Inbreeding in the field: an experiment on root vole populations

Abstract

We used a field experiment with replicate populations of a particular geographic race of root voles (Microtus oeconomus) with different degrees of inbreeding to test whether inbreeding effects were expressed in demographic parameters. This geographic race had been shown to exhibit reduced reproductive rates in the laboratory resulting from inbreeding depression. There were no effects of inbreeding on population growth rate or any demographic parameter. Inbred animals grew less than outbred animals early in the summer, but this had no demographic consequences. Our study is one of the few to compare the performance of the same species in the laboratory and in the field with respect to the extent of inbreeding depression. More such comparisons will be needed to determine whether inbreeding is detrimental more often in the field than in the laboratory.