Hardy-Weinberg equilibrium (HWE) statistics.

‘Exact test’ statistics for each locus, and for each of the 28 populations included in the study (each column represents a population with sample size in the top row, with the populations occurring in the same order, left to right, as numbered in Figure S1 and Table S1), after a sequential Bonferroni correction for multiple tests [43]. Dark shading indicates significant deviation from HWE (chi-squared test, p<0.05); light grey shading indicates monomorphic loci, or only a single copy of a second allele if present. For loci with less than five alleles the complete enumeration method was used [51] but for all others a Markov chain algorithm was implemented [52] in GENEPOP v.4.1 [37].