, P<0.01) were found in the central area of the spinal gray matter and in the ependymal epithelium lining the brain ventricles. Forebrain regions (DC, MC and Dien) also revealed significant differences between WATs and CATs (independent t-test; confidence level, P<0.01-0.05). Unexplored biological clocks that may be affecting cell proliferation were equalized by performing paired experiments involving one WAT and one CAT. Both animals were injected on the same day at the same time and both were sacrificed 24 h later. These experiments confirmed that a warm environment increased cell proliferation in the CNS of turtles. Double- and triple-labeling experiments involving anti-BrdU antibody together with anti-glial protein antibodies revealed that temperature modulates not only cell populations expressing glial markers but also other cells that do not express them. As expected, in the case of short post-injection (BrdU) surviving time points, no cells were found colabeling for BrdU and NeuN (neuronal marker). The probable direct effect of temperature on the cell division rate should be analyzed together with potential indirect effects involving increased motor activity and increased food intake. The fate of the increased BrdU-LCs (death, permanence as progenitor cells or differentiation following neuronal or glial lines) remains a matter for further investigation. Results are discussed in the light of current opinions concerned with post-natal neurogenesis in vertebrates.
Descriptors: reptiles, juvenile turtles, environmental temperature, affects, cell proliferation, spinal cord, brain.

Ray, P.P. and B.R. Maiti (2003). Interrenal responses to high ambient temperature in soft-shelled turtle, Lissemys punctata punctata. Indian Journal of Experimental Biology 41(8): 880-884. ISSN: 0019-5189.
NAL Call Number: 442.8 IN2
Abstract: An exposure to ambient temperature of 25 degrees C had no perceptible effect on interrenal function but further increase of temperature to 35 degrees C caused nuclear hypertrophy with increase of nuclear diameter, RNA concentration, acid phosphatase and alkaline phosphatase activities, accompanied by quantitative depletions of cholesterol (free, esterified and total) and ascorbic acid levels in the interrenal gland of the soft-shelled turtle Lissemys p. punctata. Similar manifestations of stimulation, except in the nucleus, were marked after exposure to 38 degrees C, but the degree of response in respect of esterified and free cholesterol levels was higher at 38 degrees C than at 35 degrees C. Moreover, withdrawal of 38 degrees C temperature and subsequently maintaining at 25 degrees C for 15 days showed reverse manifestations to those of 35 degrees C/38 degrees C, leading to a tendency towards normalcy. It is suggested that high a ambient temperature of 35 degrees C significantly stimulates interrenal function of Lissemys turtles, but further increase of 38 degrees C does not cause further overall stimulation, and withdrawal of higher temperature (38 degrees C) shows a tendency towards normalcy. It is also suggested that (a) high ambient temperature causes thermal stress, (b) it is reversible and (c) it acts on interrenal activity presumably via CRF-ACTH-axis in turtles.
Descriptors: reptiles, soft-shelled turtle, Lissemys p. punctata, high ambient temperature, internal response, thermal stress.

Ray, P.P. and B.R. Maiti (2003). Interrenal responses to high ambient temperature in soft-shelled turtle, Lissemys punctata punctata. Indian Journal of Experimental Biology 41(8): 880-884. ISSN: 0019-5189.
NAL Call Number: 442.8 IN2
Descriptors: reptiles, soft shelled turtle, Lissemys punctata punctata, high ambient temperature, interrenal responses.

Rhen, T. and J.W. Lang (2004). Phenotypic effects of incubation temperature in reptiles. In: N. Valenzuela and V. Lance (Editors), Temperature Dependent Sex Determination in Vertebrates, Smithsonian Books: Washington, DC, p. 90-98. ISBN: 1588342034.
NAL Call Number: QP278.5 .T45 2004
Descriptors: reptiles, sex determination, temperature dependent.

Robert, K.A., M.B. Thompson, and F. Seebacher (2006). Thermal biology of a viviparous lizard with temperature-dependant sex determination. Journal of Thermal Biology 31(4): 292-301. ISSN: 0306-4565.
NAL Call Number: QP82.2.T4J6
Descriptors: reptiles, viviparous lizard, thermal biology, sex determination, temperature dependant.

Row, J.R. and G. Blouin Demers (2006). Thermal quality influences effectiveness of thermoregulation, habitat use, and behaviour in milk snakes. Oecologia 148(1): 1-11. ISSN: print: 0029-8549; online: 1432-1939.
NAL Call Number: QL750.O3
Abstract: We investigated the link between thermal quality and the effectiveness of thermoregulation in milk snakes in a thermally challenging environment. We defined thermoregulatory effectiveness as the extent to which an individual maintains its body temperature (Tb) closer to the preferred range (Tset) than allowed by the thermal quality of its environment. We defined thermal quality as the magnitude of the difference between operative environmental temperatures (Te) and Tset. Because ectotherms regulate body temperatures through choice of habitat and behavioural adjustments, we also examined the link between thermoregulation, habitat use and behaviour. During 2003-2004, we located 25 individuals 890 times, and recorded their Tb. Thermal quality was lower in the spring and fall than in the summer, and was lower in forests than in open habitats. Milk snakes thermoregulated more effectively in the spring than in the summer and fall, and more effectively in the forest than in open habitats. Milk snakes had a strong preference for open habitats in all seasons, which was likely to facilitate behavioural thermoregulation. The preference for open habitats was equally strong in all seasons and, therefore, the higher effectiveness of thermoregulation was not a result of altered habitat use. Instead, milk snakes modified their behaviour and were seen basking more and moved less in the spring than in the summer.
Descriptors: reptiles, milk snakes, thermal quality, thermoregulation, habitat use, behavior, effectiveness, body temperature, ectotherms.

Sears, M.W. (2005). Geographic variation in the life history of the sagebrush lizard: the role of thermal constraints on activity. Oecologia 143(1): 25-36. ISSN: print: 0029-8549; online: 1432-1939.
NAL Call Number: QL750.O3
Abstract: Thermal constraints on the time available for activity have been proposed as a proximate mechanism to explain variation in suites of life history traits. The longer that an ectotherm can maintain activity, the more time it has to forage and the greater chance that it will encounter a predator and be eaten. Thus, the thermal environment may produce a trade off between growth and survival when variation in the environment favors increased activity. I used mark-recapture data from a demographic study of three natural populations of the sagebrush lizard (Sceloporus graciosus) and estimates of thermal opportunity for each population to evaluate whether variation in the thermal environment can explain patterns of growth and survival that occur over an elevational gradient. Lizards from the highest elevation population exhibited higher individual growth rates than those of lizards from lower elevation, while mortality rates increased with elevation for these populations. The covariation of fast growth and high mortality with increased thermal opportunity is the opposite trend expected if the thermal environment alone is to explain patterns of life history in these lizards. Additional factors including thermal heterogeneity in the distribution of microhabitats of lizards, adaptation to local environmental conditions, and a potential trade-off between resource acquisition and predation risk need to be addressed to obtain a satisfactory explanation of the causative mechanisms producing life history variation.
Descriptors: lizards, thermal constraints, activity, ectotherm, thermal environment, patterns of growth, survival, predation risk.

