Pleistocene glaciations and contemporary genetic diversity in a Beringian fish, the broad whitefish, Coregonus nasus (Pallas): inferences from microsatellite DNA variation

Abstract

The contemporary distribution of genetic variation within and among high latitude populations cannot be fully understood without taking into consideration how species responded to the impacts of Pleistocene glaciations. Broad whitefish, Coregonus nasus, a species endemic to northwest North America and the Arctic coast of Russia, was undoubtedly impacted by such events because its geographic distribution suggests that it survived solely within the Beringian refuge from where it dispersed post‐glacially to achieve its current range. We used microsatellite DNA to investigate the role of glaciations in promoting intraspecific genetic variation in broad whitefish (N = 14 localities, 664 fish) throughout their North American range and in one Russian sample. Broad whitefish exhibited relatively high intrapopulation variation (average of 11.7 alleles per locus, average HE = 0.61) and moderate levels of interpopulation divergence (overall FST = 0.10). The main regions assayed in our study (Russia, Alaska, Mackenzie River and Travaillant Lake systems) were genetically differentiated from each other and there were declines in genetic diversity with distance from putative refugia. Additionally, Mackenzie River system populations showed less developed and more variable patterns of isolation‐by‐distance than populations occupying former Alaskan portions of Beringia. Finally, our data suggest that broad whitefish dispersed from Beringia using coastal environments and opportunistically via headwater stream connections that once existed between Yukon and Mackenzie River drainages. Our results illustrate the importance of history (e.g. glaciation) and contemporary dispersal ecology in shaping the current genetic population structure of Arctic faunas.

Life-history characteristics and landscape attributes as drivers of genetic variation, gene flow, and fine-scale population structure in northern Dolly Varden (Salvelinus malma malma) in Canada

“…In theory (e.g., Bernatchez and Wilson 1998), and as demonstrated in numerous empirical examples (Shafer et al 2010;Sepulveda-Villet and Stepien 2012), genetic diversity should be highest in populations currently inhabiting regions not impacted by glacial events. Furthermore, decreases in genetic diversity should be associated with increasing distance from glacial refugia (e.g., Muller et al 2008;Harris and Taylor 2010). This pattern is consistent with bottlenecks and founder effects in populations that postglacially colonized novel habitats as they became ice-free and, as such, harbour only a subset of the genetic variability of the source, refugial population(s) (Hewitt 1996;Provan and Bennett 2008).…”

Geographic influences on fine-scale, hierarchical population structure in northern Canadian populations of anadromous Arctic Char (Salvelinus alpinus)

“…We resolved significant patterns of isolation-bydistance (IBD) when assessed using F ST as our genetic distance metric, but not when using D. Although significant patterns of IBD are common in anadromous populations of salmonids (e.g., Heath et al 2001;King et al 2001), there are numerous examples where this is not the case (e.g., Vaha et al 2007;Harris and Taylor 2010b). Non-significant patterns of IBD observed among northern populations of fishes can be explained by insufficient time since postglacial colonization for IBD patterns to evolve (Castric and Bernatchez 2003).…”

“…Numerous additional examples of moderate, but significant population subdivision among anadromous salmonids also exist (e.g., Nielsen et al 2009;Harris and Taylor 2010b;Palstra and Ruzzante 2010). Employing Bayesian clustering implemented in STRUCTURE, hierarchical genetic population structure was identified in Cumberland Sound Arctic char.…”

Post-glacial dispersal patterns of Northern pike inferred from an 8800 year old pike (Esox cf. lucius) skull from interior Alaska

“…The timing and mode of post-glacial dispersal of fish out of Beringia was mediated by glacial re-advances, pro-glacial lakes, outburst floods, and habitat succession after deglaciation (Bernatchez and Wilson, 1998). For example, shortly after deglaciation, Broad Whitefish colonized the Mackenzie River basin through the Arctic Ocean and via glacial meltwater connections with the Yukon River basin (Harris and Taylor, 2010). Many freshwater species dispersing from full glacial Beringia are now widespread in North America.…”

“…Beringia offers a globally important case study because much of it was unglaciated during the Pleistocene and served as the primary refugium for many freshwater species during glacial periods (Cumbaa et al, 1981;Bernatchez and Wilson, 1998;Cox and Hebert, 2001;Weider and Hobaek, 2003;Harris and Taylor, 2010). Salmonid fishes with facultative or obligatory marine stages as part of their life history dominate the freshwater fish fauna in Beringia (Oswood et al, 2000).…”