Reproductive isolation in passerines

I am working with Matt Carling at the University of Wyoming for my PhD.

I am attempting to determine if divergence in various traits between closely related sympatric songbird species can predict whether those species will hybridize or not. Many species of passerines hybridize–but others do not, despite having range overlap, similar songs, and even similar habitat requirements. Can we predict anything about whether reproductive isolation has occurred upon secondary contact among passerines, or is each species-pair different?

To address this question, I am using a comparative approach across several pairs of closely related species that hybridize, and pairs that could (are sympatric) but do not. I am constructing niche models from eBird observations, quantifying song divergence using recordings archived at the Macaulay Library, and measuring plumage characters for each species. I compile these measures into divergence measures for each species-pair, which I then regress against level of reproductive isolation in order to determine if there are any patterns. One of my dissertation chapters examines the relationship between these species traits and hybridization for comparisons across several songbird families. Another chapter focuses more in-depth on the family Cardinalidae–a really cool family with several hybridizing species.

I will also use this comparative framework to try to understand patterns in genome-wide divergence. Divergence may be due to selection, but it may also simply be due to lack of recombination in those regions of the genome. Comparison of several species across a single family, and comparison of species-pairs that hybridize or are reproductively isolated, may help us interpret the significance of divergence patterns across the genome. I am comparing species in Passerina and Cyanocompsa for this project.

Behavioral ecology of gulls

During the course of my BS and MS degrees at Andrews University I worked with the Seabird Ecology Team, spearheaded by Jim Hayward and Shandelle Henson. Jim is a behavioral ecologist who has spent years studying the fauna of Protection Island NWR in Washington. This refuge was protected because it hosts the Pacific Northwest’s largest colony of Rhinoceros Auklets. It also hosts a large gull colony: Glaucous-winged Gulls, Glaucous-winged x Western Gull hybrids, and a very few Western Gulls. (We often just call them Glaucous-winged Gulls for simplicity.) I participated in nest monitoring, behavior scan counts, and various small projects during four field seasons on Protection Island.

For my M.S. thesis I compared reproductive success of pairs of gulls spanning the hybridization spectrum, as determined by a hybrid index composed of plumage and bare-part color scores. I found that pairs across the hybrid spectrum did not have significant differences in reproductive success.

Mathematical modeling of animal behavior

A great strength of the Seabird Team was the interdisciplinary work done by Jim, behavioral ecologist, and Shandelle, mathematical ecologist. Shandelle taught me to build models of animal behavior as driven by abiotic, ecological factors; introduced me to programming in Matlab; and showed me the joys of generalized linear regression.

Projects I participated in included modeling gull behavioral states, pigeon guillemot occupancy, and marine iguana haul-out.