Document: JOS-3-52-34

Parasitism and the distribution of pond breeding amphibians.

KIESECKER, J.M.*

Pennsylvania State University, University Park, PA 16802 ¹

Abstract:
Understanding the role that infectious diseases play in natural communities is one of the key questions in community ecology. In spite of the potential significance of disease agents influencing community structure, little is known about how parasitic infections and other known important factors (e.g. competition, predation, disturbance) may interact to modify community structure. Communities composed of larval amphibians and their predators have become a model for understanding the interrelationship among physical and biotic agents structuring the patterns of abundance and distributions of animals. This understanding is grounded on the firm base of experimental findings that have emphasized the role of the permanence of aquatic habitats. Specifically, these experiments show that the timing of pond drying, competition for food, and predation can all have important effects on tadpoles. Unfortunately, no attempts have been made to incorporate how other factors, including parasites, may influence distributional patterns. Here, I report the results of a set of experiments designed to determine how digenetic trematode infection might act selectively to limit distributions of amphibians. I measured the performance of wood frogs (Rana sylvatica), spring peepers (Pseudacris crucifer), gray treefrogs (Hyla versicolor) and green frogs (Rana clamitans) in response to infection by several snail-trematode combinations. I asked whether growth rate differed between tadpoles growing in the presence of infected versus uninfected snails. The answer differed for the species tested and trematodes species to which they were exposed. The results suggested that species living in one pond type (e.g. temporary) perform relatively poorly when in the presence of trematode infection from another pond type (e.g. permanent). Taken together, these results suggest that in addition to strong gradients in hydro-period, predation and competition, differences in infection may contribute to amphibian distributional patterns.

Keywords: Amphibians, Communities Structure, Infection, Parasites, Trematodes.

This abstract is being presented at: 11:15 AM in session:
Oral Session #38: Amphibian Ecology.