Surprisingly, inbred isle royale wolves dwindle because of fewer harmful genes

Genomic signatures of extensive inbreeding in Isle Royale wolves, a population on the threshold of extinction

American Association for the Advancement of Science

The tiny, isolated gray wolf population on Isle Royale has withered to near-extinction, but not because each animal carries a large number of harmful genes, according to a new genetic analysis. Instead, each one has been more likely to inherit the same harmful recessive alleles from both parents. This pattern enables expression of related genes as physical deformities, including the population's characteristically crooked spines. The findings contradict many previous studies, which suggest the crux of the genetic problem for historically small or sharply reduced populations is an increase in the quantity of harmful alleles. While the Isle Royale wolf population once consisted of 50 wolves, it has dwindled to just two - a father and daughter that are also half siblings. The collapse of the Isle Royale wolf population occurred despite a reported genetic "rescue" in 1997 by a single migrant from the mainland. To better characterize the genome-wide effects of intense inbreeding and isolation on this population, and their role in its decline, Jacqueline A. Robinson and colleagues analyzed mutations within the protein-coding regions of DNA from Isle Royale wolves, compared with genetic data from wolves in nearby mainland Minnesota. The former didn't have a greater number of deleterious genes than the Minnesota group, but the proportion of Isle Royale wolves with paired harmful recessive alleles in their genome was 38.4% higher. When the researchers compared Isle Royale genetic data with that from other wolf genomes from around the world, they found that individuals from historically large populations more frequently contained two different alleles at a gene location, while those from historically small populations more frequently contained short sequences of identical allele pairings, as with the Isle Royale wolves. These findings, supported by further simulations, contain broader implications for conservation efforts to manage fragmented populations at risk for decline due to inbreeding. Individuals brought in from historically small populations, rather than those from larger, more diverse gene pools, may actually prove more beneficial because they carry fewer potentially harmful alleles.

Wolf-dog 'swarms' threaten Europe's wolves

"Swarms" of wolf-dog crossbreeds could drive Europe's wolves out of existence, according to the lead author of new research.
Such hybridisation - driven by human activities that destroy habitats and mean wolves encounter more and more free-roaming dogs - threatens the "genetic identity" of wolves.
The study compares the views of more than 40 scientists and warns that a lack of engagement and agreement could hamper efforts to tackle wolf-dog hybridisation.
The findings suggest most scientists agree on the nature of the problem, but are divided on how to deal with it.
"We need to address this issue before wolf-dog hybrids backcross with wolves to the extent that wolf populations will be lost to hybrid swarms, and the conservation of wild populations will become unfeasible," said lead author Valerio Donfrancesco, of the Centre for Ecology and Conservation on the University of Exeter's Penryn Campus in Cornwall.
"In this paper, we argue that scientific agreement is crucial to encourage decision-makers to act, and to raise awareness about this conservation issue in society at large.
"The fact that we know so little about the ecology, behaviour and social acceptance of the wolf-dog hybrids adds a layer of concern to the issue."
The study, which allowed scientists to share their views anonymously, revealed agreement that people should be educated about the impact of free-roaming dogs, and that governments should remove wolf-dog hybrids from small and recovering wild wolf populations.
But scientists were divided on issues such as how to remove hybrids and free-roaming dogs, and whether they should be kept captive, sterilised and released or killed.
Donfrancesco said: "The disagreements emerged from diverging ethical values between scientists of different backgrounds, such as ecologists and geneticists, from the lack of data on the effectiveness of different interventions, and from the worry of some scientists that on practical grounds allowing the removal of hybrids would open a legal loophole for the killing of wolves."
Co-author Paolo Ciucci, of the Sapienza University of Rome, said: "The management of hybrids and wolf-dog hybridisation should not be a taboo topic, especially within the scientific community.
"There are margins to develop further consensus among scientists if further research addresses topical issues such as the effectiveness and the feasibility of control measures and their social acceptability.
"Scientists should not avoid the problem just because its management appears overly complex."
Co-author Dr Nibedita Mukherjee, from the University of Exeter, added: "We hope that by highlighting areas of disagreement and why they occur, we will be able to build a more unified scientific opinion, and aid an effective management of this urgent issue."
An estimated 17,000 wolves live in Europe, in populations of varying sizes in countries as far apart as Spain, Greece and Finland.
The paper, published in the journal Frontiers in Ecology and Evolution, is entitled: "Unravelling the scientific debate on how to address wolf-dog hybridization in Europe."

