Geographical coincidence and mimicry between harmless snakes (Colubridae: Oxyrhopus) and harmful models (Elapidae: Micrurus)

Abstract

AbstractAimIn the New World coral‐snake complex, Micrurus species presumably serve as Batesian models for some species of Colubridae, including Oxyrhopus. To better understand the evolutionary role of mimicry, we explored the distributional overlap of Micrurus (models) and Oxyrhopus (mimics), the association between species and pattern richness of both taxa, and the relationship between mimetic fidelity and model diversity.LocationThe Neotropical region and southern‐most Nearctic region.MethodsWe classified colour patterns and delineated the geographical distributions of species in a 1° grid, spanning the distributions of both genera. We used generalized linear models to test for significant associations of species and colour patterns. We used guided regularized random forests to identify, among Micrurus colour patterns, the best predictors of the presence and richness of Oxyrhopus colour patterns. To account for spatial autocorrelation, we implemented Bayesian hierarchical models using the integral nested Laplace approximation with a conditional autoregressive prior.ResultsWith few exceptions, the presence and richness of species of Micrurus bearing a given colour pattern in grid cells were good predictors of the presence and richness of Oxyrhopus species bearing the same colour pattern. However, these relationships did not hold when we accounted for species of Micrurus bearing different colour patterns, except in a few cases. The presence of perfect (i.e. those that have a matching Micrurus model) and imperfect (those that do not) Oxyrhopus colour patterns in grid cells was positively correlated with the richness of Micrurus colour patterns.Main conclusionsMimicry complexes may not rely upon perfect signal matching and distributional overlap as previously supposed. Tests of mimetic relationships based on geographical distributions must account for alternative hypotheses including organisms that do not appear to be close mimics. Mimicry complexes may capitalize upon model signal diversity, allowing for the diversification of lineages with warning coloration in the face of stabilizing selection.