In this paper, we analyze variation in spectral reflectance and color pattern among populations to demonstrate dramatic divergence between four distinct morphs of the mimic poison frog Ranitomeya imitator. We also analyze genetic divergence in d-loop mtDNA sequences between populations. We then use coalescent-based simulations to demonstrate that the high levels of observed phenotypic divergence are not consistent with levels of genetic divergence expected under neutral drift among populations, implying an important role for selection in driving divergence between these populations. © 2012 Current Zoology.