Population structure of Nearctic fishes

Pleistocene glaciation profoundly affected the evolution and biogeography of the Canadian aquatic fauna. In some cases, marine lineages were carried inland by glacial advances and evolved into distinctive freshwater forms that survive today in deep, cold lakes.

from McPhail and Lindsey (1970)

In collaboration with scientists across Canada, our lab is investigating the evolution of Myoxocephalus thompsoni, the deepwater sculpin, a species thought to be a glacial relict. M. thompsoni is distributed from the Laurentian great lakes, through Manitoba and Saskatchewan, to Great Bear Lake in the Northwest Territories. Its hypothesized sister taxon is the fourhorn sculpin (Myoxocephalus quadricornis), distributed in arctic marine waters.

Myoxocephalus thompsoni

We are using mitochondrial DNA sequences, microsatellites, and AFLP markers to assess the relationship of M. thompsoni to the other Myoxocephalus species, and to assess the population genetic structure of M. thompsoni over its range in Canada. These data will be used to determine: (1) whether the deepwater sculpin originated during the most recent glacial advance, or was the product of earlier events, and (2) whether the deepwater sculpin represents a single invasion of freshwater, or multiple colonization events. Our data will also clarify the population genetic structure of the species, providing crucial information for management and conservation.

Tommy Sheldon is conducting his graduate research on the deepwater sculpin. Collaborators include Nick Mandrak, Great Lakes Laboratory for Fisheries and Aquatic Science, DFO (email: MandrakN@DFO-MPO.GC.CA), Chris Wilson, Aquatic Biodiversity and Conservation, OMNR, and Jim Reist, Freshwater Institute, DFO (email: reistj@dfo-mpo.gc.ca).

[click on the images below]