Climate change-induced wave of hybrid species 'not so much of a problem'

The risk of species interbreeding as a result of climate change shifting their ranges is lower than expected, meaning we are unlikely to see grolar bear-style hybrids emerging across the globe in the near future.

In 2010, an editorial in the journal Nature called the Arctic Melting Pot suggested northern species may start to interbreed, with as many as 34 possible hybridisations between 22 species in the Arctic and near-Arctic.

One of the most prominent species highlighted was the grolar bear or pizzly – a hybrid polar and grizzly bear.

"As more isolated populations and species come into contact, they will mate, hybrids will form and rare species are likely to go extinct," the authors wrote at the time. "As the genomes of species become mixed, adaptive gene combinations will be lost."

However, a study published in the journal Nature Climate Change says this is not necessarily the case, with researchers finding that just 6% of closely related species whose ranges do not overlap at the moment will come into contact by the end of the century.

Lead author Meade Krosby, from the University of Washington's Climate Impacts Group, said: "People have been concerned that climate change would be bringing all these species into contact, and that this could unleash a wave of interbreeding. What we found is, not so much."

Krosby and the team tallied up the potential for hybrid pairings, looking at 9,577 pairs of closely related bird, mammal and amphibian species from North and South America. From the 4,796 pairs where there is currently no overlap of ranges, models show just 6.4% will end up meeting as a result of climate change by 2100.

Researchers also said this is probably an overestimation as it assumes all species will be able to access the new habitats that become available to them, without taking into account man-made barriers like highways and cities.

Most of the overlap is likely to take place among birds in the tropics because more species live in this area and birds have larger ranges. Findings showed an 11.6% overlap for birds, 4.4% for mammals and 3.6% for amphibians.

While little overlap is expected, the authors warned biologists should still pay close attention to wildlife and the future effects of climate change on specific populations: "Managers still need to look case-by-case at species at a local scale, but at a global scale, the big picture is that it's probably not going to be a huge problem," Krosby said.

"The number one strategy for helping biodiversity respond to climate change is to increase connectivity, to link up habitats that have been fragmented by human activity, so species can move, and track climate as it shifts to stay comfortable.

"If people are worried that wildlife corridors and other ways to increase connectivity could bring these species into contact, we're saying: That's probably not going to happen, and allowing species to move is far more important."