The Role of Genetics in Polar Bear Conservation

In recent years, scientists have made great progress in decoding the genetic makeup of the world’s polar bears, including how genetically diverse populations are and whether the bears might be able to adapt to a warming Arctic. 

Applying those findings to conservation and management decisions was a natural next step, one that would not only help map out a plan for polar bears but would have implications for other Arctic mammals as well.

A new study by a team of scientists, published in Ecological Monographs, takes on this challenge. We talked with lead author Ruth Rivkin, a Polar Bears International postdoctoral fellow at the University of Manitoba, and one of the coauthors, Geoff York, PBI’s vice president of science and policy, to learn more about the paper and how it could help shape polar bear and Arctic conservation.

How did this study come about and why is it important?

Ruth Rivkin: We know that climate change is a problem for many species. Understanding the evolutionary responses to a warming climate can help us craft strategies to make sure we can conserve as much biodiversity as possible. We used polar bears as an example because they are well-studied and a lot of interesting research has been done recently on polar bear genetics. It seemed timely to take a bird’s eye view of what we’ve learned and how genetic findings can help guide polar bear conservation — an approach that the U.N. is now recommending for all species. And so we brought together a group of biologists who work on polar bear genetics to review and synthesize the last 40 years of research in the field and pull out general trends. We also provided suggestions on what a genetic-focused conservation plan for polar bears could look like and flagged key questions that need to be answered before that can be done. Our goal was to pull information together in a coherent storyline that summarizes what we know, making it more digestible to policy makers. 

Geoff York: Additionally, we highlighted new genetic tools that could revolutionize the way we study and manage polar bears —  for example, using hair traps or biopsy darts to collect genetic samples. Long-term monitoring is critically important to conservation, but it’s been challenging to maintain existing data sets, let alone build out and maintain monitoring in parts of the Arctic that are more remote and difficult to reach. These new and existing genetic tools give us the opportunity to monitor the bears in a way that's scalable and sustainable over time. What’s more, these tools are far less invasive for polar bears, much less expensive, and a lot safer for the people doing the work.

The study is a great example of the value of partnerships and international cooperation. The team involved scientists from the University of Manitoba, Environment and Climate Change Canada, Polar Bears International, the Norwegian Polar Institute, and the San Diego Zoo Wildlife Alliance. We were especially grateful to Evan Richardson of Environment and Climate Change Canada for playing a key role.

Was there a consensus in terms of the polar bears’ ability to adapt to climate change?

Ruth Rivkin: Overall, the studies showed that polar bears are likely not equipped to adapt to climate change. We know that evolutionary change — especially with the amount of genetic diversity in the 20 polar bear populations — is happening across the Arctic. We have well-documented evidence of that. But our review indicates that adaptive changes might not be happening yet and may not be possible for polar bears. What that means is that while there's quite a bit of change in their genetic structure, whether polar bears can actually adapt to warming environments is much less clear. We just don't have the data for that yet, and what data we do have suggests that, genetically, at least, they may not be able to adapt as much as they need to to survive the large amounts of sea ice loss they're experiencing. 

That being said, polar bears live a long time, and they're very smart, and we have a lot of evidence to show that polar bears can change their behaviour to cope with challenging situations. Whether that's enough to help them survive in all parts of the Arctic or in only certain parts of the Arctic, remains less clear. But certainly one of our biggest takeaways is that, evolutionarily and genetically speaking, polar bears may not have the capacity to change enough to match warming conditions. But behaviourally, they are quite flexible, and that's a good thing for the bears.

Can you give us an example of the difference between evolutionary change and adaptive change?

Ruth Rivkin: Sure. Body size is a good example of an evolutionary change that’s probably not adaptive for polar bears. Polar bear body sizes have declined in several populations over the past 30 to 40 years. We don't think the change is adaptive, though, because larger bears produce more cubs and have better survival rates than smaller bears. It’s well-documented in populations where the bears have become smaller that there hasn’t been a corresponding increase in the number of cubs or survival rates. This suggests that while there is an evolutionary response happening, it's not an adaptive response. 

In addition, we know in at least one of those populations, Western Hudson Bay, that there's very little genetic variance, which is an essential component of adaptation. Now, polar bear responses are not equal across the Arctic. There are parts of the Arctic where polar bears are actually doing quite well. Their population numbers are stable. They have good cub survival rates, and cubs are growing into adults. But we don't have data on how those populations are changing physiologically or genetically through time, and so there's this big unanswered question about what’s happening in those populations. 

Earlier, you mentioned behavioural changes that are benefiting some populations. What are some examples?  

Geoff York - As Ruth said, polar bears are very smart and capable of adapting their behaviour — a genetic feature in itself. Polar bears range across a massive area with a great deal of habitat variation. As the Arctic continues to warm, they’re going to respond in different ways in different places, which in the short term is good news. A great example of that is in southeast Greenland, where the polar bears and seals have changed from using sea ice to using freshwater glacial ice. We're seeing that a little bit in Svalbard, too, with a shift in prey, both with the bears hunting different types of seals, but also with hunting Svalbard’s small reindeer on land. Also in Svalbard, some polar bears continue to follow the pack ice as it retreats in summer, but we’re also seeing a small group of bears, about 200-300, that have decided their best strategy is to stick around the island, making the best of what they have, where they are.

Were there any findings in terms of polar bear population boundaries? Could these lead to redrawn maps?

Geoff York: We currently recognize 20 different polar bear populations. But some of the boundaries were drawn more for political and harvest management reasons, especially in areas where we lacked good movement data. But now we have genetic data that is much more robust in terms of defining groups of bears. Canada’s Hudson Bay region is a good example. Genetics can help us determine whether we do, in fact, have multiple populations of polar bears in Hudson Bay (currently defined as Western Hudson Bay, Southern Hudson Bay, and Foxe Basin) and, if so, where the boundaries are. The same holds true for other parts of the Arctic. 

What would a genetics-based management plan look for polar bears? Can you give us an example of what might be included?

Ruth Rivkin: Absolutely. We know that genetic variation is critical to evolution and that gene flow happens through dispersal. So polar bears moving widely across the Arctic can help buffer some of the negative effects of habitat and sea ice loss. A genetics-based management plan would include a focus on maintaining movement corridors — being really careful about where we assign shipping lanes, for example — and preserving as much habitat as we can. Maintaining that connectivity is one of the most clear-cut ways to help preserve polar bears in a warming Arctic. A genetics-based plan would also look at harvest levels from a genetics perspective and use genetic indicators to assess a population’s health. Genetics provide a tangible, measurable way of assessing sustainability and long-term evolutionary potential.

The paper also talks about the importance of including Indigenous knowledge in management plans for polar bears. Can you talk about that?

Ruth Rivkin: Polar bears are an integral part of northern Indigenous cultures. They are essential to a community’s sense of well-being and identity. Working with Indigenous communities to help guide our strategies is something the field has already begun to do and needs to continue doing. As scientists, managers, and conservation planners, we need to make sure that we’re including and recognizing Indigenous knowledge sources and that we’re weaving Western and Indigenous knowledge together to create a more holistic picture of what's happening with the bears. Integrating Traditional Ecological Knowledge with Western knowledge needs to be the focus, not only of research projects going forward, but also of management plans for the polar bears. 

Geoff York: One interesting aspect of genetics research is that we can involve communities in helping to collect genetic data — by setting up hair-snagging stations, for example, along coastlines and collecting the samples. We’ve already started supporting this work in places like James Bay and Foxe Basin, and the findings are helping to inform our understanding of the bears in the Hudson Bay area. Going forward, there’s a tremendous amount of potential for working together to ensure populations have the best possible chance.