Seebacher, F. (2005). A review of thermoregulation and physiological performance in reptiles: what is the role of phenotypic flexibility? Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 175(7): 453-461. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: Biological functions are dependent on the temperature of the organism. Animals may respond to fluctuation in the thermal environment by regulating their body temperature and by modifying physiological and biochemical rates. Phenotypic flexibility (reversible phenotypic plasticity, acclimation, or acclimatisation in rate functions occurs in all major taxonomic groups and may be considered as an ancestral condition. Within the Reptilia, representatives from all major groups show phenotypic flexibility in response to long-term or chronic changes in the thermal environment. Acclimation or acclimatisation in reptiles are most commonly assessed by measuring whole animal responses such as oxygen consumption, but whole animal responses are comprised of variation in individual traits such as enzyme activities, hormone expression, and cardiovascular functions. The challenge now lies in connecting the changes in the components to the functioning of the whole animal and its fitness. Experimental designs in research on reptilian thermal physiology should incorporate the capacity for reversible phenotypic plasticity as a null-hypothesis, because the significance of differential body temperature-performance relationships (thermal reaction norms) between individuals, populations, or species cannot be assessed without testing that null-hypothesis.
Descriptors: reptiles, body temperature regulation, physiology, fluctuations, thermal environment, acclimatization, oxygen consumption, review.

Seebacher, F., R.M. Elsey, and P.L.3. Trosclair (2003). Body temperature null distributions in reptiles with nonzero heat capacity: seasonal thermoregulation in the American alligator (Alligator mississippiensis). Physiological and Biochemical Zoology 76(3): 348-359. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: Regulation of body temperature may increase fitness of animals by ensuring that biochemical and physiological processes proceed at an optimal rate. The validity of current methods of testing whether or not thermoregulation in reptiles occurs is often limited to very small species that have near zero heat capacity. The aim of this study was to develop a method that allows estimation of body temperature null distributions of large reptiles and to investigate seasonal thermoregulation in the American alligator (Alligator mississippiensis). Continuous body temperature records of wild alligators were obtained from implanted dataloggers in winter (n=7, mass range: 1.6-53.6 kg) and summer (n=7, mass range: 1.9-54.5 kg). Body temperature null distributions were calculated by randomising behavioural postures, thereby randomly altering relative animal surface areas exposed to different avenues of heat transfer. Core body temperatures were predicted by calculations of transient heat transfer by conduction and blood flow. Alligator body temperatures follow regular oscillations during the day. Occasionally, body temperature steadied during the day to fall within a relatively narrow range. Rather than indicating shuttling thermoregulation, however, this pattern could be predicted from random movements. Average daily body temperature increases with body mass in winter but not in summer. Daily amplitudes of body temperature decrease with increasing body mass in summer but not in winter. These patterns result from differential exposure to heat transfer mechanisms at different seasons. In summer, alligators are significantly cooler than predictions for a randomly moving animal, and the reverse is the case in winter. Theoretical predictions show, however, that alligators can be warmer in winter if they maximised their sun exposure. We concluded that alligators may not rely exclusively on regulation of body temperature but that they may also acclimatise biochemically to seasonally changing environmental conditions.
Descriptors: reptiles, American alligator, body temperature, seasonal thermoregulation, nonzero heat capacity, Alligator mississippiensis.

Seebacher, F. and C.E. Franklin (2005). Physiological mechanisms of thermoregulation in reptiles: a review. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 175(8): 533-541. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: The thermal dependence of biochemical reaction rates means that many animals regulate their body temperature so that fluctuations in body temperature are small compared to environmental temperature fluctuations. Thermoregulation is a complex process that involves sensing of the environment, and subsequent processing of the environmental information. We suggest that the physiological mechanisms that facilitate thermoregulation transcend phylogenetic boundaries. Reptiles are primarily used as model organisms for ecological and evolutionary research and, unlike in mammals, the physiological basis of many aspects in thermoregulation remains obscure. Here, we review recent research on regulation of body temperature, thermoreception, body temperature set-points, and cardiovascular control of heating and cooling in reptiles. The aim of this review is to place physiological thermoregulation of reptiles in a wider phylogenetic context. Future research on reptilian thermoregulation should focus on the pathways that connect peripheral sensing to central processing which will ultimately lead to the thermoregulatory response.
Descriptors: reptiles, thermoregulation, mechanisms, body temperature, biochemical reaction rates, physiology, review.

Seebacher, F. and C.E. Franklin (2004). Integration of autonomic and local mechanisms in regulating cardiovascular responses to heating and cooling in a reptile (Crocodylus porosus). Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 174(7): 577-585. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: Reptiles change heart rate and blood flow patterns in response to heating and cooling, thereby decreasing the behavioural cost of thermoregulation. We tested the hypothesis that locally produced vasoactive substances, nitric oxide and prostaglandins, mediate the cardiovascular response of reptiles to heat. Heart rate and blood pressure were measured in eight crocodiles (Crocodylus porosus) during heating and cooling and while sequentially inhibiting nitric-oxide synthase and cyclooxygenase enzymes. Heart rate and blood pressure were significantly higher during heating than during cooling in all treatments. Power spectral density of heart rate and blood pressure increased significantly during heating and cooling compared to the preceding period of thermal equilibrium. Spectral density of heart rate in the high frequency band (0.19-0.70 Hz) was significantly greater during cooling in the saline treatment compared to when nitric-oxide synthase and cyclooxygenase enzymes were inhibited. Cross spectral analysis showed that changes in blood pressure preceded heart rate changes at low frequencies (< 0.1 Hz) only. We conclude that the autonomic nervous system controls heart rate independently from blood pressure at higher frequencies while blood pressure changes determine heart rate at lower frequencies. Nitric oxide and prostaglandins do not control the characteristic heart rate hysteresis response to heat in C. porosus, although nitric oxide was important in buffering blood pressure against changes in heart rate during cooling, and inhibition caused a compensatory decrease in parasympathetic stimulation of the heart.
Descriptors: reptiles, crocodile, Crocodylus porosus, heating, cooling, cardiovascular responses, heart rate, blood flow, thermoregulation, blood pressure.

