Patterns of genetic diversity in Diporeia in the Laurentian Great Lakes

The benthic amphipod Diporeia once comprised the majority of the benthic biomass throughout the Great Lakes and was historically the major food source for lake whitefish, rainbow smelt, alewives, and slimy sculpins. Since the early 1990s, Diporeia populations have experienced dramatic declines while commercial fisheries have concurrently experienced a decrease in production. Various mechanisms and agents have been investigated with no conclusive results, although the studies do indicate that some lake regions are experiencing extreme declines while other regions retain static population levels. These confounding patterns suggest that Diporeia \u27s environmental demands for survival differ across the Great Lakes region and it is possible that the disparities in decline can be explained by differences in species composition. To investigate Diporeia\u27s genetic lineages, uncover phylogenetic relationships, and assess population structure across the Great Lakes region, we examined samples collected from 19 sites across the Great Lakes using mitochondrial gene regions identified with the aid of 454 high-throughput sequencing technology. These results indicate that Lake Superior represents a distinct lineage from that of the other Great Lakes. Genetic diversity indices did not display a division between declining and non-declining sample sites which eliminates gene pool deficiency as a plausible explanation for Diporeia\u27s reduction