Deep ecomorphological and genetic divergence in Steller’s Jays (Cyanocitta stelleri, Aves: Corvidae)

The relationship between ecology and morphology is a cornerstone of evolutionary biology, and quantifying variation across environments can shed light on processes that give rise to biodiversity. Three morphotypes of the Steller’s Jay (Cyanocitta stelleri) occupy different ecoregions in western North America that vary in climate and land cover. These morphotypes (Coastal, Interior, Rocky Mountain) differ in size, plumage coloration, and head pattern. We sampled 1,080 Steller’s Jays from 68 populations (plus 11 outgroups) to address three main questions using data on morphology, plumage, genetics (mtDNA, microsatellites), and ecological niches: (1) How do phenotypic and genetic traits vary within and among populations, morphotypes, and ecoregions? (2) How do population-level differences in Steller’s Jays compare to other sister species pairs of North American birds? (3) What can we infer about the population history of Steller’s Jays in relation to past climates, paleoecology, and niche ...