Genetic Mapping Shows Migratory Birds’ Vulnerability to Climate Change

Understanding Evolution Can Help Identify Wildlife Threatened by Climate Change

David Colgan | Jan 4, 2018

 As Earth’s climate changes, species must adapt, shift their ranges or face decline and, in some cases, extinction. Using genetics, biologists involved in the Bird Genoscape Project at UCLA are racing against time to find out the potential for adaptation and how best to protect vulnerable populations of birds.

The project’s most recent study, published today in Science, focuses on the yellow warbler. Ranging across most of North America, the bird winters in Central and South America, and flies as far north as Alaska and the Arctic Circle in the summer, filling wildlands and backyards with color and song along the way.

Using over 200 blood, tissue and feather samples from across the breeding range, the researchers discovered genes that appear to be responding to climate, and found that populations that most need to adapt to climate change are already experiencing declines.

The findings offer valuable information for conservationists who hope to protect species like the yellow warbler in the future, said lead author Rachael Bay, an NSF Biological Collections Postdoctoral Fellow currently studying at UC Davis.

“Evolution has the potential to matter a lot when it comes to climate change response,” Bay said. “It’s a process we should start to integrate more when we make decisions, and it’s shown a lot of promise that hasn’t been realized yet.”

Lead author and UC Davis postdoctoral student Rachael Bay takes measurements of a bird caught in the field. Photo: Daniel Karp/UC Davis

Capacity to adapt

With this research, we can say ‘based on these gene-environment correlations, here’s how populations will have to adapt to future climate change
– Kristen Ruegg

Kristen Ruegg, senior author on the study and co-director of the Bird Genoscape Project, said previous studies focused on how long-term changes in temperature and precipitation cause species to shift their geographic ranges. Genetic mapping offers the opportunity to look at another option — the capacity for adaptation under climate change.

“With this research, we can say ‘based on these gene-environment correlations, here’s how populations will have to adapt to future climate change. And here are the populations that have to adapt most,’” Ruegg said.

Whether the yellow warbler will be able to adapt is another matter. “That’s our next big question,” Ruegg said.

A yellow warbler during breeding season. Genetic analysis indicates that some populations of yellow warblers may have a difficult time adapting to climate change. Photo: Joe Ellis

Some genes mismatched to climate shifts

The study uncovered some of the challenges yellow warblers are already facing. In some populations, genes associated with climate adaptation are already mismatched to environments. These populations will likely have the hardest time adapting quickly enough to future climate shifts.

The yellow warbler is not currently endangered. It was selected for the study to give researchers a better understanding of how genes relate to climate variables across its broad range. But the bird may serve as a canary in the coal mine for other species that are more at risk.

“This is an alarm bell,” said co-author Tom Smith, a professor of ecology and evolutionary biology at UCLA and director of the Center for Tropical Research. “We spend a lot of time asking what is going to happen under climate change, what the effects will be and what we need to do to manage it. Our results shocked us: It’s happening now.”

The study sets the stage for two important next steps, Smith said: conducting additional studies to learn how other species adapt to climate change and informing future conservation management.

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