Glaciers retreat, stickleback advance: variation in demographic histories of freshwater stickleback populations
When colonizing new habitats, the evolution of populations can be affected by their demographic history and structure, including their effective population sizes and the time and nature of their divergence from an ancestral population. The deglaciation of Southern Greenland following the last glacial maximum offers the opportunity to comparatively study colonization events of fish populations…
As glaciers receded following the last ice age, stickleback fish began colonizing freshwater lakes across Southern Greenland. These demographic changes left a genetic imprint on the populations residing in lakes of different sizes and ages, remnants of that ancient climate shift. Researchers analyzed whole-genome data from 17 lake populations and compared them to a marine population sampled from four fjord sites.
The findings reveal that the divergence of freshwater and marine stickleback populations occurred around 4-13 thousand years ago, coinciding with ice sheet retreat and lake formation. Upon invading these new freshwater habitats, all 17 lake populations experienced a decline in size and increased gene flow between freshwater and marine fish.
Interestingly, larger lakes tended to harbor more genetically diverse populations. This study underscores the role of local geological and landscape factors in shaping the genetic makeup of stickleback populations as they colonized postglacial freshwater ecosystems.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
