Local signatures of founding populations confound examination of adaptive divergence in invasive populations
A detailed understanding of population genetics in invasive populations helps us to identify drivers of successful introductions. Here, we investigate putative signals of selection in Australian populations of invasive common starlings, Sturnus vulgaris, and seek to understand how these have been influenced by introduction history. We use reduced representation sequencing to determine population structure, and identity Single Nucleotide Polymorphisms (SNPs) that are putatively under selection. We found that since their introduction into Australia, starling populations have become genetically differentiated despite the potential for high levels of dispersal, and that selection has facilitated their adaptation to the wide range of environmental conditions across their geographic range. Isolation by distance appears to have played a strong role in determining genetic substructure across the starlings Australian range. Analyses of candidate SNPs that are putatively under selection indicate that aridity, precipitation, and temperature may be important factors driving adaptive variation across the starlings invasive range in Australia. However, we also note that the historic introduction regime may leave footprints on sites flagged as being under adaptive selection, and encourage critical interpretation of selection analyses.