For my dissertation, I am working on wagtails, a group of birds that belong to the passerine genus Motacilla. I hope to understand the evolutionary processes shaping plumage diversity in Eurasian wagtails. My preliminary analyses support spatially structured populations that conflict with geographic variation in phenotypes. However, the drastic plumage patterning in wagtails is thought to be involved in sexual selection – so, my genetic SNP data may be at a distinct disadvantage for recovering any underlying signal related to phenotypic diversity. Therefore, I am using a whole-genome approach that will allow me to identify highly divergence regions of the genome.

Left image = White Wagtail breeding distribution, credit L. Shyamal; Right = Yellow Wagtail distribution

Left = White Wagtail breeding distribution, credit L. Shyamal; Right = Yellow Wagtail distribution

Investigating the genetic basis of geographically variable traits in a phylogenetic framework can reveal evolutionary processes driving divergence in response to spatial variation in selective forces. Geographically widespread species are useful systems for investigating heterogeneity in genomic divergence and geographic variation in phenotypes, because they offer comparisons among populations at different stages of the speciation continuum. The rate at which population differentiation transitions into speciation depends upon reproductive isolation, relative effects of selection and drift, the degree of genotypic clustering, the sharpness of geographic clines, and the extent of lineage sorting. Identifying common features across species complexes may provide insight into the fundamental principles guiding the speciation process. Beyond evolutionary processes, exploring plumage pattern at the genetic level will add to the relatively small body of literature on the molecular genetics of plumage patterns. How melanin versus carotenoid pigment genes affect the genomic structure of plumage patterning has never been explored.

Funding: Sigma Xi GIAR, AMNH Chapman Grant, NSF DDIG, British Ornithologists’ Union
Collaborators: Per Alstöm
Presentations: International Ornithological Congress 2014, Tokyo,  Japan & American Ornithological Union 2014, Estes Park, Colorado