Contrasting patterns of single nucleotide polymorphisms and structural variations across multiple invasions
Adaptive divergence is a fundamental process that shapes genetic diversity within and across species. Central to this are concepts regarding how genetic variation arises and remains within a population without being deleterious to individual fitness, and conversely how these different genetic variants may respond to selection. Structural variants (SVs) are large-scale genetic variants within an organism's genome and, because of their potentially large size, can induce important functional differences in the individual's phenotype. Characterising SVs across invasive species will help fill knowledge gaps regarding how patterns of genetic diversity and genetic architecture shape rapid adaptation in response to new selection regimes. In this manuscript we seek to understand patterns in genetic diversity within the globally invasive European starling, Sturnus vulgaris. We use whole genome sequencing of eight native United Kingdom (UK), eight invasive North America (NA), and 33 invasive Australian (AU) starlings to examine patterns in genome-wide SNPs and SVs between populations and within Australia. The findings of our research demonstrate that even within recently diverged lineages or populations, there may be high amounts of structural variation. Further, patterns of genetic diversity estimated from SVs do not necessarily reflect relative patterns from SNP data, either when considering patterns of diversity along the length of the organism's chromosomes (owing to enrichment of SVs in sub telomeric repeat regions), or interpopulation diversity patterns (possibly a result of altered selection regimes or introduction history). Finally, we find that levels of balancing selection within the native range differ across differed across SNP and SV groupings. Overall, our results demonstrate that the processes that shape allelic diversity within populations is complex and supports the need for further exploratory SV classification across a range of taxa to better understand correlations between oft well studied SNP diversity and that of SV.