Genetic monitoring of Eurasian beaver (Castor fiber) in Switzerland and implications for the management of the species

Eurasian beaver (Castor fiber) has been reintroduced in Switzerland between 1956 and 1977. Individuals from the refugium population in France (C. f. galliae) were released in the Rhone catchment area and in tributaries of the Rhine catchment area in Western Switzerland. Individuals from the refugium populations from Norway (C. f. fiber) and Russia (C. f. orientoeuropaeus) were released in tributaries of the Rhine catchment in Eastern Switzerland. In the Rhine basin beavers of different origins came into contact. This study provides a first evaluation of the reintroduction program of beaver in Switzerland and gives implications for the post-release genetic management of the Swiss beaver population. We report on the genetic monitoring of the beaver population in Switzerland, based on the analysis of 251 dead found individuals collected from 1998 to 2014 and a combination of mitochondrial and nuclear genetic markers. We found no evidence of the presence of North American beaver (Castor canadensis) and we observed three mitochondrial DNA haplotypes, assigned to the refugium populations in France (C. f. galliae), Norway (C. f. fiber) and Germany (C. f. albicus). Based on the analysis of seven microsatellite loci, we inferred that the beaver population in Switzerland consists of two genetic clusters and we found evidence of a zone of secondary contact. We observed low levels of genetic diversity and we could show that individuals separated by distances up to 50 km were closely related.