Predicting How Wildlife Will Adapt To Climate Change

Evolutionary biologists typically think about changes that took place in the past, and on the scale of thousands and millions of years. Meanwhile, conservation biologists tend to focus on the needs of present wildlife populations. In a warming world, where more than 10,000 species already face increased risk of extinction, those disciplines leave a crucial gap. We don’t know which animals will be able to adjust, how quickly they can do it, and how people can best support them.

Answers to these questions are often based on crude generalizations rather than solid data. Rachael Bay, an evolutionary biologist at the University of California, Davis, has developed an approach that could help make specific predictions about how at-risk species might evolve over the coming decades. “Injecting evolution into conservation questions is really quite novel,” she says.

The central premise of Bay’s work addresses a common blind spot. Conjectures about how climate change will affect a particular creature often assume that all of them will respond similarly to their changing habitat. In fact, she points out, it’s exactly the variation between individuals that determines if and how a species will be able to survive.

Take the reef-building corals she looked at for her PhD research: Thought to be one of the organisms most vulnerable to extinction as a result of warming oceans, some already live in hotter waters than others. Bay identified genes associated with heat tolerance in the coral Acropora hyacinthus and measured the prevalence of that DNA in populations in cooler waters; from there, she was able to model how natural selection would change the gene pool under various climate-change scenarios. Her findings, published in 2017 in Science Advances, made a splash. The data indicated that the cooler-water corals can, in fact, adapt to warming if global carbon emissions start declining by 2050; if they don’t, or keep accelerating as they have been, the outlook becomes grim.

Bay has continued her work on corals and other marine organisms, but she has also applied her method to terrestrial animals. In 2017, work she conducted with UCLA colleague Kristen Ruegg bolstered the case for keeping a Southwestern subspecies of the willow flycatcher on the US endangered list. Though the species as a whole is abundant, with a breeding range that spans most of the US and southwestern Canada, the subgroup that occupies southern California, Arizona, and New Mexico has struggled with habitat loss. The scientists demonstrated not only that the desert-dwelling birds were genetically distinct enough to merit their own listing, but also that individuals in that population have unique genes that are likely associated with their ability to survive temperatures that regularly top 100°F. Protecting this small subgroup—less than one-tenth of a percent of the total population—could help the entire species persist.

That kind of specific, forward-looking decision is exactly what Bay hopes to enable for other wildlife facing an uncertain future. Other recent work has focused on how yellow warblers, Anna’s hummingbirds, and a coastal Pacific snail called the owl limpet might shift their ranges in response to climate change. “The pie-in-the-sky goal is to make evolutionary predictions that can be used in management,” she says.—M.G.

Publication: Rachael A. Bay, et al., Multilocus Adaptation Associated with Heat Resistance in Reef-Building Corals, Science Direct (2023). DOI: 10.1016/j.cub.2014.10.044

Original Story Source: University of Arizona