‘Pivotal’ research could change the wolf debate in the northern Rockies.
By Cory Hatch, Jackson Hole, Wyo.
Date: October 13, 2010
Wolves in the northern Rocky Mountains are genetically healthy and have migrated and bred successfully among subpopulations in central Idaho, greater Yellowstone and northern Montana, according to a new study.
Authors of the study analyzed DNA samples from 555 wolves, beginning with the reintroduction of a few dozen wolves in 1995 and running through 2004, when the population had grown to about 850 animals. The study was published in the October issue of Molecular Ecology.
“We found that genetic diversity was high and maintained throughout the study period for the three recovery areas,” the authors said. “Overall, genetic diversity throughout the [northern Rockies] was comparable or greater than estimates for other gray wolf populations.”
In addition to high levels of genetic diversity, data show “a lack of significant inbreeding in each population,” researchers said. “In addition to a rapid population expansion and a genetically diverse founding population, low inbreeding estimates were probably driven and maintained through behaviorally mediated inbreeding avoidance.”
The study also seems to allay concerns that breeding wolves haven’t been able to migrate among the central Idaho, northern Montana and greater Yellowstone populations.
“The presence of reproductively successful migrants between recovery areas may have influenced genetic diversity,” researchers said. “Idaho and Montana have greater connectivity than either of these areas has to the [greater Yellowstone area].”
The estimate of reproductively successful migrants is low because only about 30 percent of the population was sampled at any given time during the study.
“Our results should be viewed as a conservative minimum of the true number of migrants per generation in the [northern Rockies],” the authors said.
The paper expands on a previous study by some of the same researchers that showed Yellowstone National Park wolves were genetically isolated.
Conservation groups subsequently cited that study as one reason wolves should remain under Endangered Species Act protection, and U.S. District Court Judge Donald Molloy cited genetics in a decision to grant an injunction against wolf hunts after the federal government’s first delisting attempt in 2008.
But the study authors say the 2008 Yellowstone study gave a limited picture of the total population, particularly because most of the park already had established wolf packs.
“High wolf densities and territory saturation in Yellowstone during the height of this study probably limited the ability of individuals to effectively disperse into this core area,” researchers said.
The newer study shows “effective dispersal was most successful outside of Yellowstone during our study, presumably owing to greater opportunities to establish territories and breed.”
The new research is “pivotal,” said study coauthor Mike Jimenez, Wyoming wolf recovery coordinator for the U.S. Fish and Wildlife Service.
“This is a far more in-depth study,” he said, reinforcing the idea that some of early conclusions were a “huge underestimation.” The northern Rocky Mountain wolf population is “very diverse,” he said.
Since the study’s conclusion, the population has doubled to more than 1,700 wolves, which likely increases the level of genetic interchange, Jimenez said.
This genetic diversity shows the 1995 reintroduction was a success biologically.
“It reiterates this idea of three subpopulations and a meta-population,” he said. “It’s worked very well. All three populations are connected to the Canadian population, they’re connected to each other, and they’re connected at much lower [population] levels than we have now.”
What the study doesn’t answer are the political questions surrounding wolves.
“All these arguments come back to people’s values,” Jimenez said. “It doesn’t answer that other question of how many [wolves] people want to have around or don’t want to have around.”
Praise for new study
The study drew praise from other researchers. In a companion article in the same journal, scientists from the University of Calgary and University of Montana said the paper shows “substantial levels of gene flow between three identified sub-populations of wolves within the northern Rockies, clarifying previous analyses and convincingly showing genetic recovery.”
Conservation groups also praised the research, but said state management plans in Wyoming, Montana and Idaho remain a threat to the species.
“I think it’s good research,” Sylvia Fallon, a senior scientist with the Natural Resources Defense Council’s Washington, D.C., office, said in a telephone interview. “It’s good news for the population of wolves in the Rocky Mountains.”
Still, the research doesn’t alleviate the need for a robust population size, Fallon said.
“[The study] occurred between 1995 and 2004, which was soon after reintroduction during a period of time when the population was undergoing tremendous expansion,” she said. “That’s a time when you would expect to see a lot of dispersal.
“What that doesn’t tell us is how dispersal … will be affected by a population that is no longer growing or in fact is decreasing,” Fallon said.
She pointed to remarks by the study authors, who stated a dramatic reduction in population size could threaten connectivity among the populations, and maintaining connectivity will require protection of migration corridors and other prime wolf habitat.
“The success of dispersers will decrease as wolf mortality rates by hunting and control for livestock depredations increase, or if habitat outside of core protected areas becomes less suitable because of land management practices,” researchers said. “Consequently, a management challenge for long-term viability of wolves in the [northern Rocky Mountains] will continue to be the maintenance of adequate population size and effective dispersal to maintain long-term genetic health.”
It’s up to wildlife mangers to ensure this dispersal still occurs, Fallon said.
The new information is a welcome surprise, Louise Lasley, public lands director for the Jackson Hole Conservation Alliance, said. The Conservation Alliance and Natural Resources Defense Council have participated in lawsuits to protect wolves.
“It kind of knocks down one of our arguments,” said Lasley, who is unsure how the new data will affect the litigation. “As far as the Jackson Hole Conservation Alliance, we will still strive to see viable wolf populations that will maintain genetic diversity.”
Lasley echoed Fallon’s concerns about what will happen to connectivity among subpopulations and genetic diversity if wolves are managed to minimal numbers.
State officials said the study confirms their suspicions.
“We never doubted that genetic interchange was occurring at adequate levels among wolves in the greater Yellowstone area,” Steve Ferrell, director of the Wyoming Game and Fish Department, said in a statement. “We had questioned the earlier claims of genetic isolation and bottlenecks in gene flow, especially in light of the robust and rapidly expanding population. We’re pleased that the researchers continued with their work at a larger scale to reverse the conclusions made from their earlier efforts.”
Bob Wharff, Wyoming executive director of Sportsmen for Fish and Wildlife, a group that has advocated for tougher management of the wolf population, said the news is welcome, but said he doubts it will stop lawsuits to protect the species.
“It’s showing what we said all along,” he said. “We believe that wolves have met recovery goals.
“It’s nice for us to finally get a break,” Wharff continued. “But I feel like we’ve had the science on our side all along, and it doesn’t seem to matter.”