A growing network of roads characterizes our natural landscapes. Temporary wetlands are often dramatically influenced by runoff from roads, exposing amphibian species to potentially toxic levels of contaminants. Because populations can vary dramatically in their responses to human altered environments, the ability to predict these responses depends critically on addressing local population level variation. The goal of this research is to examine the long-term consequences of roads on a wetland amphibian, the wood frog. The investigators will combine genomic, histological, and chemical approaches to evaluate local population structure of breeding adult wood frogs with respect to genetic composition, age, and bioaccumulation of runoff contaminants. Insight gained from this approach will significantly advance our understanding of the long-term fate of roadside environments.
This research extends an emerging synthesis of ecology and evolutionary biology while simultaneously addressing a preeminent environmental challenge. The investigators will continue their involvement in the Evolutions after-school program at the Yale Peabody Museum. Evolutions provides after-school exposure to science for inner city youth from New Haven public schools. A portion of funding from this proposal will support semester internships for two high school students in Evolutions. The co-PI will present results to state agencies along with local conservation groups including a land preserve, a wetland society, and the Society of Soil Scientists of Southern New England.
Recent development in the fields of ecology and evolutionary biology have lead to the recognition that evolution can act quickly and influence the ways in which species respond to their environments, leading to changes that are detectable in our lifetimes. We extended this perspective into the context of environments that have been modified by human activities, and asked whether evolution has influenced the ability of amphibians to cope with the consequences of roads. Our previous research has shown that roadside wetlands accumulate high levels of contaminants such as road salt and metals. We have found that wood frog eggs and tadpoles living in these roadside wetlands survive at much lower rates than those living in wetlands located several hundred feet from the road. But what we did not know was whether roadside wood frogs might be evolving in response to these changes in their environment. Here, we investigated exactly that by comparing the influence of roadside wetlands on both types of populations—those originating from roadside wetlands and those originating from nearby woodland wetlands. If roadside populations have responded to evolutionary selection, they should be relatively more capable of surviving in roadside wetlands, as compared to neighboring populations from woodland wetlands. We found that roadside wood frogs are actually less capable of tolerating the negative effects of roadside wetlands than wood frogs originating from woodland wetlands. Our results suggest that exposure to roadside wetlands has a negative effect not only for the eggs and tadpoles that are growing up in roadside waters, but also for the offspring that they will eventually rear. This suggests that the negative consequences of roadside wetlands are inherited from one generation to the next. As a result, the lineage of roadside wood frogs is predisposed to lower rates of survival. These results reshape our understanding of the consequences of roads by revealing that the very populations that are encountering road effects are actually more susceptible to the consequences than nearby populations of the same species. This outcome suggests that population specific approaches such as those employed here will help us develop a fuller and more precise understanding of the ways in which human-altered habitats affect wildlife populations. By unveiling these comprehensive effects, we will improve our ability to predict long-term outcomes and thereby guide our efforts in conservation with more strategic use of resources.
