Project name: Gasterosteus aculeatus

Description: Manuscript abstract:The outcome of selection on genetic variation depends both on the geography of individuals and populations, and the ‘geography’ of loci within the genome. In the threespine stickleback, spatially variable selection between marine and freshwater habitats has had a significant and heterogeneous impact on patterns of genetic variation across the genome. When marine stickleback invade freshwater habitats, more than a quarter of the genome can respond to divergent selection, even in as little as 50 years. This process largely uses standing genetic variation that can be found ubiquitously at low frequency in marine populations, can be millions of years old, and is likely maintained by significant bidirectional gene flow. Here, we combine population genomic sampling of marine and freshwater stickleback from Cook Inlet, Alaska, with genetic maps of stickleback fish derived from those same populations to examine how linkage to loci under selection affects genetic variation across the stickleback genome. We find that divergent genomic regions co-localize with regions of reduced recombination, but that this pattern varies across different genetic maps. Linkage to loci under divergent selection had opposing effects on variation on chromosomes from marine and freshwater fish, and we attribute this effect to differences in population structure between the two habitats. These findings advance our understanding of how the recombination landscape facilitates and structures genomic divergence, and how the structuring of populations across geography can change the outcomes of selection.

Data type: raw sequence reads

Sample scope: Multiisolate

Last updated: 2018-11-30