How do landscape and species traits influence gene flow and population persistence?
This question is central to management of endangered species and to predicting future change at both the species and community level in fragmented habitats. For my PhD work on turtles in the Midwest, I examined fine-scale gene flow and recruitment in Blanding’s turtles using genetic and demographic data coupled with simulations, revealing a pattern of female natal philopatry and a corresponding pattern of fine-scale variation in population growth in response to habitat restoration. I also used comparisons among freshwater turtle species at a broader spatial scale to examine how species traits and characteristics of both aquatic and terrestrial habitat influence sex ratio, genetic diversity, and genetic isolation. As a postdoc at Michigan State, I developed a hybrid RADseq and sequence capture method to obtain genomic data for thousands of Arkansas darters, with the aim of estimating stream-level effective population size and connectivity across their range. With a Rutgers undergraduate student researcher, I am also working on identifying patterns of sibling dispersal in yellowtail clownfish.
How can past reactions to climate change inform forecasts of future change?
Many of our predictions regarding the effects of climate change on species are based on niche modeling. These projections are useful but potentially misleading, as they often ignore physiological tolerances, species-specific potential for adaptation and range expansion, and interspecies interactions. In my past work, I have examined species’ reactions to past climate change using a variety of methods, including spatially-explicit coalescent simulations of postglacial range expansion across North America (in painted turtles) and hierarchical Bayesian modeling of past demographic change (in marine turtles). I am also collaborating on a crowdfunded project to quantify adaptive genetic variability related to climate across turtle species.
How does genetic diversity and gene flow influence fitness, local adaptation and evolutionary potential?
Gene flow has the potential to reduce fitness by disrupting local adaptation; however, in small populations, the fitness benefits of gene flow (from decreased inbreeding and increased evolutionary potential) can potentially counteract its negative effects. I worked with my former PI, Dr. Sarah Fitzpatrick, to measure changes in additive genetic variation associated with locally adapted traits and individual fitness and responses to environmental stress following gene flow from a divergent source population in Trinidadian guppies. In collaboration with my current PI, Malin Pinsky, and Bastiaan Star (University of Oslo), I have also used temporal genomic data to identify parallel signatures of polygenic adaptation to intense fishing pressure in Atlantic cod from Canada and Norway.
How can museum collections inform our understanding of recent and historic evolutionary change?
Currently, I am working with historical and contemporary collections of ≥20 species of marine fish to identify changes in genetic diversity over the past century as a member of the Philippines PIRE project (read more about the PIRE project here!). This research project will help us to identify recent and historic changes in population size and will inform conservation strategies in this hyper-diverse region. I have also used museum specimens extensively in other aspects of my past and present research. This includes past research at the American Museum of Natural History, where I examined the possibility of gene flow and reticulate evolution among mud turtle (family Kinosternidae) species using molecular and 3-D morphological data.
How do habitat characteristics affect morphology and demography?
Turtles are major players in North American aquatic ecosystems and tend to have extremely high biomass relative to other vertebrates in these systems. With the help of a truly exceptional summer REU student, I have recently initiated a project to revisit a long-term turtle demography study in Michigan. This work has already shown strong differences among environments in population density, growth rates, and carapace morphology. I am currently working with this student to extend this research in order to examine the larger aquatic community in these environments and investigate the potential for differential resource utilization using stable isotope analysis. This research has the potential to identify previously unknown factors regulating turtle population size and morphological features while also better characterizing trophic structure and ecosystem function in aquatic communities.