System Atics of the Holarctic Chipmunks (Tamias)

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Abstract
Electrophoretic data for 20 proteins were obtained from 17 species of chipmunks, including all three presently recognized subgenera. Average heterozygosity was higher than for ground squirrels (Spermophilus) but was generally within the range reported for other rodents; Tamias minimus, however, had a higher heterozygosity value than almost any other rodent species. Cladistic analyses of the electrophoretic data resulted in species groupings which differed from traditional analyses of morphological data. The species T. Sibiricus and T. striatus were grouped together, separate from all other chipmunks, thereby contradicting traditional supra-specific classifications. We recognize one genus (Tamias) with two subgenera, Tamias (composed of Sibiricus and striatus) and Neotamias with five species groups. A hypothesis concerning dispersal in the ancestral chipmunk lineage was formulated and a phylogram constructed on the basis of cladistic and biogeographic analyses. Multivariate analyses then were conducted on cranial and body measurements of 53 taxa of chipmunks, representing all recognized species and subgenera. Variation among individual taxa was detected in both general size and cranial shape. Phenetic morphological relationships among the chipmunks were ascertained by cluster analysis. The proposed phylogenetic groupings were compared with the morphological groupings in an assessment of divergent and convergent evolution within the genus.