Meeting Abstract
Color polymorphism (when two or more discrete color types co-occur in a population) is prevalent in nature and present among various types of traits for different species. These different traits can be subjected to alternate types of selection and can exhibit variable evolutionary dynamics. Because a single species often exhibits only a single trait type, disentangling the role of organism-specific and more general evolutionary forces in driving color polymorphism can be challenging. We leveraged the coral-snake-mimicking western ground snake, Sonora semiannulata, which has both mimetic and non-mimetic polymorphic traits, to test whether these two types of traits exhibit different patterns of spatial variation. Using 308 specimens from 30 populations spanning the geographic range of this species, we scored each individual based on the presence or absence of 1) a red dorsal stripe or black crossbands (mimetic traits) and 2) a black cap or black nuchal band (non-mimetic traits). Both mimetic and non-mimetic traits varied widely across the landscape, with some populations exhibiting all possible morphs and others exhibiting only one. We found that mimetic trait diversity was positively correlated with non-mimetic trait diversity among populations, both when analyzed using Shannon’s diversity indices (p=0.05; R2=0.51) and when using number of morphs (although not significant, p=0.07; R2=0.23). These findings reveal similar spatial patterns of color diversity in both mimetic and non-mimetic traits. More broadly, our results suggest that polymorphism in mimetic and non-mimetic traits is evolutionarily linked in ground snakes, with either similar selection among populations or genetic linkage between these two types of traits.
