Survey of melanistic garter snakes by traditional and geometric morphometries

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Authors
Van Leuven, James
Advisor
Grant Hokit
Gerald Shields
Murphy Fox
Editor
Date of Issue
2008-04-01
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Publisher
Citation
Series/Report No.
item.page.identifier
Title
Survey of melanistic garter snakes by traditional and geometric morphometries
Other Titles
Type
thesis
Description
Abstract
Melanism in garter snake populations is a rare and ecologically important occurrence. Melanism can be used to study the function of coloration and the process of genetic drift. Coloration patterns of garter snakes may affect fitness level, influenced by predation and thermal efficiency. It is therefore of interest how and why the melanistic trait is acquired. Along the Missouri river near Townsend, MT, three garter snake morphotypes are found; Thamnophis elegans, Thamnophis sirtalis, and melanistic individuals inhabit the area. While T. sirtalis and T. elegans are well studied, little is known about the melanistic population in this area. The goal of this study is to gain insight into which species the melanistic population belongs to and to gather information for further studies. A total of 81 T. elegans, 23 melanistic, and 20 T. sirtalis snakes were captured from March of 2007 to September of 2007. Morphotypes were compared using traditional and geometric morphometries. I discovered significant differences between T. sirtalis and melanistic morphotypes but less difference between T. elegans and melanistic morphotypes. I conclude that melanistic individuals in the Townsend area are morphometrically more similar to T. elegans than to T. sirtalis.
Sponsors
Degree Awarded
Bachelor's
Semester
Spring
Department
Life & Environmental Sciences