USGS Columbia Environmental Research Center Project: Phylogeographic Patterns of Thermal Tolerance: Predicting Ozark Crayfish Population Response to Climate Change

Statement of Problem: There is a critical need for data regarding the distribution and population status of species of conservation concern. State and Federal management agencies require these data for decisions regarding the listing of threatened and endangered species and the designation and management of lands for the protection of listed species. Data are also required to identify factors critical to explaining the distribution and status of species of conservation concern. With climatic warming, species richness and distribution will be a function of naturally-selected thermal tolerance, with more tightly constrained species (such as Ozark endemics) at greater risk than those with broader latitudinal ranges. Freshwater crayfishes are ecologically important and diverse, with over 372 described species in the United States and Canada; however, they are highly endangered, with greater than 48% of those species requiring some level of conservation concern. The diversity and broad distribution of Ozark crayfish populations make them ideal models for species adaptation to climate change. We will utilize phylogeographic patterns to explore the divergence of populations living in distinct thermal environments, and we will develop a gene expression assay for a highly-conserved biomarker of temperature stress, the heat shock protein 70 (hsp70). We hypothesize that crayfish in habitats exposed to elevated temperature regimes will exhibit increased expression of heat shock protein 70 (hsp70). The coldwater crayfish (Orconectes eupunctus) is currently designated as imperiled globally and in Missouri; as a Species of Greatest Conservation Need by the Arkansas Game and Fish Commission; and as threatened by the American Fisheries Society Endangered Species Committee. The coldwater crayfish is one of the world┬┐s most geographically restricted crayfishes, and a non-indigenous species is spreading within the watershed where it is found. In addition, its limited distribution puts it at risk for climate-related changes such as drought, decreased spring flows, and warmer stream temperatures. Our partners have designed a companion study to comprehensively document the distribution and status, and describe how genetic variation is distributed within and among populations of the coldwater crayfish. Their study also will address how anthropogenic and natural factors influence the observed distribution and densities (and thus the conservation status) of coldwater crayfish populations at multiple spatial scales. This proposal will complment the study of coldwater crayfish distribution by developing a novel tool for measurement of thermal stress, one of the possible limiting factors for the conservation of coldwater crayfish. We will investigate the relations between physiological adaptation to thermal stress and phylogeographic patterns in the coldwater crayfish, which may serve as a sensitive indicator species for global climate change. Study results will be integrated to enable state agencies to make conservation management decisions based on factors which have been identified with the decline of this species.

Objectives: Evaluate the relative sensitivity of cold-water crayfish to climate change based on genetic analysis based on the heat-inducible hsp70 gene. This information will be used to design degenerate primers to conserved regions of hsp70 for sequencing of the hsp70 gene in the coldwater crayfish.
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