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 populati on extinction we studied genetic variation in the root vole, Microtus oecon omus. In The Netherlands the root vole is a species that has become endange red because of severe habitat reduction. Root vole populations across north -west Europe have been studied using 29 allozyme loci. The low levels of ge netic variation found in this study are discussed and are thought to be the result of multiple bottlenecks in population size during the last Pleistoc ene glacials in combination with bottlenecks resulting from population fluc tuations. No significant departures from random mating were found, indicati ng that inbreeding currently does not pose a major problem for the larger p opulations in The Netherlands. However, isolation between populations seems to be substantial, indicating that problems may arise in the near future a t least for small populations, unless appropriate nature management measure s are carried through. (C) 1998 Elsevier Science Ltd. All rights reserved.