Are genetic differences between eastern and western golden-crowned kinglet populations correlated with environmental variation?

Species with broad distributions often inhabit different habitats across their range, and studying how the observed environmental variation influences genetic variation can provide insights into the forces that drive population differentiation. Examining the relationship between genetic and environment variation is of importance given the effect climate change has on natural populations. Here we use high throughput sequencing to assess population structure and examine the relationship between genetic and environment variation in eastern and western populations of Golden-crowned Kinglets (Regulus satrapa; Lichtenstein, 1823) with 14,438 SNPs from 41 individuals. Our analyses revealed that eastern and western populations of Golden-crowned Kinglets are differentiated from each other (FST=0.08; p<0.001), matching results from previous studies, and show low to moderate ecological variation (Cohen’s D=0.52-2.59) for the three environmental variables we measured. The variable examining precipitation showed a moderate correlation with genetic variation (r=0.47; p<0.001) and partial-redundancy and latent factor mixed models identified loci associated with precipitation. These results indicate the potential for environment to drive genetic differences between genetically distinct populations, although isolation by geographic distance during the last glacial maximum appears to have had a stronger effect on population structure. Overall, our study demonstrates the importance of examining genetic and ecological variation in unison to gain greater insights into how environmental variation contributes to genetic variation.