Date of Award

4-20-2020

Document Type

Distinction Paper

Degree Name

Zoo and Conservation Science-BS

Department

Biology & Earth Science

Advisor

Dr. Sarah Bouchard

First Committee Member

Dr. Sarah Bouchard

Second Committee Member

Dr. Michael Hoggarth

Third Committee Member

Dr. Robin Grote

Keywords

Leaf Litter, Gray Tree Frog, Predation

Subject Categories

Biology | Zoology

Abstract

Plant litter is an important resource for consumers, particularly in freshwater environments where it influences the development processes of larval amphibians. Leaf litter alters the physiochemical environment by lowering dissolved oxygen while increasing nitrogen, tannin, and phenolic acid levels. Many anuran species show plastic responses to the threat of predation. This is communicated through a kairomone when a tadpole is consumed, allowing surviving tadpoles to alter their behavior and morphology to evade predators. The purpose of this study was to analyze the interactive effects of leaf litter and predation on gray treefrog tadpoles (Hyla versicolor). The chemical output of the leaf litter was manipulated by soaking a subset of each litter type to remove leachates. Larvae were reared in outdoor mesocosms with one of the following leaf litter types: un-soaked red maple, soaked red maple, un-soaked pin oak, soaked pin oak, or no leaf litter. Half of the tanks contained caged dragonfly larvae (Plathemis lydia) predators. We measured elements of water quality, tadpole growth, tail morphology, froglet size, and time to metamorphose. Maple leaf litter reduced water clarity and introduced more nitrogen than oak leaves. Predation decreased growth rate in maple tanks, and increased growth rate in oak tanks. Both maple and oak elicited bigger tails under predation, however larvae in oak leaf litter showed the greatest shift in tail morphology by developing deeper tails under predation. These results suggest the physiochemical properties of maple and oak leaf litter elicit different responses from predation threats. This study has important implications of the physiochemical relationship between leaf litter and predation cues, and the combined effect on the growth and development of Hyla versicolor tadpoles.

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