Seebacher, F. and C.E. Franklin (2003). Prostaglandins are important in thermoregulation of a reptile (Pogona vitticeps). Proceedings of the Royal Society of London. Series B, Biological Sciences 270(Suppl 1): S50-S53. ISSN: print: 0962-8452; online: 1471-2945.
Abstract: The effectiveness of behavioural thermoregulation in reptiles is amplified by cardiovascular responses, particularly by differential rates of heart beat in response to heating and cooling (heart-rate hysteresis). Heart-rate hysteresis is ecologically important in most lineages of ectothermic reptile, and we demonstrate that heart-rate hysteresis in the lizard Pogona vitticeps is mediated by prostaglandins. In a control treatment (administration of saline), heart rates during heating were significantly faster than during cooling at any given body temperature. When cyclooxygenase 1 and 2 enzymes were inhibited, heart rates during heating were not significantly different from those during cooling. Administration of agonists showed that thromboxane B(2) did not have a significant effect on heart rate, but prostacyclin and prostaglandin F(2alpha) caused a significant increase (3.5 and 13.6 beats min(-1), respectively) in heart rate compared with control treatments. We speculate that heart-rate hysteresis evolved as a thermoregulatory mechanism that may ultimately be controlled by neurally induced stimulation of nitric oxide production, or maybe via photolytically induced production of vitamin D.
Descriptors: reptiles, Pogona vitticeps, thermoregulation, prostaglandins, cardiovascular responses, heart beat, heating, cooling.

Seebacher, F. and R. Shine (2004). Evaluating thermoregulation in reptiles: the fallacy of the inappropriately applied method. Physiological and Biochemical Zoology 77(4): 688-695. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: Given the importance of heat in most biological processes, studies on thermoregulation have played a major role in understanding the ecology of ectothermic vertebrates. It is, however, difficult to assess whether body temperature is actually regulated, and several techniques have been developed that allow an objective assessment of thermoregulation. Almost all recent studies on reptiles follow a single methodology that, when used correctly, facilitates comparisons between species, climates, and so on. However, the use of operative temperatures in this methodology assumes zero heat capacity of the study animals and is, therefore, appropriate for small animals only. Operative temperatures represent potentially available body temperatures accurately for small animals but can substantially overestimate the ranges of body temperature available to larger animals whose slower rates of heating and cooling mean that they cannot reach equilibrium if they encounter operative temperatures that change rapidly through either space or time. This error may lead to serious misinterpretations of field data. We derive correction factors specific for body mass and rate of movement that can be used to estimate body temperature null distributions of larger reptiles, thereby overcoming this methodological problem.
Descriptors: reptiles, thermoregulation, evaluating, studies, body temperature, heating, cooling, small animals, large animals, applied method.

Seebacher, F., J. Sparrow, and M.B. Thompson (2004). Turtles (Chelodina longicollis) regulate muscle metabolic enzyme activity in response to seasonal variation in body temperature. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 174(3): 205-210. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Descriptors: reptiles, turtles, Chelodina longicollis, muscle metabolic enzyme activity, regulate, body temperature, seasonal variation.

Shanbhag, B.A., S.K. Saidapur, and R.S. Radder (2003). Lowering body temperature induces embryonic diapause during prolonged egg retention in the lizard, Calotes versicolor. Die Naturwissenschaften 90(1): 33-35. ISSN: print: 0028-1042; online: 1432-1904.
Abstract: The lizard Calotes versicolor delays oviposition of oviductal eggs for as long as 6 months or more under unfavourable conditions. During this period of prolonged egg retention, the growth of oviductal embryos is arrested at stage 34. The present study shows for the first time among reptiles that the "embryonic diapause" is manifested by the gravid females by lowering their body temperature ( T(b)) by 3-5 degrees C during the period of egg retention by mechanism(s) presently unknown.
Descriptors: reptiles, lizard, Calotes versicolor, prolonged egg retention, body temperature, lowering, embryonic diapause.

Shen, J.M., R.D. Li, and F.Y. Gao (2005). Effects of ambient temperature on lipid and fatty acid composition in the oviparous lizards, Phrynocephalus przewalskii. Comparative Biochemistry and Physiology. Part B, Biochemistry and Molecular Biology 142(3): 293-301. ISSN: 1096-4959.
Abstract: This study was designed to assess the effect of ambient temperature on lipid content, lipid classes and fatty acid compositions of heart, liver, muscle and brain in oviparous lizards, Phrynocephalus przewalskii, caught in the desert area of China. Significant differences could be observed in the contents of the total lipid and fatty acid compositions among different temperatures (4, 25 and 38 degrees C). The study showed that liver and muscle were principal sites of lipid storage. Triacylglycerol (TAG) mainly deposited in the liver, while phospholipids (PL) was identified as the predominant lipid class in the muscle and brain. Palmitic and stearic acid generally occupied the higher proportion in saturated fatty acids (SFA), while monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) consisted mainly of 16:1n-7, 18:1n-9, 18:2n-6, 18:3n-3, 20:4n-6 and 22:6n-3 regardless of tissue and temperature. These predominant fatty acids proportion fluctuations caused by temperature affected directly the ratio of unsaturated to saturated fatty acids. There was a tendency to increase the degree of unsaturation in the fatty acids of TAG and PL as environmental temperature dropped from 38 to 4 degrees C, although the different extent in different tissues. These results suggested that lipid characteristics of P. przewalskii tissues examined were influenced by ambient temperature.
Descriptors: lizards, Phrynocephalus przewalskii, ambient temperature, effects, lipid content, fatty acid, composition, heart, liver muscle, brain.

Southwood, A.L., R.D. Andrews, F.V. Paladino, and D.R. Jones (2005). Effects of diving and swimming behavior on body temperatures of pacific leatherback turtles in tropical seas. Physiological and Biochemical Zoology 78(2): 285-297. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: Mathematical models and recordings of cloacal temperature suggest that leatherback turtles (Dermochelys coriacea) maintain core body temperature higher than ambient water temperature (T(W)) while freely swimming at sea. We investigated the thermoregulatory capabilities of free-ranging leatherbacks and, specifically, the effect that changes in diving patterns and ambient temperatures have on leatherback body temperatures (T(B)). Data loggers were used to record subcarapace and gastrointestinal tract temperatures (T(SC) and T(GT), respectively), T(W), swim speed, dive depth, and dive times of female leatherback turtles during internesting intervals off the coast of Guanacaste, Costa Rica. Mean T(SC) (28.7 degrees -29.0 degrees C) was significantly higher than mean T(W) (25.0 degrees -27.5 degrees C). There was a significant positive relationship between T(SC) and T(W) and a significant negative correlation between T(SC) and dive depth and T(GT) and dive depth. Rapid fluctuations in T(GT) occurred during the first several days of the internesting interval, which suggests that turtles were ingesting prey or water during this time. Turtles spent 79%-91% of the time at sea swimming at speeds greater than 0.2 m s(-1), and the average swim speed was 0.7 +/- 0.2 m s(-1). Results from this study show that alterations in diving behavior and T(W) affect T(B) of leatherback turtles in the tropics. Body temperatures of free-ranging leatherback turtles correspond well with values for T(B) predicted by mathematical models for tropical conditions.
Descriptors: leatherback turtle, Dermochelys coriacea, diving, swimming, behavior, body temperature, effects, thermoregulatory capabilities, mathematical models.

