Abstracts (first author)
Heterogeneous genomic differentiation in marine threespine sticklebacks: adaptation along an environmental gradient
Recent years have seen a shift in the way we view population structuring in organisms living in marine environments. Once thought of as panmictic and genetically homogenous, marine populations are now realized to have the potential to be subdivided on a finer geographic scale than previously appreciated. Descriptions of variation at genes whose functional roles are associated with specific selection regimes can offer insight towards the scale and degree of adaptive divergence among marine populations, but until recently this approach has traditionally been limited to very few loci. In our research, we use a genome-wide set of 140 microsatellite markers that are within (or close to) genes that have exhibited transcriptional responses to specific environmental conditions, in order to explore the patterns of adaptive population divergence and heterogeneous genomic differentiation among marine threespine sticklebacks (Gasterosteus aculeatus) in Northern European seas. Using 20 of these markers and a much denser sampling scheme, we then further explored adaptive divergence within the environmentally heterogeneous Baltic Sea in relation to the steep salinity and thermal gradients. The results of our candidate genome-scans provide support for the emerging view that, in spite of the high degree of physical connectivity in marine environments, there is a great deal of adaptive divergence among marine populations that is not apparent when neutral loci are analyzed.