The Origin and Genetic Diversity of Kokanee (Oncorhynchus nerka) On the Katmai National Park and Preserve, Alaska

Kokanee, the non-anadromous and less common form of sockeye salmon, Oncorhynchus nerka, reside in lakes and in their native range generally occur near populations of sockeye salmon.  Studies examining the genetic relationship of kokanee and sockeye indicate that geographically proximate populations of the two forms are genetically distinct but are more closely related to each other than to populations of like forms that are geographically distant. These studies support the parallel evolution hypothesis whereby sockeye colonizing lake systems after the last glacial period gave rise to kokanee on multiple occasions.  In this study we further evaluate the parallel evolution hypothesis in kokanee and sockeye but on a fine geographic scale by examining the origin and genetic diversity in three geographically distinct kokanee populations on the Katmai National Park and Preserve in southwest Alaska.  First, we compare two neighboring but geographically isolated kokanee populations to assess if they were derived from the same or different sockeye populations and to estimate the time of divergence.  Next, we evaluate the origin of a kokanee population in a large sockeye salmon lake system to assess if these kokanee are descendant from a single or multiple sockeye populations and to test for evidence of recent gene flow between the two forms. Our results should further elucidate the origin of kokanee and their evolutionary relationship to sockeye.