2.2 Molecular methods
DNA was extracted from tissue in accordance with a Chelex 100 method (Sigma-Aldrich, St Louis, MO). All specimens were genotyped with genotyping-in-thousand by sequencing method (GT-seq; Campbell et al., 2015). All samples and loci with ≥ 10% missing genotypes were removed from further analyses for quality control purposes. Over the period that these individuals were genotyped, various genetic marker panel updates occurred, resulting in slight variances of the mix of putatively neutral and adaptive markers available (Appendix S1 Table S1). Samples were genotyped with GTseq panels ranging from 368-390 SNPs, and genotype data were retained when >90% loci successfully genotyped and had an estimated <0.5% genotyping error based on replicate genotyping.