Dissertation Research: Synergistic Effects of Predators and Trematode Parasites on Larval Amphibians

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Both parasites and predators can affect animals in a variety of complex ways in addition to directly affecting survival and reproduction. For instance, parasites can change how susceptible their hosts are to predators by affecting host behavior or other traits. Similarly, prey that sense a predator is near through visual or chemical cues (e.g., smell) may change their behavior, which may affect their susceptibility to parasites. Such complex effects can impact each species within a community differently, which may benefit some species at the expense of others. As a result, an animal community affected by the combination of predators and parasites may look very different than a community affected by only one type of these natural enemies. This project will evaluate how echinostomes (a trematode parasite) and predators interact to affect larval frog (tadpole) communities in ponds. First, the susceptibility of different species of larval frogs to echinostome infection in the presence and absence of predators will be measured. Second, the interactive effects of predators and parasites on a simple community of larval frogs will be examined. An experiment in artificial ponds will demonstrate the extent to which parasite infection rates depend on the composition of the amphibian community and the presence of predators. The results will also reveal how the combination of infection and predator cues affects competition for resources among larval frogs. Finally, a field survey will suggest how these effects play out in natural ponds in Southeast Michigan. This research will thus provide new insights into complex mechanisms through which parasites and predators affect communities. The outcome will be valuable from a conservation perspective because echinostomes are present at higher levels in areas associated with human impacts, such as pollution and urbanization. Because predators have a strong impact on amphibian communities, their interactions with parasites in these ponds will be particularly important to understand. Additionally, amphibians are a class of special concern because many populations are in decline globally, in part due to disease. This research will involve collaboration with local organizations, undergraduate students, K-12 organizations, and landowners, which will provide an excellent opportunity for public outreach and education.