Southwood, A.L., C.A. Darveau, and D.R. Jones (2003). Metabolic and cardiovascular adjustments of juvenile green turtles to seasonal changes in temperature and photoperiod. Journal of Experimental Biology 206(24): 4521-4531. ISSN: 0022-0949.
Online: http://dx.doi.org/10.1242/jeb.00689
NAL Call Number: 442.8 B77
Descriptors: repetiles, juvenile green turtles, temperature changes, photoperiod, metabolic, cardiovascular, adjustments.

Souza, F.L. and F.I. Martins (2006). Body temperature of free-living freshwater turtles, Hydromedusa maximiliani (Testudines, Chelidae). Amphibia Reptilia 27(3): 464-468. ISSN: 0173-5373.
Descriptors: reptiles, freshwater turtles, Hydromedusa maximiliani, free living, body temperature, water temperature, body size, Brazil.

Stawski, C.Y., G.C. Grigg, D.T. Booth, and L.A. Beard (2006). Temperature and the respiratory properties of whole blood in two reptiles, Pogona barbata and Emydura signata. Comparative Biochemistry and Physiology. Part A, Molecular and Integrative Physiology 143(2): 173-183. ISSN: 1095-6433.
Abstract: We investigated the capacity of two reptiles, an agamid lizard Pogona barbata and a chelid turtle Emydura signata, to compensate for the effects of temperature by making changes in their whole blood respiratory properties. This was accomplished by measuring the P50 (at 10, 20 and 30 degrees C), hematocrit (Hct), haemoglobin concentration ([Hb]) and mean cell haemoglobin concentration (MCHC) in field acclimatised and laboratory acclimated individuals. The acute effect of temperature on P50 in P. barbata, expressed as heat of oxygenation (deltaH), ranged from -16.8+/-1.84 to -28.5+/-2.73 kJ/mole. P50 of field acclimatised P. barbata increased significantly from early spring to summer at the test temperatures of 20 degrees C (43.1+/-1.2 to 48.8+/-2.1 mmHg) and 30 degrees C (54.7+/-1.2 to 65.2+/-2.3 mmHg), but showed no acclimation under laboratory conditions. For E. signata, deltaH ranged from -31.1+/-6.32 to -48.2+/-3.59 kJ/mole. Field acclimatisation and laboratory acclimation of P50 did not occur. However, in E. signata, there was a significant increase in [Hb] and MCHC from early spring to summer in turtles collected from the wild (1.0+/-0.1 to 1.7+/-0.2 mmol/L and 4.0+/-0.3 to 6.7+/-0.7 mmol/L, respectively).
Descriptors: reptiles, turtle, Emydura signata, lizard, Pogona barbata, temperature, respiratory properties, whole blood, acclimation.

Stinner, J.N. and J.H. Spencer (2003). Temperature and acid-base status in box turtles. FASEB Journal 17(4-5): Abstract No. 87.1. ISSN: 0892-6638.
NAL Call Number: QH301.F3
Descriptors: reptiles, box turtles, tempersture, acid base status, meeting abstracts.
Notes: Meeting Information: FASEB Meeting on Experimental Biology: Translating the Genome, San Diego, CA, USA; April 11-15, 2003.

Storey, K.B. (2006). Reptile freeze tolerance: metabolism and gene expression. Cryobiology 52(1): 1-16. ISSN: 0011-2240.
Abstract: Terrestrially hibernating reptiles that live in seasonally cold climates need effective strategies of cold hardiness to survive the winter. Use of thermally buffered hibernacula is very important but when exposure to temperatures below 0 degrees C cannot be avoided, either freeze avoidance (supercooling) or freeze tolerance strategies can be employed, sometimes by the same species depending on environmental conditions. Several reptile species display ecologically relevant freeze tolerance, surviving for extended times with 50% or more of their total body water frozen. The use of colligative cryoprotectants by reptiles is poorly developed but metabolic and enzymatic adaptations providing anoxia tolerance and antioxidant defense are important aids to freezing survival. New studies using DNA array screening are examining the role of freeze-responsive gene expression. Three categories of freeze responsive genes have been identified from recent screenings of liver and heart from freeze-exposed (5h post-nucleation at -2.5 degrees C) hatchling painted turtles, Chrysemys picta marginata. These genes encode (a) proteins involved in iron binding, (b) enzymes of antioxidant defense, and (c) serine protease inhibitors. The same genes were up-regulated by anoxia exposure (4 h of N2 gas exposure at 5 degrees C) of the hatchlings which suggests that these defenses for freeze tolerance are aimed at counteracting the injurious effects of the ischemia imposed by plasma freezing.
Descriptors: reptiles, painted turtles, Chrysemys picta marginata, body temperature, regulation physiology, cold, gene expression, physiology, antioxidants physiology, freezing, hibernation.

Sun, P., X. Xu, H. Chen, and X. Ji (2002). [Thermal tolerance, diel variation of body temperature, and thermal dependence of locomotor performance of hatchling soft-shelled turtles, Trionyx sinensis]. Ying Yong Sheng Tai Xue Bao. [Journal of Applied Ecology] 13(9): 1161-1165. ISSN: 0021-8901.
Abstract: The thermal tolerance, body temperature, and influence of temperature on locomotor performance of hatchling soft-shelled turtles (Trionyx sinensis) were studied under dry and wet conditions, and the selected body temperature of hatchlings was 28.0 and 30.3 degrees C, respectively. Under wet condition, the critical thermal maximum and minimum averaged 40.9 and 7.8 degrees C, respectively. In the environments without thermal gradients, the diel variation of body temperature was highly consistent with the variation of both air and water temperatures, and the body temperature was more directly affected by water temperature than by air temperature, which implied that the physiological thermoregulation of hatchling T. sinensis was very weak. In the environments with thermal gradients, hatchling turtles could maintain relatively high and constant body temperatures, primarily through behavioral thermoregulation. The locomotor performance of hatchling turtles was highly dependent on their body temperature. Within a certain range, the locomotor performance increased with increasing body temperature. In our study, the optimal body temperature for locomotor performance was 31.5 degrees C, under which, the maximum continuous running distance, running distance per minute, and number of stops per minute averaged 1.87 m, 4.92 m.min-1, and 6.2 times.min-1, respectively. The correspondent values at 33.0 degrees C averaged 1.30 m, 4.28 m.min-1, and 7.7 times.min-1, respectively, which indicated that the locomotor performance of hatchling turtles was impaired at 33.0 degrees C. Therefore, extremely high body temperatures might have an adverse effect on locomotor performance of hatchling turtles.
Descriptors: reptiles, shelled turtles, Trionyx sinensis, body temperature physiology, motor activity physiology, turtles physiology, body temperature regulation, cold, heat, water.
Language of Text: Chinese.

