Has the time passed to save endangered wolves in Michigan?
Unfortunately yes, as the world’s longest-running predator-prey study, an attempt to save the nearly wiped-out wolves on Isle Royale through the process of genetic rescue, revealed on April 19.
In March, the National Park Service proclaimed that the natural recovery of the wolves’ population is already “unlikely.” The disappearance of wolves could hold great ecological consequences, as they prey on moose and thus keep the latter from damaging forest vegetation, which is their natural food.
Only two wolves remain on the Lake Superior island while the moose herd of 1,300 is still likely increasing, according to the 58-year report of Michigan Technological University researchers Rolf Peterson and John Vucetich. The two warned that throwing new breeding wolves into the bunch could be a “misunderstanding” of the genetic processes at play.
"The surviving wolves may or may not have any more deleterious genes than you or I, but when combined with a family member's genes, recessive genes can be expressed," says Peterson, reporting that the two remaining wolves are half-siblings – and also a father-daughter pair.
The drop in wolf population on Isle Royale results from inbreeding, with the two remaining wolves definitely family. They will be ages 6 and 8 this spring, while the island wolves’ life expectancy has been around 4 years of age.
Genetic rescue may not be the best idea in this case, as wolves are believed to possess “too many deleterious genes.”
In 2009, for instance, authorities discovered that the local wolf population suffered high rates of malformed backbone, which specifically afflicted one-third of studied specimens. Only one out of 100 wolves suffers the specific condition lumbosacral transitional vertebrae (LSTV) in healthy populations, but on Isle Royale it has steadily increased as inbreeding became more prevalent.
The two scientists, previously staunch supporters of genetic rescue, counted three wolves in the study a year earlier. Now, they did not observe anything to convince them that the wolves could escape extinction and that the moose would not damage the forest due to rapid growth, adds Vucetich.
Geneticist Phil Hendrick from Arizona State University explains that mating between close relatives accelerates inbreeding rates. Offspring produced by the last two wolves in the area, for instance, have an inbreeding coefficient – or measure of severity of their incestuous links – between 0.311 and 0.565.
While inbreeding is also measured in species like Mexican wolves and cheetahs, it is rare for a given population to achieve such high inbreeding coefficients, says Hendrick.
The moose population, on the other hand, is up 4 percent from 2015 – also likely underestimated since administrative limits enabled the scientists to count moose only on three-quarters of the usually covered plots.
Some argue that reintroducing wolves could still limit the ecological damage, while others believe it is best to not intervene anymore.
A public survey by the National Park Service analyzed by Michael Nelson from Oregon State University, however, revealed that 86 percent thought wolves should stay present on Isle Royale even if it means intervening for them. Of the remaining respondents, many opposed intervention out of the belief that healthy ecosystems should be free of human meddling.
