Research

Given the growing acceptance that evolution by natural selection operates on ecological timescales, I am interested in integrating careful, detailed measurements of natural selection and phenotypic evolution with ecological measurements in order to understand how eco-evolutionary feedbacks shape both evolutionary change and ecological patterns and processes in natural and human-altered ecosystems.

 The thread that ties my basic and applied interests together is the quantification of selection and phenotypic evolution.  In an applied setting I’m interested in the conservation implications of natural and anthropogenic selection for population persistence and full participation in ecosystem function.

Eco-evolutionary dynamics in Threespine stickleback from Bar-Built Estuaries

For my dissertation I will study eco-evolutionary dynamics in polymorphic populations of threespine stickleback (Gasterosteus aculeatus) in bar-built estuaries. Marine or anadromous threespine stickleback have independently colonized freshwater environments and evolved in predictable ways.  Most visibly, marine and anadromous populations are always completely plated (first fish below) while freshwater fish are almost always partial or low plated. In bar-built estuaries along the coast of California, threespine stickleback populations exhibit all three morphs. I plan to investigate whether individuals with different phenotypes (armor and other traits) have different ecological effects, how changes in the relative abundance of different phenotypes (evolution) may effect the estuarine community and ecological processes, and whether those ecological impacts will feedback to alter selection on stickleback.

From top to bottom: Completely, partial, and low plated threespine stickleback. From Barret et al. 2008

From top to bottom: Completely, partial, and low plated threespine stickleback. From Barrett et al. 2008.

Evolutionary Conservation Biology

Using existing data on culvert passage experiments in brook trout, we’re testing whether culverts function as selective barriers for fish with certain body shapes.

Thermal Transgenerational Plasticity

Under the direction of Stephan Munch we’re investigating the effects of parental temperature environment on early juvenile growth using sheepshead minnow (Cyprinidon variegatus).

Past Projects

Evolution of Guppy Foraging Traits Following Predator Release

For my undergraduate thesis I used feeding trials and morphology to test whether resource competition between Trinidadian Guppies (Poecilia reticulata) and Hart’s Rivulus (Rivulus hartii) differed across predation regimes.Rivulus seemed unaffected by predator regime, but guppies varied significantly in their feeding performance.  We found that guppies from low predation sites which had higher population densities also had increased feeding performance.

By testing guppies from a historical introduction experiment we found that after 32 years (or roughly 55 generations) high predation fish introduced into a low predation site had evolved feeding rates and trophic traits intermediate to either natural high and low predation populations. This is in contrast to the original experiment, when it was shown that life histories evolved within 10 years to the norm for low predation environments. We hypothesize that predator release and the increased population density has increased intraspecific resource competition, but that this selection was not as strong as selection on life history traits by predator release.

 Population Dynamics on Heterogeneous Landscapes

We used individual based patch-occupancy models to investigate the impact of spatial heterogeneity in habitat quality on population dynamics and found that with increasing population density the average habitat quality of occupied sites decreased, but that the difference between the variance of the habitat quality of occupied sites depended on the distribution of habitat quality.