Genetic diversity analysis of beavers (Castor fiber) in England.
As part of a data gathering exercise, Natural England has commissioned a study to investigate the underlying genetic diversity of beavers (Castor fiber) living in England, UK. This report outlines the genetic analysis that was undertaken on available samples in 2013 from individuals that were licensed for translocation from Tayside, Scotland, to multiple enclosures within England; individuals living on the River Otter, Devon, as part of the licensed reintroduction trial; individuals in Devon not associated with the River Otter Trial and individuals (free-living and in enclosures) in Kent. For each population and enclosure that samples were available for, genetic diversity and relatedness were estimated between individuals. Genetic diversity and relatedness in each population and enclosure were also compared to established populations in Scotland and across Europe. It was shown that beavers were currently residing in multiple locations across at least eight counties in England (free-living and in enclosures). When taken as a country-wide metapopulation, the genetic diversity of beavers currently residing in England were comparable to Scottish and European populations. These individuals have shownancestry from four of the known European fur-trade refugia (Norway, France, Russia and Belarus). There was no evidence for ancestry from the Germany: Elbe (Hesse) fur trade refugia within any beavers in Great Britain. Low levels of relatedness were observed within the beavers currently situated in England. A total of 14% of the beaver pairs examined were shown to be related to some degree but the majority of these were attributed to the translocation of family units. Translocations from Tayside to populations and enclosures in England are currently ongoing. Due to the extreme bottlenecks experienced by Beaver populations across Europe in the preceding centuries, genetic diversity should be maximized by using founders from multiple source populations. A rapid increase in population size will maximize retention of genetic diversity from the released founders. Given the current fragmented distribution of beavers in England, and use of fenced enclosures, this would require ongoing human-mediated movement of individuals between locations. If this is not a feasible strategy, it is likely that most, if not all, populations of beavers in England will require genetic reinforcement via additional translocations. A wider range of samples from free-living beavers in England is needed for a robust assessment of available genetic diversity and to inform downstream management decisions.