Brown bears threatened by isolation, study warns
The brown bears found on the Iberian Peninsula are, for the first time in their evolutionary history, genetically isolated from other European populations19 March 2008
MADRID - The brown bears found on the Iberian Peninsula are, for the first time in their evolutionary history, genetically isolated from other European populations, according to an investigation by Spanish scientists that was published yesterday in the US magazine Proceedings. Moreover, the report concludes that this isolation is relatively recent - having taken place probably no more than a few hundred years ago - and has been caused by human activity.
Such isolation, as well as the reduced size of the bear population - there are only 200 left in the Cantabrian mountains in northern Spain - results in inbreeding, which is a major threat to the species, the researchers say.
Cristina Valdiosera and her colleagues from the Centre for Evolution and Human Behaviour have analysed the DNA of bears in Spain, including some from as far back as 80,000 years ago, as well as 30 or so live subjects.
Strong diversity loss
"We've found remains of old bears with a genetic make-up that reveals their origins in other parts of Europe, including Russia and Eastern Europe," explains Valdiosera. "However, we have detected a strong loss of genetic diversity in recent times."
The investigation is deemed extremely important with regard to defining correct strategies to protect the species, particularly in terms of the controversial measure of bringing in bears from other regions, as has been done in the Pyrenees. The team of scientists warns that although it may seem ideal to preserve the genetic purity of the brown bear, as some would advocate, in practical terms this is in fact a risk.
"Why should we conserve bear populations that are supposedly isolated, and as such, pure, when they have never been in such a situation before?" asks Valdiosera.
The brown bear was once found all over Spain, but has been confined to the Cantabria region for the last 100 years or so. Valdiosera disputes certain theories that claim the species was cut off during certain historical periods, saying that "these bear populations were never completely isolated, not even during the ice age."
The study was carried out by scientists from Spain, France, Germany, the UK and Sweden.
[Copyright El Pais / ALICIA RIVERA 2008]