Talent, L.G. (2005). Effect of temperature on toxicity of a natural pyrethrin pesticide to green anole lizards (Anolis carolinensis). Environmental Toxicology and Chemistry 24(12): 3113-3116. ISSN: 0730-7268.
NAL Call Number: QH545.A1E58
Abstract: Metabolic rates of reptiles vary with body temperature; therefore, the sensitivity of reptiles to a particular dose level of a pesticide might be expected to vary as well. The purpose of the present study was twofold: To evaluate the effects of temperature on the toxicity to green anole lizards (Anolis carolinensis) of a single concentration of a natural pyrethrin pesticide via percutaneous exposure, and to compare the effects of temperature (20 vs 35 degrees C) on the toxicity of different concentrations of pyrethrins to green anoles. When lizards were exposed to a solution that contained 300 mg/L of pyrethrins, the mortality of lizards maintained at 15 and 20 degrees C was significantly higher (p < 0.01) than the mortality of lizards maintained at 35 and 38 degrees C. In addition, the median lethal concentrations of pyrethrins for lizards maintained at 20 and 35 degrees C were 77.6 and greater than 300 mg/L, respectively. Therefore, temperature clearly influenced the sensitivity of lizards to pyrethrin pesticides.
Descriptors: lizards, Anolis carolinensis, pesticides toxicity, pyrethrins toxicity, temperature, effect, pesticide, metabolic rates, reptiles, sensitivity.

Tanaka, K. (2005). Thermal aspects of melanistic and striped morphs of the snake Elaphe quadrivirgata. Zoological Science 22(11): 1173-1179. ISSN: 0289-0003.
NAL Call Number: QL1.Z68
Abstract: Temperature is a critical factor limiting various aspects of the biology of ectotherms. In addition to environmental factors, coloration and body size are two physical properties that influence ectotherms' body temperature (T(b)). I compared the influences of these properties on thermal aspects of the two morphs of the color-dimorphic snake (E. quadrivirgata) under experimental conditions. First, I fitted T(b) data during heating to the von Bertalanffy equation, but considered parameter values of the equilibrium temperature obtained to be biologically meaningless. Alternatively, I limited the data for comparison of the morphs to T(b) < or =35 degrees C, which was the T(b) at which snakes began to move vigorously in the experiment. The rate of T(b) increase was significantly greater in the melanistic morph than in the striped morph. Heating rate was negatively correlated with body size in both morphs. The interaction of body size and heating rate did not significantly differ between the two morphs. The possibility of linkage, due to thermal advantage, between small body size and the prevalence of melanism in the population studied is briefly discussed. Rapid increase of T(b) is biologically advantageous because snakes with such ability would be released from various time and environmental constraints associated with thermoregulation under particular environmental conditions.
Descriptors: snake, Elaphe quadrivirgata, body size, body temperature physiology, melanistic, morphs, striped, pigmentation physiology, time factors, Japan.

Tattersall, G.J., V. Cadena, and M.C. Skinner (2006). Respiratory cooling and thermoregulatory coupling in reptiles. Respiratory Physiology and Neurobiology 154(1-2): 302-318. ISSN: 1569-9048.
NAL Call Number: QP121.A1 R4
Descriptors: reptiles, respiratory cooling, thermoregulatory coupling, breathing, body temperature, head-body temperature differences.

Toledo, L.F., A.S. Abe, and D.V. Andrade (2003). Temperature and meal size effects on the postprandial metabolism and energetics in a boid snake. Physiological and Biochemical Zoology 76(2): 240-246. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: We investigated the combined effect of meal size and temperature on the aerobic metabolism and energetics of digestion in Boa constrictor amarali. Oxygen uptake rates (Vd2;o2) and the duration of the digestion were determined in snakes fed with meals equaling to 5%, 10%, 20%, and 40% of the snake's body mass at 25 degrees and 30 degrees C. The maximum Vd2;o2 values attained during digestion were greater at 30 degrees C than at 25 degrees C. Both maximal Vd2;o2 values and the duration of the specific dynamic action (SDA) were attained sooner at 30 degrees C than at 25 degrees C. Therefore, the temperature effect on digestion in Boa is characterized by the shortening of the SDA duration at the expense of increased Vd2;o2. Energy allocated to SDA was not affected by meal size but was greater at 25 degrees C compared to 30 degrees C. This indicates that a postprandial thermophilic response can be advantageous not only by decreasing the duration of digestion but also by improving digestive efficiency. Maximal Vd2;o2 and SDA duration increased with meal size at both temperatures.
Descriptors: reptiles, boid snake, Boa constrictor amarali, temperature, meal size, effects, postprandial metabolism, energetics.

Vallone, D., E. Frigato, C. Vernesi, A. Foa, N.S. Foulkes, and C. Bertolucci (2007). Hypothermia modulates circadian clock gene expression in lizard peripheral tissues. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 292(1): R160-R166. ISSN: print: 0363-6119; online: 1422-1490.
Online: http://dx.doi.org/10.1152/ajpregu.00370.2006
Abstract: The molecular mechanisms whereby the circadian clock responds to temperature changes are poorly understood. The ruin lizard Podarcis sicula has historically proven to be a valuable vertebrate model for exploring the influence of temperature on circadian physiology. It is an ectotherm that naturally experiences an impressive range of temperatures during the course of the year. However, no tools have been available to dissect the molecular basis of the clock in this organism. Here, we report the cloning of three lizard clock gene homologs (Period2, Cryptochrome1, and Clock) that have a close phylogenetic relationship with avian clock genes. These genes are expressed in many tissues and show a rhythmic expression profile at 29 degrees C in light-dark and constant darkness lighting conditions, with phases comparable to their mammalian and avian counterparts. Interestingly, we show that at low temperatures (6 degrees C), cycling clock gene expression is attenuated in peripheral clocks with a characteristic increase in basal expression levels. We speculate that this represents a conserved vertebrate clock gene response to low temperatures. Furthermore, these results bring new insight into the issue of whether circadian clock function is compatible with hypothermia.
Descriptors: reptiles, lizard, Podarcis sicula, circadian clock, hypothermia, modulates, gene expression, peripheral tissues, temperature changes.

