Plumage evolution in relation to light environment in a novel clade of Neotropical tanagers

Molecular phylogenetic analyses have greatly changed Neotropical avian systematics in the past couple of decades. These new phylogenies provide the necessary framework to study the ecology and natural history of species in the region in an evolutionary context. This study addresses the systematics of Poospiza, Compsospiza, Hemispingus, Thlypopsis, and eight monotypic genera, which form a strongly supported and novel clade within the tanagers. We find Poospiza, Hemispingus, and Thlypopsis to be polyphyletic, confirm or reject relationships proposed based on morphology and life history, and describe novel relationships among these and the monotypic genera. The diversity of plumage, habitat, and geography throughout the clade allows us to test hypotheses of plumage evolution in relation to light environment. We find that overall plumage brightness best fits a model that includes selective regimes based on open versus closed habitats and foraging strata, while plumage measures describing color diversity and chroma best fit a model that only includes selective regimes based on open and closed habitats.

Highlights► We describe the systematics of a novel clade of tanagers and tanager-finches. ► We found strong support for paraphyly of Hemispingus, Poospiza, and Thlypopsis. ► We show evidence for plumage evolution based on light environment for both sexes. ► Evolution of plumage brightness follows expectations for selection based on crypsis. ► More colorful plumage is found in closed environments than open environments.