Biogeography & Phylogeography
FIg. 1: Dispersal-vicariance analysis of Metallura in RASP. Pie charts at nodes represent estimates of ancestral distribution for each node. Colors and letters correspond to map.
Fig. 2: PCA analysis of Savannah Sparrow SNP dataset.
A central theme of my research is understanding the historical and ecological processes that shape patterns of population structure. I approach these questions using a range of phylogenetic and population genetic methods on molecular data ranging from mitochondrial DNA to large SNP datasets generated via Next-generation sequencing methods.
Much of this work has focused on Metallura hummingbirds as part of my Master’s research with Dr. Chris Witt at UNM where I examined the history of expansion and divergence in this widespread Andean genus. A key finding was that following divergence between two main clades of Metallura hummingbirds, the widespread taxon M. tyrianthina diversified in the northern Andes and the second clade speciated in the central Andes. These two clades subsequently expanded into secondary contact and underwent extensive diversification during Pleistocene glacial cycles (Fig. 1).
These approaches are also integral to my dissertation work on Savannah Sparrows (Passerculus sandwichensis) with Dr. Zac Cheviron at UIUC/UM. Here I am estimating phylogeographic history of the Savannah Sparrow to estimate colonization history of salt marsh environments along the Pacific coast as well as fluctuations in population size or variation in gene flow among populations. Estimation of colonization history and these demographic parameters lays the foundation for latter aspects of my dissertation exploring how this demographic variation might shape physiological adaptation to the high salinities encountered in salt marsh environments.
Benham, P.M. et al. 2016. Journal of Biogeography 42: 763-777. PDF
Lim, H.C. et al. 2014. The Auk 131: 629-642. PDF