MAJOR HISTOCOMPATIBILITY COMPLEX MONOMORPHISM AND LOW-LEVELS OF DNA-FINGERPRINTING VARIABILITY IN A REINTRODUCED AND RAPIDLY EXPANDING POPULATION OF BEAVERS

Less of genetic variation due to population bottlenecks may be a sever e threat for the survival of endangered species. Assessment and mainte nance of genetic variability are thus crucial for conservation program s related to endangered populations. Scandinavian beavers went through an extensive bottleneck during the last century due to over-hunting. In Sweden the species became extirpated but in Norway extinction was a voided by legal protection. Following reintroductions of small numbers of remaining Norwegian animals in 1922-1939, the Swedish population h as increased tremendously, now harboring 100,000 animals. We show here that this viable population of beavers possesses extremely low levels of genetic variability at DNA fingerprinting loci and monomorphism at major histocompatibility complex (MHC) class I and class II loci. A s imilar pattern was also evident among Norwegian beavers but low levels of genetic variability were not a characteristic of the species since Russian conspecifics displayed substantial DNA fingerprinting polymor phism. However, the Russian animals were monomorphic at MHC loci, indi cating that the European beaver is exceptional in its low level of MHC variability. The results demonstrate that a conservation program can be successful despite low levels of genetic variation in the founder p opulation.