Low genetic differentiation in north-west European populations of the locally endangered root vole, Microtus oeconomus

To learn more about the processes that lead to genetic erosion and population extinction we studied genetic variation in the root vole, Microtus oeconomus. In The Netherlands the root vole is a species that has become endangered because of severe habitat reduction. Root vole populations across north-west Europe have been studied using 29 allozyme loci. The low levels of genetic variation found in this study are discussed and are thought to be the result of multiple bottlenecks in population size during the last Pleistocene glacials in combination with bottlenecks resulting from population fluctuations. No significant departures from random mating were found, indicating that inbreeding currently does not pose a major problem for the larger populations in The Netherlands. However, isolation between populations seems to be substantial, indicating that problems may arise in the near future at least for small populations, unless appropriate nature management measures are carried through. (C) 1998 Elsevier Science Ltd. All rights reserved.