DISSERTATION RESEARCH: Spatial variation in bill morphology and genetic structure in the Island Scrub-Jay: Adaptive divergence within a single-island endemic?

Colorado State University, Fort Collins CO

Investigators

Abstract

The spatial scale of adaptive differentiation and the mechanisms that drive it has been at the forefront of evolutionary debate since Darwin. Because birds can fly, dispersal and gene flow between populations has traditionally been thought to be high, leading to constraints on local adaptation and divergence. Yet, increasingly evidence is accumulating that divergent selection can promote adaptive differences between adjacent bird populations even in the presence of gene flow. Recently, small-scale patterns of adaptive differentiation in bill morphology were detected in the Island Scrub-Jay (Aphelocoma insularis), a species that is confined to a single island in southern California. This work will be extended to test mechanisms hypothesized to facilitate divergence with gene flow, including disruptive selection across habitat ecotones and linkage with traits related to mate choice. Beyond the implications for understanding the scale of adaptive differentiation, the data collected will be used to inform management strategies aimed at conserving the Island Scrub-Jay ? a species that has a total population size estimated at <3000 individuals. Research on this unique insular endemic will also be used to engage the public by creating educational activities for high school students and by further developing and promoting a citizen science program on the island where the work is conducted.