Office: Greeley Laboratory, Room 127
Phone: (203) 432-5321
Fax: (203) 432-3929
||Fine Arts - Music
|St. Michael's College, VT
|| Forestry & Env. Studies
||Forestry & Env. Studies
My research interests lie at the intersection of ecology and evolutionary biology. While these two disciplines have been viewed traditionally as distinct approaches to explaining the natural world, biological organisms know no such divide. To advance our knowledge beyond this constructed dichotomy, I incorporate theoretical and applied insights and approaches from both of these disciplines to answer questions about the responses of organisms to our ever-changing environment.
I investigate both the demographic and evolutionary consequences of human land use on wildlife. This research approach is aimed at developing our insight into the long-term impacts of land development so that we may better understand the fate of species in human modified landscapes. Consistently, this research indicates that the response of species to human land use varies with respect to population origin, even at microgeographic scales. These results are consistent with patterns of population differentiation, indicating that species level investigations are too coarse a filter to resolve contemporary responses. This suggests that predicting species’ responses to land development depends critically on our ability to identify and investigate biologically important levels of organization, such as that of the local population.
I pursue a combination of field and laboratory experiments coupled with observational field studies. I focus my research on ephemeral wetlands located in both northeastern Connecticut at the Yale-Myers Forest and southern New York at the Mianus River Gorge Preserve. The dynamic hydrology of ephemeral wetlands generates a unique class of habitat that hosts a suite of biological organisms found nowhere else. Key characteristics such as annual explosive breeding behavior and small-scale population structure make the amphibian species in this system ideally suited to answering questions that lie on the frontier of understanding the interaction of the natural world and the human enterprise. As well, these species posses the charisma and good looks to get most anyone fired up about life in ephemeral pools!
1. The evolutionary ecology of roads and amphibians
Human modified landscapes are widespread, and the attendant network of roads is similarly vast. Roads contribute a suite of ecological effects including road-kill, dispersal impairment, and contamination from runoff. In the northeast, as with many temperate regions, road maintenance in the winter involves the de-icing of frozen precipitation. Road salt—as the primary de-icing agent used in the North America—is highly prevalent in road runoff and consequently in road-adjacent aquatic habitats.
I am investigating the effects of roads on pool dwelling amphibians—especially wood frogs (Rana sylvatica) and spotted salamanders (Ambystoma maculatum)—using a combination of reciprocal transplant field experiments, road salt exposure experiments, and observational field surveys. The outcome of these experiments and observations indicates that roads and road salt negatively influence wood frogs and spotted salamanders. Importantly however, the degree of influence varies with respect to the origin of the population. Specifically, individuals originating from roadside populations consistently show reduced performance as compared to those originating from woodland populations just hundreds of meters away.
These results paint a surprising picture of the differential influence of land development with respect to local population origin. The populations most susceptible to the influence of road adjacency may be those least capable of persisting there. The patterns revealed so far suggest that roadside populations may 1) attract less capable breeders, 2) induce strong inherited environmental effects, and/or 3) induce responses to selection at later life history stages. Resolving these potential outcomes forms the focus of my future research.
2. Road runoff in ephemeral wetlands
In collaboration with Joseph Bushey (University of Connecticut), I am investigating contaminant cycling in ephemeral wetlands. Together, we are interested in understanding the availability and uptake of a suite of contaminants found in the temporary surface waters that comprise ephemeral wetland habitat. We are especially interested in understanding the cycling of heavy metals (e.g. mercury), nutrients, and ions, and how these chemical species interact under the influence of road proximity.
Due to the shallow depth and small size that is characteristic of ephemeral wetlands, contaminants accumulate in these water bodies at high concentrations. Early results indicate that some contaminants in road-adjacent wetlands are present in concentrations well above toxic thresholds. Using an eco-evolutionary approach, we are evaluating the long-term responses of wetland amphibians to these contaminants by investigating a combination of water samples, tissue analysis, and demographic and performance measures.
3. Pharmaceuticals in the environment
Our understanding of the long-term impacts of pharmaceuticals and their byproducts in the environment is nascent. What is clear is that substantial portions of the pharmaceuticals we ingest are passed through us, and migrate into surrounding ground and surface waters. In collaboration with Susan Bolden (Yale University), David Griffith (MIT/WHOI), and David Skelly (Yale University), I am interested in understanding the distribution of estradiols in permanent wetlands, and their subsequent biological uptake and ecological consequences.
4. Host parasite ecology
Echinostomes are multi-lifecycle trematodes known to parasitize hosts (two intermediate and one definitive) across multiple trophic levels. In this system, freshwater snails play the role of primary intermediate host, while frogs (or even other snails) act as secondary intermediate hosts; mammals and birds comprise the category of definitive hosts. Members of the Skelly lab recently conducted a study of echinostome infection in green frogs (Rana clamitans), which demonstrated a positive correlation between urbanization gradient and infection rates: 99% of total infections were found in frogs originating from urban wetlands. This study indicates that snail density increases with urbanization and predicts echinostome infection rates. However, the question remains: what mechanisms associated with urbanization generate the observed infection gradient?
In order to address this question, I am currently conducting research to identify definitive echinostome hosts acting in Connecticut permanent ponds. Using a suite of methodology, including frog and snail sampling, avian point-counts, mammal detection stations, and GIS analysis, I hope to better understand species assemblage across an infection and urbanization gradient. In collaboration with Manja Holland (University of Michigan), I am screening candidate amphibian hosts for trematodes to investigate the relationship between hosts, infections, and land use.
5. Variation in nature
The ecological paradigm is stretching. Increasingly, we are recognizing that patterns detected at small, tenable scales may bring little to bear on the mechanisms of nature. In his Robert H. MacArthur Award Lecture (1992), Levin argues that identifying relevant scale is one of the greatest challenges in ecological studies. Thus, a key step toward advancing our understanding of nature involves parsing the levels at which variation in the environment and species interact most strongly.
Ecology among scientific disciplines is argued by some to carry the uniquely profound burden of context dependency, and thus is rebuff to general laws that characterize success in other scientific disciplines. Still, others believe that general laws in ecology exist, but remain veiled due to shortcomings in research. Yet, others might argue that the realm of ecological inference lies at the crossroads of intermediate scales, and that a multi-dominance of scales generates complex patterns that are recalcitrant to high degrees of explanation. As a step in unraveling the position of ecological understanding, I am interested in quantifying variation and scales of inference across major scientific disciplines.
First and foremost, my wife, Amy, has put in more than her share of time dipping around swamps, recording tadpole observations, and constructing field enclosures. So hat's off! Amy and I are overjoyed by our daughter Sela Lucille, whom we welcomed into the world November 2009. We have been thrilled as first-time parents introducing Sela to our passion for the outdoors, especially climbing and skiing.
An afternoon with evolutionary ecologist Steve Brady.