Date of Award

Spring 2020

Document Type

Distinction Paper

Degree Name

Zoo and Conservation Science-BS


Biology & Earth Science


Sarah Bouchard, PhD.

First Committee Member

Jennifer A. Bennett, Ph.D.

Second Committee Member

David G. Robertson, Ph. D.


Leaf Litter, Gray Tree Frog, Organ Size, Microbiome

Subject Categories

Other Ecology and Evolutionary Biology



Leaf litter can influence growth and development of amphibians by providing nutrients, structural support, and chemical leachates to the water. The purpose of this research was to determine the effects of Red Maple, Acer rubrum, and Pin Oak, Quercus palustris, leaf litter on organ size plasticity and microbiome composition in larval gray treefrogs, Hyla versicolor. Larvae were raised in outdoor mesocosms each containing 20 tadpoles. The treatments included: no leaf litter, maple litter, and oak litter. There were also treatments in which leaves were soaked in advance to remove leachates. This separated leaf structure from chemical make-up. Each treatment was replicated four times. To standardize developmental stage, tadpoles were selected based on size. Four size-matched larvae were sampled from each tank for organ analysis and three were sampled for microbiome assessment. Guts, livers, pancreas, fat bodies, and brains were weighed and guts were measured. Guts were also preserved in the -20 °C freezer for analysis of their microbiome. Data were analyzed with linear mixed effects models. There was no effect of leaf litter on growth rate of tadpoles in oak or maple treatments. Analyses indicated that leaf litter has a significant effect on organ size plasticity. The livers of tadpoles reared with oak leaf litter were significantly larger than those reared with maple in both unsoaked (p=0.002) and soaked treatments (p=0.004). Pancreases were larger in soaked oak treatments compared to soaked maple (p=0.01926). Fat bodies in soaked oak were over twice as large as fat bodies found in soaked maple treatments (p=0.0035). Brain mass from soaked maple treatments were larger than those from unsoaked maple treatments (p= 0.0213). There was no difference in brain mass between soaked oak and unsoaked oak treatments. We can conclude that physical and chemical characteristics of leaf litter had an effect on the organ size plasticity of larval gray treefrogs. For instance, soak leaf litter contains more lignin and cellulose, while maple leaf litter decays at a faster rate and contains a higher amount of phenolic acids. Microbiome analyses will be completed when The Genomics Core at Michigan State University reopens post-coronavirus shutdown.