Vladimirova, I.G., T.A. Alekseeva, and M.V. Nechaeva (2005). [Effect of temperature on the rate of oxygen consumption during the second half of embryonic and early postembryonic development of European pond turtle Emys orbicularis (Reptilia: Emydidae)]. Izvestiia Akademii Nauk. Seriia Biologicheskaia Rossiiskaia Akademiia Nauk(5): 585-591. ISSN: 1026-3470.
Abstract: Oxygen consumption by eggs of European pond turtle was determined at two constant incubation temperatures of 25 and 28 degrees C during the second half of embryogenesis. During development at both temperatures, the rate of oxygen consumption initially increased to remain constant during the last quarter of embryogenesis. The difference between the rates of oxygen consumption at these temperatures decreased during the studied period. The coefficient Q10 for the rate of oxygen consumption decreased from 9 to 1.7. At an incubation temperature of 28 degrees C, the changes in the rate of oxygen consumption in response to a short-term temperature decrease to 25 degrees C or increase to 30 degrees C depended on the developmental stage and were most pronounced at the beginning of the studied period. During late embryonic and first 2.5 months of postembryonic development, the rate of oxygen consumption did not significantly differ after such temperature changes. The regulatory mechanisms formed during embryonic development are proposed to maintain the level of oxygen consumption during temperature changes.
Descriptors: pond turtle, Emys orbicularis, temperature, turtles embryology, growth, development, oxygen consumption, eggs, turtles metabolism.
Language of Text: Russian.

Voituron, Y., S. Servais, C. Romestaing, T. Douki, and H. Barre (2006). Oxidative DNA damage and antioxidant defenses in the European common lizard (Lacerta vivipara) in supercooled and frozen states. Cryobiology 52(1): 74-82. ISSN: 0011-2240.
Abstract: The European common lizard (Lacerta vivipara) tolerates long periods at sub-zero temperatures, either in the supercooled or the frozen state. Both physiological conditions limit oxygen availability to tissues, compelling lizards to cope with potential oxidative stress during the transition from ischemic/anoxic conditions to reperfusion with aerated blood during recovery. To determine whether antioxidant defenses are implicated in the survival of lizards when facing sub-zero temperatures, we monitored the activities of antioxidant enzymes and oxidative stress either during supercooling or during freezing exposures (20 h at -2.5 degrees C) and 24 h after thawing in two organs of lizards--muscle and liver. Supercooling induced a significant increase in the total SOD and GPx activity in muscle (by 67 and 157%, respectively), but freezing had almost no effect on enzyme activity, either in muscle or in liver. By contrast, thawed lizards exhibited higher GPx activity in both organs (a 133% increase in muscle and 59% increase in liver) and a significant decrease in liver catalase activity (a 47% difference between control and thawed lizards). These data show that supercooling (but not freezing) triggers activation of the antioxidant system and this may be in anticipation of the overgeneration of oxyradicals when the temperature increases (while thawing or at the end of supercooling). Oxidative stress was assessed from the content of 8-oxodGuo and the different DNA adducts resulting from lipid peroxidation, but it was unaltered whatever the physiological state of the lizards, thus demonstrating the efficiency of the antioxidant system that has been developed by this species. Overall, antioxidant defenses appear to be part of the adaptive machinery for reptilian tolerance to sub-zero temperatures.
Descriptors: lizard, Lacerta vivipara, antioxidants, pharmacology, DNA damage, drug effects, lizards metabolism, oxidative stress, adaptation, metabolism, freezing, lipid peroxidation, liver metabolism, muscles metabolism, oxidative stress physiology.

Voituron, Y., J.M. Storey, C. Grenot, and K.B. Storey (2002). Freezing survival, body ice content and blood composition of the freeze-tolerant European common lizard, Lacerta vivipara. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 172(1): 71-76. ISSN: print: 0174-1578; online: 1432-136X.
NAL Call Number: QP33.J681
Abstract: To investigate the freeze tolerance of the European common lizard, Lacerta vivipara, we froze 17 individuals to body temperatures as low as -4 degrees C under controlled laboratory conditions. The data show that this species tolerates the freezing of 50% of total body water and can survive freezing exposures of at least 24-h duration. Currently, this represents the best known development of freeze tolerance among squamate reptiles. Freezing stimulated a significant increase in blood glucose levels (16.15+/- 1.73 micromol x ml(-1) for controls versus 25.06 +/- 2.92 micromol x ml(-1) after thawing) but this increase had no significant effect on serum osmolality which was unchanged between control and freeze-exposed lizards (506.0 +/- 23.8 mosmol x l(-1) versus 501.0 +/- 25.3 mosmol x l(-1), respectively). Tests that assessed the possible presence of antifreeze proteins in lizard blood were negative. Recovery at 5 degrees C after freezing was assessed by measurements of the mean time for the return of breathing (5.9 +/- 0.5 h) and of the righting reflex (44.8 +/- 4.5 h). Because this species hibernates in wet substrates inoculative freezing may frequently occur in nature and the substantial freeze tolerance of this lizard should play a key role in its winter survival.
Descriptors: reptiles, European common lizard, Lacerta vivipara, freezing survival, body ice, blood composition, freeze tolerant, serum osmolality, breathing.

Voituron, Y., B. Verdier, and C. Grenot (2002). The respiratory metabolism of a lizard (Lacerta vivipara) in supercooled and frozen states. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 283(1): R181-R186. ISSN: print: 0363-6119; online: 1522-1490.
Online: http://dx.doi.org/10.1152/ajpregu.00378.2001
Abstract: We investigated the respiratory metabolism of the overwintering lizard Lacerta vivipara while in either supercooled or frozen states. With a variable pressure and volume microrespirometer and a chromatograph, we show that the oxygen consumption of the supercooled animals showed a nonlinear relationship with temperature and an aerobic metabolism demand between 0.5 and -1.5 degrees C. A significant increase in the respiratory quotient (RQ) values indicated an increasing contribution by the anaerobic pathways with decreasing temperature. In the frozen state, two phases are easily detectable and are probably linked to the ice formation within the body. During the first 5-6 h, the animals showed an oxygen consumption of 3.52 +/- 0.28 microl. g(-1). h(-1) and a RQ value of 0.52 +/- 0.09. In contrast, after ice equilibrium, oxygen consumption decreased sharply (0.55 +/- 0.09 microl. g(-1). h(-1)) and the RQ values increased (2.49 +/- 0.65). The present study confirms the fact that supercooled invertebrates and vertebrates respond differently to subzero temperatures, in terms of aerobic metabolism, and it shows that aerobic metabolism persists under freezing conditions.
Descriptors: reptiles, lizard, Lacerta vivipara, cold, freezing, lizards metabolism, respiratory system metabolism, anaerobiosis, oxygen consumption, pulmonary gas exchange.

