Research

Broadly, I am interested in learning about the processes that have driven and structured biological diversity. I am interested in learning what species are, how we define and delimit species, and how species are related to one another. I am also interested in the formation of species, and the processes that drive the isolation of evolutionary lineages. Although a little less that two million eukaryotes have been described, we are only scratching the surface as to the true number of species present, and I find it incredibly exciting thinking about all the species out there that science has yet to discover and describe.

My Master’s work focused on the systematics and evolution of a genus of trapdoor spiders endemic to California (one species is found in Arizona). The genus Aliatypus contains 14 described species, although genetic data suggests the presence of cryptic lineages that will require future taxonomic work. This group shows very interesting patterns, including a great reduction in size in multiple species, as well as evidence of transvalley migration across the now inhospitable central valley. In addition, cryptic species were detected in one previously described species (A. thompsoni). Multiple genes were sequenced to show that what was once considered a single species, really comprises three species. Although these three species are morphologically very similar, molecular data suggests they have been separated for millions of years. This work led to the formal description of two species new to science!

For my PhD, I transitioned to working on an ecological community centered around the carnivorous pitcher plant, Sarracenia alata. Previous work in the Carstens Lab had identified strong population structure in the plant, as well as phylogenetic structure in the bacterial community found within the pitcher fluid. Early work during my PhD combined sequence data from 21 genes and a wide range of statistical analyses to demonstrate that populations separated by the Mississippi River comprise two separate species, corresponding with those east and of those west of the river. To take this to a community level analysis, I analyzed eukaryotic barcode data recovered from the pitcher plant fluid, and demonstrated that a little more than half the eukaryotes sampled (represented across the Tree of Life) contain population genetic structure congruent with that of the plant, suggesting that present-day ecological associations extend into evolutionary time. Additionally, I generated RADseq data through next-generation sequencing technology for multiple arthropod species and looked at both spatial and temporal congruence of community diversification across the landscape. Results suggest that ecological interaction is positively correlated with phylogeographic congruence, and the pitcher plant community expanded from east-to-west across the Mississippi River delta. Coupled with the development of a new approach for quantifying phylogeographic concordance, this work suggests that species with tightly linked ecological interactions share a common response to landscape processes, providing evidence that co-diversification starts at the population level.

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