Researchers Uncover More About European Beaver

The low level of genetic diversity among modern day European beavers, as well as their population distribution, has been strongly tied to human hunting, according to a new study.

An international team, lead by Michi Hofreiter, a professor at the University of York, studied the genetic history of the Eurasian beaver Castor fiber. Researchers found that the European beaver has been drastically impacted by expanding human populations during the last few thousand years.

According to the team, centuries of human hunting accounts for a lack of genetic diversity. Previously, scientists believed changing climate conditions that occurred since the beginning of the Holocene period, which began 11,500 years ago, were to blame. The geographic distribution of the species is also tied to human hunting, according to a press release announcing the findings.

DNA sequencing allowed the team to divide the Eurasian beaver into three distinct groups: those living in western European, eastern European and the Danube basin. The third group existed 6,000 years ago but went extinct during the transition to modern times.

"While beaver populations have been growing rapidly since the late 19th century when conservation efforts began, genetic diversity within modern beaver populations remains considerably reduced to what was present prior to the period of human hunting and habitat reduction," said Hofreiter, from York's Department of Biology and the University of Potsdam's Faculty of Mathematics and Life Sciences.

"In addition, the rapid loss of diversity prior to conservation efforts appears to have established a very strong pattern for the geographic distribution of genetic diversity among present day beaver populations," Hofreiter continued.

Across the northern continents, beavers have been hunted for their valuable and warm fur, as well as their meat and castoreum - an anal gland secretion used in tradition medicine. Evidence suggests beavers have played a major role in human life since around 3,000 to 4,000 years ago.

By the end of the 19th century, only an estimated 1,200 beavers remained.

The research team examined DNA from 48 ancient beaver samples and 152 modern samples in order to determine whether lack of genetic diversity resulted from the near extinction or from factors that occured before human over hunting.

Corresponding author Susanne Horn, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany said: "We found that overall there was more genetic diversity in the past. Apparently, already in ancient times an ancient contact zone existed between the eastern and western populations of beavers in the Oder River area. This is close to a present-day contact zone in Germany and Poland."

"The present-day contact zone was assisted by conservation management and members of the eastern and western population groups meet there today as they did in the past. This suggests that conservation management may, in the long run, help to restore the pre-human impact population structure of threatened species," added Hofrieter.