Lone wolf brings pack back from the brink
10:24 20 November 02
NewScientist.com news service
Genetic detective work has revealed that a lone interloper from Finland saved
the only pack of Swedish wolves from grave inbreeding and very probable
extinction.
The mysterious male has never been identified, but he left his genetic mark in
the otherwise isolated pack. His arrival added much-needed diversity to its
gene pool and triggered a population explosion.
There are now more than 100 wolves in Sweden in 10 packs – a decade ago there
was a single group with fewer than 10 animals.
Native wolves were thought to have been hunted to extinction in the 1960s. But
in 1983, a single breeding pair was spotted and they had a litter of pups.
Then, according to the genetic evidence, the parents mated with their offspring
and the siblings mated with each other.
They chose inbreeding over not reproducing at all, explains Hans Ellegren of
Uppsala University in Sweden. He is one of the team of scientists that analysed
the genetic profiles of wolves descended from the two original founders, using
DNA samples extracted from hair, blood and faeces.
Date of birth
However, inbreeding had decreased genetic diversity and increased vulnerability
to disease. “Had there been no immigrant, the population would have gone
extinct” Ellegren told New Scientist.
The immigrant had arrived by 1991, as new variants of some genes appeared in
pups born that year. The genetic analysis indicated that the lone wolf had come
from a Finnish population 900 kilometres away.
Moreover, the researchers found that the original founders were also probably
from Finland. This settles an old dispute by squashing rumours that a few
Swedish wolves – which are genetically distinct from their Finnish relatives –
had either been released into the wild by naturalists or somehow survived the
farmers’ guns.
It is currently illegal to hunt wolves in Sweden, except in cases where
individuals have repeatedly attacked livestock. But as the wolf population
grows, so does the tension between the farmers and conservationists.
Journal reference: Proceedings of the Royal Society B (DOI: 10.1098/rspb.2002.2184)