Wolf eradication in the US has had a far more devastating impact on the genetic diversity of remaining populations than previously thought, a new study reveals.
Although wolves were systematically eradicated across North America over the last couple of centuries, it had been thought that the human impact on the Canadian wolf population – which is currently a relatively healthy 70,000 – was minor.
Conservationists therefore assumed that the Canadian population had the same level of genetic diversity that had existed in the 19th century – prior to the mass slaughter – and that small-scale re-introductions of these wolves into the US would lead to diversity on a par with this earlier period.
But these assumptions were wrong, according to researchers from the University of Uppsala, Sweden, and the University of California Los Angeles, US, who looked at the genetic diversity of the original wolf populations using DNA analysis. They used bone samples taken from grey wolves dating from 1856 – held in the National Museum for Natural History in Washington DC – and compared this genetic diversity with that of modern wolves.
“We found a 43% drop in genetic variability in the modern wolves,” said Carles Vila, one of the team. “It is impossible for the wolf populations to recover this important diversity, which enables them to adapt to different environmental challenges.”
Bears and lions
Vila notes: “It takes thousands of years of naturally occurring mutations to build up such diversity. And if the Canadian wolves – with such a large population remaining – have lost so much genetic variation, what is the situation for other endangered species in North America, such as bears or mountain lions?”
Wild wolves from across North America were captured and reintroduced to the Yellowstone National Park in Wyoming, US, 10 years ago with considerable success. For example, the population of elk was reduced to more sustainable levels, allowing vegetation to recover.
It was hoped that choosing wolves from across the continent would produce a population with high genetic diversity. But the new research shows this has not happened.
The researchers suggest the wolves’ limited genetic variation will make them more vulnerable to factors such as disease or environmental change, limiting the pack’s ability to survive in adverse conditions.
“The species now exists in such isolated pockets that it is impossible for them to breed across the gaps, so genetic diversity will continue to fall,” Vila told New Scientist.
Read more: http://www.newscientist.com/article/dn6730-wolves-genetic-diversity-worryingly-low.html
In 2007, geneticist, Dr. Ken Fischman, Ph.D, testified at an IDFG open house on Idaho’s then wolf management plan.
Testimony Concerning The Idaho Wolf Population Management Plan – 2008
Idaho Fish & Game Open House
Coeur D’Alene, Idaho, December 12, 2007
Genetic Problems in Small Populations of Idaho Wolves
Ken Fischman, Ph.D.
Sandpoint, Idaho 83864
My name is Ken Fischman, and I live in Sandpoint, Idaho. I have a Ph.D. in Genetics, and over 30 years of experience in Genetic research. I wish to address the question of the number of wolves in Idaho that would constitute a genetically viable population.
Everyone has been impressed by the rapid increase in Wolf numbers since their reintroduction. However, that was to be expected when wolves were first introduced into this area, in which the ecological niches for large carnivores were previously quite open. As these niches are filled, wolf reproduction will likely slow down.
I would like to put the 673 wolves in Idaho in geographical and comparative perspective. The size of Idaho is 82,751 square miles. That works out as one wolf for every 123 square miles. The Human population is more than 1,240,000, which means one wolf for every 1,842 people.
ID F&G has proposed a minimum of 100 wolves and 15 Breeding Pairs as a statewide objective.
A key principal in Population Genetics is that what is important for species preservation is not the total population, but the number of Effective Breeders. ID F&G estimates that there are currently no more than 42 Effective Breeding Pairs in Idaho.(that is, wolves, not people)
Because only a small fraction of a pack reproduces, that further decreases the genetic pool. If Idaho’s wolf numbers are reduced to this level, it could lead to severe inbreeding, thus decreasing their genetic diversity, and making them more prone to a population crash under a variety of circumstances.
The concept that the existence of over ten breeding pairs of wolves should justify removing wolves from the Endangered Species list is therefore biologically insupportable. It is clear therefore, that this was a political, not a scientific decision, and has no basis in any established genetic or evolutionary principles.
Inbreeding is far from the only danger to small populations. Even under the best of circumstances, the lives of wolves are precarious. Any one of dozens of natural or man-made calamities, which could be weathered by large, dispersed populations, such as a virus epidemic, an unusually severe winter, change of climate, or loss of habitat, could wipe out such a small number of animals almost overnight, with permanent loss of their gene pool.
Population Genetics guidelines estimates that a Minimal Viable Population is 500 individuals, and I calculate that the Number of Effective Breeders should be at least 50 pairs.
Under any other circumstances, and with almost any other animal population, the numbers of wolves in ID F&G’s Statewide Objective would be considered, not a success, but a population in danger of extinction.
This is the likely outcome if the number of Idaho’s wolves is reduced to the level ID F&G has proposed.
No, in a manner of speaking, these wolves are not out of the woods yet. A much larger, genetically diverse, and widespread population would be needed if wolves are to become once again a stable, permanent part of the forests of the Northern Rockies.
Thank you for your time and attention.
What happens to a species when genetic diversity declines? Look to the wolves of Isle Royale.
Bone Deformities Linked To Inbreeding In Isle Royale Wolves
ScienceDaily (Apr. 2, 2009) — The wolves on Isle Royale are suffering from genetically deformed bones. Scientists from Michigan Technological University blame the extreme inbreeding of the small, isolated wolf population at the island National Park in northern Lake Superior.
Wolves will never regain the genetic diversity they once had. Instead of conducting more research into wolves decreasing genetic variability, it seems “wolf managers” will just try to guess if the mass slaughter of wolves in the Idaho and Montana hunts will weaken the species even further. Russian Roulette anyone?
Photo: Arctic wolf, Courtesy Wikimedia Commons
Posted in: Wolf Wars, biodiversity
Tags: wolves decreasing genetic diversity, Dr. Ken Fischman, Ph.D, IDFG, University of Uppsala, Sweden, UCLA, wolf inbreeding