Multi-Locus Adaptation
The RDA using 7 environmental variables identified 77 SNPs significantly correlated with 4 of them (Fig. 5): months > 10 degrees C (37 loci), BIO4 – Temperature Seasonality (26), PET of the warmest quarter (12), and BIO18 – Precipitation of the Warmest Quarter (2). The phenotypic analysis estimated 30 significant associations with 9 variables: ON and FL (6 each); TW and TO (4); and SVL, IC, HL, ED, and CW (2). These primarily reflect body size, head shape, and limb length. Of the significant loci, 18 are shared between the environmental and phenotypic predictors, with 12 related to months > 10 degrees C and limb length or head shape. Of those remaining, 2 SNPs are related to PET of the Wettest Quarter and tail width, and 4 are related to Temperature Seasonality and head shape. Consequently, we conclude that there is a limited but non-zero degree of adaptive genetic differentiation with respect to ecomorphology along axes of temperature, precipitation, and phenotypic robustness. Given the lack of a suitable reference genome, we cannot pinpoint the physical location of these sites.