Description
Coloration in male and female birds arises from a complex concert of selection pressures acting upon social signaling traits. The effect of this concert can act on different axes of selection, where males and females are both influenced by natural and sexual selection but not always in juxtaposition. Dissecting how these large forces of selection jointly and independently influence plumage evolution is paramount to understanding how lineages originate and proliferate. However, few studies have attempted to quantify habitat beyond categorical metrics. In this thesis, I explore the interplay between habitat and coloration patterns in Cardinalidae and assess the resulting impact on the evolution of color. My first objective was to generate a new phylogeny of Cardinalidae using genomic-level sequencing. I used ultraconserved elements to infer phylogenetic relationships under both concatenated and multi-species coalescent based approaches. I confirm many previously estimated phylogenetic relationships and identified novel topological relationships, providing a necessary framework to understand how coloration evolves. The second objective was to quantify color and evaluate how habitat and migration influence coloration patterns. I find that male color complexity is linked to semi-open habitats but found no link between habitat structure and female color complexity. Female coloration is influenced by migratory behavior, but male coloration is not, and brilliance in both sexes is linked to light environment. The final objective was to quantify habitat using remote sensing datasets. I assess how ecogeographic variables (climate, land cover, forest cover, vegetation indexes) jointly and independently influence the evolution of plumage coloration in male and female cardinals. I find that female coloration, but not male coloration, is heavily influenced by region-specific habitat constraints. Females that are larger, with higher variation in brown vegetation across their range have evolved to be more colorful, while males are only influenced by climate and foraging strata. My results suggest that sexual selection has powerful effects on the evolution of both male and female coloration patterns, and that female elaborate coloration involves the complex interplay between balancing the pressures of natural and sexual selection.