The return of the wolves

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Date:

May 20, 2019

Source:

University of Freiburg

Summary:

Researchers examine global strategies for dealing with predators.

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Howling wolves.

Credit: © dine Haase / Adobe Stock

The current return of wolves to human-dominated landscapes poses a major challenge for the protection of this species, says conservation biologist and private lecturer (PD) Dr. Marco Heurich from the University of Freiburg. He emphasizes that conflicts arise around the conservation of wolves in these landscapes due to farm animal slaughter, competition with hunters and human protection. The question of how humans can coexist with predators triggers a strong emotional debate.

Based on these observations, a team of scientists led by Dr. Dries Kuijper from the Mammal Research Institute of the Polish Academy of Sciences in Białowieża, Poland, analyzed the existing knowledge on how to deal with large carnivores living in the wild in Europe and other parts of the world. The aim was to enable an objective, scientifically sound discussion of various scenarios of wolf management. The researchers have presented their results in the current issue of the scientific journal Biological Conservation.
According to the scientists, the control of wolf populations, which is often advocated in other countries outside the European Union, is in clear contradiction to current European legislation. In addition, several studies show that control of populations by hunting does not resolve conflicts and can even lead to problems between humans and animals. Fencing in the areas where wolves live is a common tool in other parts of the world for the containment of predators. But even that, according to the researchers, is not practicable in the highly fragmented European landscapes to the extent necessary to maintain a healthy wolf population. In addition, large-scale fencing has a negative impact on other wildlife, leading to fragmentation of habitats. However, the scientists claim smaller electric fences are effective in excluding wolves from high-conflict areas with a high density of livestock.
From a legal standpoint, the least problematic situation is when no preventive measures are taken against the wolves, but farm animals are protected and compensation is paid for any damage caused. The team around Heurich assumes, however, that the conflicts between humans and wolves will become more frequent as wolf populations grow. In addition to protecting farm animals with electric fences or guard dogs, for example, the researchers recommend strengthening the natural population of ungulates such as deer and red deer in order to prevent conflicts.
In addition, the scientists suggest influencing wolf behavior and working towards proper human behavior. The use of so-called deterrence measures, i.e. negative conditioning, is intended to ensure that animals avoid humans. At the same time, however, people must learn to have respect for animals. In this way a meeting of wolves with farm animals and humans can be avoided. However, the Freiburg scientists explain that so far the only experience gathered for this method stems from the Yellowstone National Park in the US, so that its suitability for Central Europe must first be investigated.
Finally, Heurich and his colleagues stress that an important aspect of wolf management is to provide the public with a balanced view of the wolves: "People must be convinced of the ecological value that the return of the wolves has. It is necessary to show that these animals pose a very low risk to human safety. However, we must not forget that wolves are large predators who demand respect."

Isle Royale winter study: 13 new wolves, 20 radio-collared moose

IMAGE: Two of the newly introduced gray wolves pick their way through deep snow on Isle Royale. view more 

