Date of Award

Fall 2000

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Alan H. Savitzky

Committee Member

John R. Holsinger

Committee Member

Robert K. Rose

Committee Member

William Resetarits

Call Number for Print

Special Collections LD4331.B46 M333

Abstract

Ambystoma mabeei is listed as threatened in Virginia due to its rarity and susceptibility to urbanization and poor forestry practices. The goal of this study was to identify factors that may affect the persistence of A. mabeei in Virginia by studying the life history and ecology of A. mabeei and its syntopic congener A. opacum. This information will contribute to the knowledge of life history variation within Ambystomatidae and will be critical for the development of a comprehensive management plan for A. mabeei. Population sizes of the two species and the proximate factors responsible for initiating breeding migrations were determined by a mark-recapture study. Salamanders were captured using drift fence and pitfall trap arrays installed in three independent sections encompassing approximately 65% of the pond's perimeter. Analyses of covariance (ANCOVA) were used to compare mass relative to snout-vent length as an index of physiological condition. An analysis of gut contents indicated that A. mabeei consume a variety of prey and individuals from Virginia harbor high loads of gastric parasites.

The results of this study support the hypothesis that environmental conditions influence the breeding migrations of Ambystoma mabeei and A. opacum. The intensity and timing of each migration event are influenced by weather conditions prior to the onset of the breeding season. Adult condition and reproductive success are influenced by annual climatic patterns as well. A model is proposed that explains the migratory patterns observed during this study. This model incorporates both a heritable migration cue and seasonal variation in adult condition. The presence of a genetic determinant for breeding migration provides a mechanism by which adaptation to changes in local environmental conditions can occur. Before we can understand the true status and fate of Ambystoma mabeei in Virginia, additional research into several major areas of the species life history is needed. These studies should address the community ecology, landscape ecology, parasitology and physiological ecology of both the larvae and adults.

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DOI

10.25777/qsaq-qp49

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