Voituron, Y. (2005). La tolerance au froid chez les reptiles. [Cold tolerance in reptiles.]. Bulletin De La Societe Herpetologique De France 113-114: 53-68. ISSN: 0754-9962.
Descriptors: reptiles, cold tolerance, arctic regions, freezing, mechanisms.
Language of Text: French; Summary in English and French.

Wang Hua, Wang Zheng Huan, Wang Zhen Wei, Gong Jin Nan, and Wang Xiao Ming (2006). Study on behavioral thermoregulation of Chinese alligator under artificial feeding condition. Chinese Journal of Zoology 41(6): 60-66. ISSN: 0250-3263.
Descriptors: reptiles, Chinese alligator, behavioral thermoregulation, artificial feeding condition.
Language of Text: Chinese.

Wapstra, E., M. Olsson, R. Shine, A. Edwards, R. Swain, and J.M. Joss (2004). Maternal basking behaviour determines offspring sex in a viviparous reptile. Proceedings of the Royal Society of London. Series B, Biological Sciences 271(Suppl. 4): S230-S232. ISSN: 0080-4649.
Abstract: Two primary dichotomies within vertebrate life histories involve reproductive mode (oviparity versus viviparity) and sex determination (genotypic sex determination versus environmental sex determination). Although reptiles show multiple evolutionary transitions in both parameters, the co-occurrence of viviparity and environmental-dependent sex determination have heretofore been regarded as incompatible. Our studies on the viviparous lizard Niveoscincus ocellatus show that the extent of basking by a female influences the sex of her offspring. Critically, our data reveal this effect both in the field (via correlations between date of birth and litter sex ratio) and in a laboratory experiment (females with reduced basking opportunities produced more male offspring). Changes in thermoregulatory behaviour thus allow pregnant female lizards to modify the sex of their offspring.
Descriptors: reptiles, viviparous lizard, Niveoscincus ocellatus, maternal basking, offspring sex, sex determination, thermoregulatory behavior.

Warner, D.A. and R. Shine (2005). The adaptive significance of temperature-dependent sex determination: experimental tests with a short-lived lizard. Evolution International Journal of Organic Evolution 59(10): 2209-2221. ISSN: print: 0014-3820; online: 1558-5646 .
NAL Call Number: 443.8 Ev62
Abstract: Why is the sex of many reptiles determined by the temperatures that these animals experience during embryogenesis, rather than by their genes? The Charnov-Bull model suggests that temperature-dependent sex determination (TSD) can enhance maternal fitness relative to genotypic sex determination (GSD) if offspring traits affect fitness differently for sons versus daughters and nest temperatures either determine or predict those offspring traits. Although potential pathways for such effects have attracted much speculation, empirical tests largely have been precluded by logistical constraints (i.e., long life spans and late maturation of most TSD reptiles). We experimentally tested four differential fitness models within the Charnov-Bull framework, using a short-lived, early-maturing Australian lizard (Amphibolurus muricatus) with TSD. Eggs from wild-caught females were incubated at a range of thermal regimes, and the resultant hatchlings raised in large outdoor enclosures. We applied an aromatase inhibitor to half the eggs to override thermal effects on sex determination, thus decoupling sex and incubation temperature. Based on relationships between incubation temperatures, hatching dates, morphology, growth, and survival of hatchlings in their first season, we were able to reject three of the four differential fitness models. First, matching offspring sex to egg size was not plausible because the relationship between egg (offspring) size and fitness was similar in the two sexes. Second, sex differences in optimal incubation temperatures were not evident, because (1) although incubation temperature influenced offspring phenotypes and growth, it did so in similar ways in sons versus daughters, and (2) the relationship between phenotypic traits and fitness was similar in the two sexes, at least during preadult life. We were unable to reject a fourth model, in which TSD enhances offspring fitness by generating seasonal shifts in offspring sex ratio: that is, TSD allows overproduction of daughters (the sex likely to benefit most from early hatching) early in the nesting season. In keeping with this model, hatching early in the season massively enhanced body size at the beginning of the first winter, albeit with a significant decline in probability of survival. Thus, the timing of hatching is likely to influence reproductive success in this short-lived, early maturing species; and this effect may well differ between the sexes.
Descriptors: Australian lizard, Amphibolurus muricatus, physiological, embryology, sex ratio, temperature, embryo, physiology, embryonic development, growth, development, reproduction, sex determination, genetics.

Warren, D.E., S.A. Reese, and D.C. Jackson (2006). Tissue glycogen and extracellular buffering limit the survival of red-eared slider turtles during anoxic submergence at 3 degrees C. Physiological and Biochemical Zoology 79(4): 736-744. ISSN: 1522-2152.
NAL Call Number: QL1.P52
Abstract: The goal of this study was to identify the factors that limit the survival of the red-eared slider turtle Trachemys scripta during long-term anoxic submergence at 3 degrees C. We measured blood acid-base status and tissue lactate and glycogen contents after 13, 29, and 44 d of submergence from ventricle, liver, carapace (lactate only), and four skeletal muscles. We also measured plasma Ca(2+), Mg(2+), Na(+), K(+), Cl(-), inorganic phosphate (P(i)), lactate, and glucose. After 44 d, one of the six remaining turtles died, while the other turtles were in poor condition and suffered from a severe acidemia (blood pH = 7.09 from 7.77) caused by lactic acidosis (plasma lactate 91.5 mmol L(-1)). An initial respiratory acidosis attenuated after 28 d. Lactate rose to similar concentrations in ventricle and skeletal muscle (39.3-46.1 micromol g(-1)). Liver accumulated the least lactate (21.8 micromol g(-1)), and carapace accumulated the most lactate (68.9 micromol g(-1)). Plasma Ca(2+) and Mg(2+) increased significantly throughout submergence to levels comparable to painted turtles at a similar estimated lactate load. Glycogen depletion was extensive in all tissues tested: by 83% in liver, by 90% in ventricle, and by 62%-88% in muscle. We estimate that the shell buffered 69.1% of the total lactate load, which is comparable to painted turtles. Compared with painted turtles, predive tissue glycogen contents and plasma HCO(-)(3) concentrations were low. We believe these differences contribute to the poorer tolerance to long-term anoxic submergence in red-eared slider turtles compared with painted turtles.
Descriptors: reptiles, painted turtles, red-eared slider turtle, Trachemys scripta, anoxic submergence, 3 degrees centigrade, tissue glycogen, extracellular buffering, survival.

