Cloudy with a chance of speciation: integrative taxonomy reveals extraordinary divergence within a Mesoamerican cloud forest bird

The highlands of Mesoamerica harbor some of the highest biodiversity in the world, especially in cloud forests, but the landscape drivers of this diversification are not well known. Taxonomy in this region has been challenging due to a lack of consensus about how to test species limits. We apply integrative taxonomy to an emblematic species of the Mesoamerican cloud forests, the Unicolored Jay (Aphelocoma unicolor). We assess divergence along three complementary axes – genetics, phenotype, and ecological niche – finding evidence for differentiation among five lineages, currently described as subspecies, in isolated forest patches. DNA suggests that lineages have long histories of divergence. Multivariate analysis of phenotype, along with an objective method for detecting phenotypic clusters, suggest that at least four of the five lineages are diagnosable. There was also a pattern of increasing ecological divergence through time. The divergence observed among lineages is comparable to ot...