Research Programs: Sensitive Aquatic Species Conservation

Local Adaptation and Genetic Load in Cutthroat Trout

The overall goal of this project is to determine how evolution has shaped the entire genome of a species, and how this affects the fitness of populations and individuals within populations. The genetic composition, and therefore, evolutionary fitness, of populations is shaped by mutation, drift, inbreeding, migration, and selection. Selection, for example, tends to increase the fitness of populations by removing genes that are either deleterious or not suited for the local environment and by increasing the frequency of beneficial alleles. Selection, however, has its limits. It can be overwhelmed by drift in small populations and can operate only if there is adequate genetic variation to work with. Inbreeding, on the other hand, has the opposite effect upon fitness as selection. It increases homozygosity of deleterious recessive alleles, and, therefore, tends to decrease the fitness of populations. Gene flow and mutation can either help or hurt populations depending on whether new alleles increase or decrease a population’s ability to persist over time. Understanding how these evolutionary processes interact in nature is one of evolutionary biology’s most fundamental goals, and remarkable progress has been made in the past few decades. The Bozeman Fish Technology Center’s (BFTC) role in this collaborative project will be to assess how well stocks (cold and warm) of westslope cutthroat trout (WCT) survive and grow in a range of water temperatures.  WCT eggs will be collected from wild populations and fertilized streamside before being transported to the BFTC. Eggs will be incubated in Heath trays arranged in vertical incubators. Eggs will be acclimated to the experimental temperature treatments upon arrival to the BFTC, and egg quality will be assessed by determining percent fertilization. Developmental rates will be monitored at formation of the blastopore furrow, closure of the neural tube, and hatch. Percent abnormality and survival will be determined.  Once yolk absorption has occurred (swim-up stage), larvae will be reared for 90 days to assess growth rates among stocks at each temperature. 

Collaborators:  Montana State University; USGS, Montana Cooperative Fishery Research Unit; Montana Fish, Wildlife, and Parks; National Science Foundation

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