Vulnerability to Climate Change in Amphibians and Reptiles
Gary S. Casper*, University of Wisconsin - Milwaukee Field Station, WI  

The amphibians and reptiles occupying the Upper Midwest have responded to periodic 
episodes of climate change, with range retractions, expansions, and evolutionary responses 
such as allopatric speciation. The most recent such event was the retreat of the Pleisticene 
ice sheets ca. 10,000 ybp. Prior to this retreat, glaciated regions of the Upper Midwest were 
essentially free of amphibians and reptiles, and the species present today are the result of 
recolonization of these glaciated regions from southerly refugia. Recolonization pathways 
are beginning to be reconstructed from molecular phylogeography studies. These results 
illustrate the importance of the location of refugia, changing climate, and barriers to 
movement such as the prairie peninsula and the glacial lakes, including in modern times the 
Great Lakes. For this study I examine a suite of Upper Midwest amphibians and reptiles 
from a climate change perspective. Most climate models suggest that Wisconsin will 
become warmer and drier. This analysis examines a number of species variables relevant 
to this predicted climate change, such as range limits, reproductive potential, ecological 
specializations, and mobility. Species are also examined for sensitivity to a number of 
variables related to a warmer and drier climate, such as reduced summer soil moisture, 
lower summer water tables, lower summer stream flows, increased temperatures, and 
reduced snow and ice cover. This analysis suggests both negative and positive responses, 
depending on whether conditions favor or disfavor a particular species ecological 
requirements, and how movements may be constrained where species must migrate with 
changing conditions in order to maintain occupation of favorable habitats.
*Presenter