Geographic Variation In The Morphometrics Of Emydoide blandingii

Abstract

Morphometric measurements were taken from museum specimens Emydoidea blandingii. Samples were taken from Michigan, Wisconsin, Illinois, Iowa, Nebraska, New York and Minnesota as well as from Ontario, Canada. Populations of this species have become increasingly fragmented and isolated during the past century due primarily to the urbanization of North America which has included increased road related fatalities and habitat destruction. An examination of physical characteristics was conducted to determine if morphometric analysis could indicate differences among the various populations. Twenty-eight measurements were made and compared to detect physical distinctions between populations. Individuals were then classified geographically based on east (C), west (A), or central (B) emanations from the Great Lakes. Analysis revealed significant distinctions in nuchal width and length indicating that these characteristics are independent of size. Jackknife classification hinted ata discrete relationship peripheral groups A and C suggesting a longitudinal clinal relationship in the population. Regression analysis did not support this finding however, but did show indication of a latitudinal relationship in concordance with Bergmann's Rule of increasing body size with increasing latitude as modified by Ashton and Feldman (2003) to include Chelonians.