Credit: Rolf Peterson/Michigan Tech

Fifteen wolves. 2,060 moose. Extensive ice and deep, powdery snow. Michigan Tech researchers have released the annual Winter Study report. In its 61st year, the study is the longest running examination of a predator-prey relationship in the world.
The report chronicles the four-week research expedition to the island, where researchers track -- by ski and plane -- wolves and moose, collar moose, and catalogue the cascading effects of an ecosystem that has lacked a healthy population of apex predators for a number of a years.
New Tracks in the Snow Prior to this fall and winter's wolf reintroductions, the wolf population on the remote island had remained at just two -- a strongly bonded, but also highly inbred male-female pair -- for three years. The moose population, lacking predation, expanded by an average of 19% each year during the past eight years since 2011, when the wolf population first dwindled to fewer than 10 individuals. Consequently, primary plant species in moose diets -- balsam fir and watershield -- dropped precipitously.
The National Park Service (NPS), after an extensive review process, decided to introduce new wolves to the island. In September and October 2018, NPS introduced four Minnesota-born wolves (one male and three females) to the island. In late October, the male wolf died and on January 31, 2019, one of the female wolves left the island by crossing the ice bridge that had formed on Lake Superior, which reached nearly 95% ice cover.
In late February, NPS in collaboration with the Ontario Ministry of Natural Resources (OMNRF), introduced four Canadian-born wolves, including a male and female from a pack near Wawa, Ontario, and two males from Michipicoten Island, Ontario. In late March, NPS and OMNRF introduced seven more wolves to the island, including three males and three females from Michipicoten and one male from near Wawa.
For researchers, perhaps equal parts vexing and exciting are the unanswered questions about the future of the wolves on the island.
"Some of the most important questions at this point are: Will there be pups this year? How quickly will the wolves form a pack, and how many packs?" said John Vucetich, professor of ecology at Michigan Tech and report co-author. "As is so often the case with nature, the answer is, nobody knows -- but three packs is the likely answer."
The Michigan Tech School of Forest Resources and Environmental Science researchers speculated that wolf pups could be possible this year, but the new wolves were introduced to the island near the end of the traditional breeding season, so only time will tell.
Vucetich added that there are similar questions pertaining to the moose. "What's going to happen to the moose population? Will it keep increasing from 2,060, or level off, or decline quickly or slowly? The answer is the same, nobody knows."
To seek the answers, researchers fitted the first GPS-enabled radio collars since 1985 to the newly introduced wolves and 20 moose. The collaring efforts are part of a collaboration with University of Minnesota College of Veterinary Medicine, National Park Service and Grand Portage Band of Lake Superior Chippewa.
New Collars, More Data Collaring the moose will also help researchers understand the effects of predation, as well as other factors that influence the moose population, including forage abundance, parasites and climate.
"As soon as you start collaring individuals you learn about them in great detail; they all have interesting stories," said Rolf Peterson.
The researchers are also excited about their collaboration with Jennifer Forbey, an associate professor of biology at Boise State University, who studies the chemical ecology of herbivory.
Scientists are coming to understand that the reason many herbivores eat what they eat is due to subtle chemical differences in the plants. Isle Royale offers a unique environment in which to study herbivory.
"Most people study a herbivore's decision of what to eat when there are no predators involved," Vucetich said. "They've got all day to figure out which plant they want. But when exposed to a predator, they still have a choice of which plant to eat, but the calculus of the decision is more complex."
And what individual moose elect to eat may have a profound impact on their population as a whole. Lacking predators, the growing moose population has ravaged much of the available forage on the island, and that has consequences.
"We expect there might be a slowing down of moose population growth next year, at least at the west end of the island," said Sarah Hoy, assistant research professor. "The moose have severely damaged much of the vegetation they rely on during winter on the western end of the island. And it was such a deep-snow winter, it'll have been more difficult for them to get around and find food."
According to the report, moose browsing is one factor relating to a decline in the number of mature fir trees. In 1988, 473 mature balsam fir trees were tagged on the western end of the island. Only 28 (6%) of those tagged trees remained in 2018.
Watershield, a floating-leafed aquatic plant, has also experienced decline as the moose population grew. In the late 2000s, watershield covered as much as 90% of the water surface in ponds on the eastern side of the island. By 2018, it was not readily found in aquatic areas.
Next Steps
Reintroducing a thriving wolf population to Isle Royale also has an effect on the island's other residents, which include beavers and foxes. Wolves eat beavers as well as moose, and so the beaver population, which has been booming since 2012, may eventually decline to levels of a decade ago, about 20% of current numbers. Foxes, which are scavengers, will likely benefit from the return of the island's apex predator.
Also of interest to the scientists is evidence of yet additional wolves who may have crossed the ice bridge and visited Isle Royale during the winter. Each winter, the Isle Royale wolf-moose project embeds a husband-wife team, Ky Koitzsch and Lisa Osborn, to observe the moose and wolves by skis, and they found evidence of the tracks of an unknown wolf on the island. Aerial survey suggested that perhaps three wolves crossed the ice and circumnavigated the island, but this may have been just a quick visit followed by a return home to the mainland.
Peterson, Hoy and Vucetich are headed back to the island in May to conduct summer research, along with six students who will showcase their progress on the project's social media.
As usual, four to five dozen volunteers will head to the island for the annual Moosewatch Expedition to collect bones at locations where the collared wolves seem to have lingered long enough to presume they were feeding on a dead moose.
"When we're there in the winter, we learn a tremendous amount about the moose population, but this summer we are hoping to learn a lot more detailed information about moose behavior and what they like to eat, depending on how tolerant the collared moose are of being watched," Peterson said. "This summer should likewise prove valuable in determining the trajectory of both wolf and moose populations. This is definitely a notable year."
Indeed, there is a sense of renewal in this year's report. For the first time in 10 years, the researchers spotted fresh wolf tracks at Windigo.