Research in my lab focuses on understanding the patterns and mechanisms underlying speciation in adaptation in birds. Our work spans the fields of phylogenetics, phylogeography, population genetics, spatial ecology, and more recently, evolutionary physiology. All of this work is integrated within an active museum community.
Environmental heterogeneity and hybridization
Over the past few years, we have used hybrid zones between closely related bird species to test hypotheses related to the underlying genetic mechanisms of the generation and maintenance of reproductive isolation. Increasingly, we have sought to combine population genetic data with environmental data to investigate how heterogeneity in the environment may influence hybrid zone dynamics. While much of this has exploited the hybrid zone between Indigo (Passerina cyanea) and Lazuli (Passerina amoena) buntings, we are also pursuing similar lines of research using the hybrid zone between Red-breasted (Sphyrapicus ruber) and Red-naped (Sphyrapicus nuchalis) sapsuckers as a model. The sapsucker work is being spearheaded by PhD student Shawn Billerman. In addition, along with collaborators Garth Spellman (Black Hills State University) and Ben Zuckerberg (University of Wisconsin), we’re beginning to investigate the influence of environmental variation on hybrid zone dynamics in a much larger comparative framework, which will include a variety of hybridizing avian taxa.
Mechanisms of hybrid breakdown
Along with Zac Cheviron (University of Illinois), we’re in the initial stages of work focused on investigating the mechanistic basis of hybrid breakdown in birds. We suspect that in some cases, hybrid individuals may suffer reductions in whole-organism metabolic performance as a result of mito-nuclear incompatibilities. These disruptions in energy metabolism may then have consequences for hybridization dynamics among avian hybrid zones given geographic variation in the intensity of selection on metabolic performance.
Parasites and reproductive isolation
Largely driven by MS student, Matt Jones, we have begun working on the role that adaptation to local parasite communities may play in diversification among populations of widely-distributed bird species. For example, we have discovered that the rate of Rufous-collared Sparrows (Zonotrichia capensis) infected with avian malarial parasites peaks in populations found at mid-elevations in the Peruvian Andes. Local adaptation to the parasite community at mid-elevations may result in selection against immigration into mid-elevation populations from either high or low-elevation populations, which could then lead to population differentiation.