The Effect of Relatedness on Spacing Behavior and Fitness of Female Prairie Voles

Abstract

Numerous behavioral hypotheses have been suggested to explain population cycles in microtine rodents. Charnov and Finerty (1980) proposed that preferential behavior toward relatives drives population cycles through kin selection. Their hypothesis makes three assumptions: (1) individuals behaviorally discriminate kin from non—kin, (2) kin associate, and (3) kin benefit from this association. These assumptions were tested in female prairie voles (Microtus ochrogaster) in eastern Kansas. An equal number of laboratory—born females and males were released into 12 fenced enclosures; 6 enclosures contained groups of littermate sisters and 6 contained groups of unrelated females. Space use, reproductive success, and survival were monitored during two replications of the experiment (Fall 1989 and Spring 1990). Female survival and reproductive success were not affected by relatedness, although more young were born in the Spring than in the Fall. Home range size and overlap were greater for females in related groups than those in unrelated groups. Home range size also was larger in the Fall than in the Spring. Prairie vole sisters associated spatially, but our measurements showed no fitness benefits conferred by these associations. Although the kin—selection hypothesis could not be demonstrated in this experimental population, relatedness in local neighborhoods may have consequences for small mammal population ecology.