Willingham, E.J. (2005). The effects of atrazine and temperature on turtle hatchling size and sex ratios. Frontiers in Ecology and the Environment 3(6): 309-313. ISSN: 1540-9295.
NAL Call Number: QL540.F76
Descriptors: reptiles, atrazine, temperature, effects, turtle hatchling size, sex ratios, reproduction, tocixity.

Xia, T.S., K.H. Zhou, and J.L. Zhu (2006). Influence of hibernant temperature on reproduction of Chinese alligator. Sichuan Journal of Zoology 25(2): 398-399. ISSN: 1000-7083.
Descriptors: reptiles, Chinese alligator, hibernant temperatute, reproduction, influence.
Language of Text: Chinese; Summary in Chinese and English.

Xu, X.F. and X. Ji (2006). Ontogenetic shifts in thermal tolerance, selected body temperature and thermal dependence of food assimilation and locomotor performance in a lacertid lizard, Eremias brenchleyi. Comparative Biochemistry and Physiology. Part A, Molecular and Integrative Physiology 143(1): 118-124. ISSN: 1095-6433.
Abstract: We used Eremias brenchleyi as a model animal to examine differences in thermal tolerance, selected body temperature, and the thermal dependence of food assimilation and locomotor performance between juvenile and adult lizards. Adults selected higher body temperatures (33.5 vs. 31.7 degrees C) and were able to tolerate a wider range of body temperatures (3.4-43.6 vs. 5.1-40.8 degrees C) than juveniles. Within the body temperature range of 26-38 degrees C, adults overall ate more than juveniles, and food passage rate was faster in adults than juveniles. Apparent digestive coefficient (ADC) and assimilation efficiency (AE) varied among temperature treatments but no clear temperature associated patterns could be discerned for these two variables. At each test temperature ADC and AE were both higher in adults than in juveniles. Sprint speed increased with increase in body temperature at lower body temperatures, but decreased at higher body temperatures. At each test temperature adults ran faster than did juveniles, and the range of body temperatures where lizards maintained 90% of maximum speed differed between adults (27-34 degrees C) and juveniles (29-37 degrees C). Optimal temperatures and thermal sensitivities differed between food assimilation and sprint speed. Our results not only show strong patterns of ontogenetic variation in thermal tolerance, selected body temperature and thermal dependence of food assimilation and locomotor performance in E. brenchleyi, but also add support for the multiple optima hypothesis for the thermal dependence of behavioral and physiological variables in reptiles.
Descriptors: Eremias brenchleyi, lizards, physiology, adaptation, body temperature, temperature regulation, digestion, eating, gastrointestinal transit, motor activity, temperature.

Zaar, M., E. Larsen, and T. Wang (2004). Hysteresis of heart rate and heat exchange of fasting and postprandial savannah monitor lizards (Varanus exanthematicus). Comparative Biochemistry and Physiology. Part A, Molecular and Integrative Physiology 137(4): 675-682. ISSN: 1095-6433.
Abstract: Reptiles are ectothermic, but regulate body temperatures (T(b)) by behavioural and physiological means. Body temperature has profound effects on virtually all physiological functions. It is well known that heating occurs faster than cooling, which seems to correlate with changes in cutaneous perfusion. Increased cutaneous perfusion, and hence elevated cardiac output, during heating is reflected in an increased heart rate (f(H)), and f(H), at a given T(b), is normally higher during heating compared to cooling ('hysteresis of heart rate'). Digestion is associated with an increased metabolic rate. This is associated with an elevated f(H) and many species of reptiles also exhibited a behavioural selection of higher T(b) during digestion. Here, we examine whether digestion affects the rate of heating and cooling as well as the hysteresis of heart rate in savannah monitor lizards (Varanus exanthematicus). Fasting lizards were studied after 5 days of food deprivation while digesting lizards were studied approximately 24 h after ingesting dead mice that equalled 10% of their body mass. Heart rate was measured while T(b) increased from 28 to 38 degrees C under a heat lamp and while T(b) decreased during a subsequent cooling phase. The lizards exhibited hysteresis of heart rate, and heating occurred faster than cooling. Feeding led to an increased f(H) (approximately 20 min(-1) irrespective of T(b)), but did not affect the rate of temperature change during heating or cooling. Therefore, it is likely that the increased blood flows during digestion are distributed exclusively to visceral organs and that the thermal conductance remains unaffected by the elevated metabolic rate during digestion.
Descriptors: reptiles, savannah monitor lizards, Varanus exanthematicus, heart rate, heat exchange, fasting, post prandial, body temperature, digestion, cardiac output, heating, cooling.

Zhang, Y.P., Z.C. Pan, and X. Ji (2003). Thermal tolerance, body temperature, and thermal dependence of locomotor performance of hatchling red-eared slider turtles, Trachemys scripta elegans. Acta Ecologica Sinica 23(6): 1048-1056. ISSN: 1000-0933.
Descriptors: reptiles, red-eared slider turtles, Trachemys scripta elegans, temperature, thermal tolerance, body temperature, locomotor performance, thermal dependence, hatchling.
Language of Text: Chinese; Summary in Chinese and English.

Zheng, R.Q., W.G. Du, Y.P. Zhang, and Y.X. Bao (2006). Influence of incubation temperature on embryonic use of energy and mineral metabolism in the Chinese three-keeled pond turtle Chinemys reevesii. Acta Zoologica Sinica 52(1): 21-27. ISSN: 0001-7302.
Descriptors: reptiles, pond turtle, Chinemys reevesii, incubation temperature, embryonic use of energy, mineral metabolism, influence.
Language of Text: Chinese; Summary in Chinese and English.

Zhu, X.P., Y.L. Chen, C.Q. Wei, Y.H. Liu, and J.F. Giu (2006). Temperature effects on sex determination in yellow pond turtle (Mauremys mutica Cantor). Acta Ecologica Sinica 26(2): 620-625. ISSN: 1000-0933.
Descriptors: reptiles, yellow pond turtle, Mauremys mutica, temperature effects, sex determination.
Language of Text: Chinese; Summary in Chinese and English.