The phylogeography and population genetic structure of least cisco (Coregonus sardinella) in Alaska

Abstract

The least cisco (Coregonus sardinella) is a whitefish species broadly distributed across the Arctic regions of Russia, Alaska, and Canada, and little is known about the genetic relationships among groups within this species. We investigated the genetic relationships among least cisco on two landscape scales. On a broader landscape scale, we investigated the relationships among populations across the state of Alaska by comparing mitochondria) DNA (mtDNA) sequences. On a finer landscape scale, we investigated the relationships among least cisco populations in closely located lakes on the Arctic Coastal Plain by comparing microsatellite DNA haplotypes. Data from mtDNA suggest that least cisco are relatively diverse across Alaska, with 68 unique haplotypes found in 305 individuals and a large proportion of genetic variation is shared across Alaska, but this variation is not homogeneously distributed across all regions and for all haplotype groups. Interpretation of microsatellite data was limited. Overall, the data suggest that least cisco populations are currently isolated from one another. Isolation also occurred historically, accounting for divergence among major Glades. But general recontact events occurred as isolated populations migrated and colonized new habitats, accounting for the heterogeneity found across Alaska. Ultimately, Alaskan least cisco may have functioned as a metapopulation historically, but present populations are too isolated to be considered a metapopulation today.