Mating traits can match heat survival traits

New research looks at the impact of rising temperatures on animal reproduction.

Biologists have spent an enormous amount of time trying to understand how animals can survive in the climates they live in for good reason. But how does temperature affect animals beyond survival?

In a paper in the news Ecology LettersMichael Moore, a postdoctoral fellow with the Living Earth Collaborative at Washington University in St. Louis, and his collaborators Noah Leith and Kasey Fowler-Finn at Saint Louis University, examine the state of research on these interactions and propose new ways to study them.

Their new paper considers the many ways thermal biology adapts to the traits favored by sexual selection, including things like courtship, decorative coloration and enlarged weapons like horns or claws.

This image shows examples of how interactions between temperature and sexual selection drive the co-adaptation of thermal physiology, thermoregulation, and sexually selected traits in animals such as lions, elephant seals, antelopes, crickets, Japanese beetles, and rose-bellied lizards. (Credit: Noah Leith and Ecology Letters)

“Now that we’ve studied a huge number of traits that animals have evolved to survive the temperatures they face, we’re starting to realize that these traits also have implications for where and how animals reproduce,” said Moore, whose recent research from research shows. shows that dragonfly males have consistently developed less brood coloration in regions with warmer climates.

“But when we thought about the ways in which an animal’s thermal properties affect how it tries to attract mates, we also couldn’t shake the feeling that this was a very survival-oriented view of the adaptation.

“It hypothesizes that the way animals reproduce in their climate is completely dependent on how they have evolved to survive in that climate,” he says. “However, we know from decades of behavioral ecology research that animals often put themselves at risk of being eaten or parasitized if this means they could potentially attract a mate. We were curious then why the threat of overheating would be any different.”

Mating traits, climate change traits

It turns out that’s not the case: animals will often risk their lives for reproduction, even at the cost of the wrong temperature. Because this risky strategy can sometimes pay off and lead to greater production of offspring in the long run, the researchers found widespread evidence that animals have also evolved mechanisms that allow them to tolerate the dangerous temperatures they encounter only during mating.

And the stakes have never been higher.

“There is an urgent need for biologists and conservationists to understand whether and how organisms are adapting to climate change,” said Leith, lead author of the new study.

“Survival and reproduction are clearly both important for populations to persevere in changing climates, but the adaptations that improve each part of fitness are often more closely linked than we realize,” he says. “Studying the correlated evolution of sexual and thermal traits could change our predictions for which populations are most vulnerable to climate change.”

Future research in this area could also reveal the paths organisms might take as they adapt to a warming world, the scientists say.

If increased heat tolerances have developed in some populations to accommodate the heat absorbed or retained by a trait used for mating, those populations may have advantages that give them an edge in adapting to warming temperatures.

“In some cases, sexual characteristics are even directly beneficial for heat dissipation, such as antelope horns and fiddler’s claws,” says Leith. “Sex selection on horns or claws can therefore work in tandem with natural selection and accelerate adaptation to warmer temperatures. In addition to increasing reproductive success in altered climates, there are several undiscovered ways in which sexual selection can directly improve an organism’s non-mating performance during climate change.

Zoom in on temperature

Fowler-Finn, an associate professor of biology, agrees. Of the many questions and approaches to testing the interplay between thermal ecology and sexual selection raised by this research, she thinks scale is particularly important.

“How thermal microhabitats differ between organisms that vary in size is a super important question that I hope more people tackle,” she says. “Often we generate predictions for the effects of global warming based on air temperatures, which are significantly different from surface temperatures on the ground and vegetation. We won’t really be able to understand the impact of global warming without considering scale.”

The implications of global warming for sexual communication and other reproductive processes are vastly underexposed, Fowler-Finn says. Recent research from her own lab has shown that male locust insects sing at higher frequencies at higher temperatures, and female preferences follow these changes. This phenomenon (called temperature coupling) facilitates the coordination of mating across temperatures.

Looking ahead, Moore says he’s most excited about what he’s learned about how animals have evolved a variety of strategies that allow them to mate at the seemingly wrong temperature.

“What’s really new about our work,” he says, “is that we’re showing that reproduction can sometimes be the primary reason for many of the adaptations animals have to deal with their local climate.”

Source: Washington University in St. Louis

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