Intraspecific Variation within a Southeastern Population of the Prairie Vole, Microtus ochrogaster (Rodentia)

Abstract

Intraspecific variation in the prairie vole, Microtus ochrogaster, was examined using univariate and multivariate statistical techniques. Twelve morphological characters of 271 specimens collected from 15 quadrats in Arkansas, Missouri and Tennessee were utilized in data analyses. A matrix of correlation of characters was computed and the first three principal components, accounting for 91.1% of the character set variation, are reported. Projections of quadrat samples onto the first three principal components revealed interlocality variability within morphological characters. A general trend for voles being largest in the southern localities and smallest in the northern localities was identified. In addition, significant nonsize differences were noted between voles from localities east of the Mississippi River and those west of the Mississippi. No evidence was found to support the hypothesis of a disjunct central Arkansas population. The prairie vole, Microtus ochrogaster (Wagner), is a widely distributed microtine of the central United States. In the southeast its range includes much of northern and eastern Arkansas and western Tennessee (Hall, 1981). Southern expansion of this species appears to have been rapid and since 1959 it has advanced into south-central Arkansas and across Tennessee into Alabama (Severinghaus, 1976). Sealander et al. (1975) investigated the central Arkansas population of M. ochrogaster and concluded that a disjunct population in the vicinity of Little Rock had morphologically diverged from more northern populations. The purpose of this study was to examine intraspecific variation of cranial characters across the ranges of M. ochrogaster in southeast Missouri, Arkansas and west Tennessee.