The Molecular Ecologist: Fishing for genetic signals of adaptation

Atlantic Salmon

Adult Atlantic salmon. (Flickr: Matt Hintsa)

Over at The Molecular Ecologist, I discuss a new paper that exemplifies how we’re going to be studying the genetics of adaptation in the age of high-throughput DNA sequencing—even if it doesn’t quite live up to that promise. It’s a study of adaptation in Atlantic salmon, whose lifestyle makes them uniquely suitable for a particuar sampling design:

Salmon hatch in freshwater rivers, and spend at least their first year in that environment before swimming downstream to the ocean, where they develop into reproductively mature adults. When they’re ready to mate, they migrate back from the ocean, up the river where they hatched to spawn at the site of their birth. Those major migrations and the transitions between freshwater and salt-water are likely to be major selective events for salmon, and they offer convenient times to catch and study salmon from roughly the same age-cohort: when they migrate downstream to the ocean, and when they return to their birth-river.

By taking genetic samples of juvenile salmon on their way out to sea, and then adults on swimming upstream to breed, you can test for genetic changes—adaptation—that has occurred over the course of the fishes’ life in the ocean. And that’s exactly what the authors of this paper did—go read the whole post to find out how it worked.