Taxonomy of Sigmodon Hispidus on the Great Plains

Abstract

Taxonomic relationships among populations of Sigmodon hispidus Say and Ord inhabiting the Great Plains were examined using morphometric and electrophoretic methods of analysis. Geographic patterns of neither morphometric nor genic variation correspond closely with the putative ranges of S.h. alfredi, S.h. berlandieri, or S.h. texianus. Historical zoogeographic patterns of the species and the current distribution of variant alleles suggest gene flow on to the Great Plains from both the Mexican Plateau and the eastern United States. The distribution of unique alleles suggests that populations on the western Great Plains may be following their own evolutionary trends. However, genic similarity and gene flow estimates are high and morphological variation is either random or clinal throughout much of the Great Plains. Populations of S. hispidus inhabiting mesic areas of the High Plains of southeastern Colorado show no substantial morphological or genic differences from populations throughout Kansas, Oklahoma, and much of Texas. Therefore, the name S.h. alfredi Goldman and Gardner is relegated to synonymy with S.h. texianus (Audubon and Bachman).