Setting Conservation Priorities in a Widespread Species: Phylogeographic and Physiological Variation in the Lake Chub, Couesius plumbeus (Pisces: Cyprinidae)

Abstract

Defining units of conservation below the species level is a widely accepted conservation priority, but is especially challenging for widespread taxa that have experienced diverse geographic histories and exist across heterogenous environments. The lake chub (Pisces: Couesius plumbeus) is a widespread freshwater fish in North America and occurs from the southcentral USA to northwestern Alaska and Canada. We used mtDNA sequence analysis to test for divergent lineages predicted to occur as a result of survival of lake chub in distinct glacial refugia. Lake chub consisted of two major mtDNA lineages separated by 3.8% sequence divergence which are probably late to pre-Pleistocene in origin. We combined these data with those consistent with thermal adaptation in fish living in thermal springs versus those living in a lake with wide seasonal temperature variation, and with data on distribution of lake chub in major watershed units. We assessed these data against objective criteria developed to identify conservation units under Canadian endangered species legislation. Our analysis identified twelve major units of conservation within C. plumbeus that could be assessed under Canada’s Species-at-Risk Act. Our study illustrates how different character traits manifested at very different spatial scales can be used to define conservation units within widely-distributed taxa

Identifying designatable units for intraspecific conservation prioritization: a hierarchical approach applied to the lake whitefish species complex (Coregonusspp.)

“…Bernatchez and Wilson ; Taylor et al. ). Criterion 2 refers only to genetic lineages, allowing for the possibility that a given population (e.g.…”

“…Taylor et al. ). Important variation that is not captured by existing taxonomy is likely to be a common component of DU identification.…”

“…An evaluation of discreteness and significance according to these guidelines still requires some interpretation to apply these concepts to a given taxon, and it may be desirable to employ clear and repeatable criteria to guide an objective interpretation of the guidelines (e.g. Taylor et al 2013).…”

“…Distinct populations may be associated with variation in ecology, local adaptation or phylogeographic history that have not been recognized by systematists in the form of taxonomic designations below the species level (e.g. Taylor et al 2013). Important variation that is not captured by existing taxonomy is likely to be a common component of DU identification.…”

“…Few attempts have been made to apply the DU concept in such challenging cases. For instance, Taylor et al (2013) studied diverse and broadly distributed populations of lake chub (Pisces: Couesius plumbeus). They identified twelve DUs based on phylogenetic lineages, local physiological adaptation to thermal springs and presence in different biogeographic regions (Taylor et al 2013).…”