Evolution in Dolly Varden Across Geographic Scales

Fishes of the genus Salvelinus (charr) are morphologically and ecologically diverse and provide rich material for evolutionary studies.  Because Salvelinus has colonized recently deglaciated habitat following the last ice age, they provide opportunities to investigate recent morphological and genetic divergence as well as dispersal and vicariance events across geographic scales.  We investigated evolution in Dolly Varden across several geographic scales through morphological variation and mitochondrial DNA sequence variation.  Here, we present a series of sequential studies from Kamchatka, Russia, and North America. First, we compare morphological variation among five sympatric life history forms inhabiting the land locked Kronotski Lake in Kamchatka, Russia.  We then use mitochondrial DNA sequence variation to infer the evolutionary history among the landlocked morphs and an anadromous population inhabiting the lower Kronotski River.  The Dolly Varden inhabiting Kronotski Lake are particularly interesting and may represent an example of ecological speciation in progress.  Next, we examine genetic diversity among twenty Dolly Varden populations across Kamchatka to identify population structure and infer colonization events through phylogeographic history.  Finally, we present evolution across a broad geographic scale by comparing genetic diversity in Dolly Varden populations inhabiting Eastern Pacific drainages (Kamchatka) to populations inhabiting Western Pacific drainages (North America) across similar latitudes.  This comparison enables us to ask questions on how Dolly Varden evolution has differed between two continents across similar latitudes.