Global selection at SNP loci
The global G’ST values for 9 microsatellite and
101 SNP loci across the six populations (221 individuals) were 0.203 and
0.0393, respectively. Per-locus G’ST values
ranged from 0.0454 to 0.535 for the microsatellite markers, and from
-0.0789 to 0.267 for the SNP markers. Global differentiation patterns
showed 94 out of 101 SNP loci to be consistent with stabilizing
selection, as their level of divergence was lower than the neutral
expectation (Figure 3; Supplementary Material S7). The seven remaining
SNP loci showed divergence levels consistent with neutral processes
(Figure 3; Supplementary Material S7). The SNP loci showing a global
neutral pattern of divergence belonged to four gene function categories:
immune response (1 SNP); lipid metabolism (2 SNPs); nervous system
development (1 SNP) and reproduction (3 SNPs). We did not detect any SNP
loci showing a population divergence pattern consistent with divergent
selection across all six populations (i.e., globalG’ST values), possibly due to inconsistent
patterns of selection acting among the populations, making a pairwise
analysis important to assess divergence patterns.