Temperature tolerance has co-evolved with sexual selection

Temperature affects almost every part of an organism’s daily experience. Biologists have already studied at length how animals can survive in the climates in which they live, and the strategies they employ to keep themselves from overheating or freezing to death. However, not much research has been done on how temperature affects animals beyond mere survival. A research team led by the Washington University in St. Louis has now explored the myriad ways in which thermal biology co-adapts with traits favored by sexual selection, including courtship displays, ornamental coloring, or enlarged weapons such as claws or horns.

“Now that we’ve studied a huge number of traits that animals have evolved in order to survive the temperatures they face, we’re starting to realize that these traits also have consequences for where and how animals reproduce,” said study lead author Michael Moore, a postdoctoral fellow in Evolutionary Ecology at the University of Washington. “But as we thought about the ways in which an animal’s thermal traits influence how it tries to attract mates, we also couldn’t shake the feeling that this was a very survival-centric view of the adaptation.”

“It supposes that the ways that animals reproduce in their climate is entirely beholden to how they’ve evolved in order to survive in that climate. However, we know from decades of behavioral ecology research that animals will often put themselves at risk of getting eaten or parasitized if it means they could potentially attract a mate. We were curious then why the threat of overheating should be any different.”

The study revealed that, in fact, animals would often put their lives in danger in order to reproduce, and managed to evolve mechanisms which allow them to tolerate the dangerous temperatures they often encounter during mating. In some animal populations, increased heat tolerance has evolved to accommodate the heat absorbed or retained by traits used for mating, giving them adaptive advantages to warming temperatures – which may turn out to have major benefits in a warming world such as ours.

“In some cases, sexual traits are even directly beneficial for dissipating heat, like antelope horns and fiddler crab claws,” explained study co-author Noah Leith, a doctoral student in thermal ecology and sexual selection at Saint Louis University. “Sexual selection on horns or claws may therefore work in concert with natural selection and accelerate adaptation to warmer temperatures. Beyond increasing reproductive success in altered climates, there are a variety of unexplored ways that sexual selection can directly enhance an organism’s non-mating performance during climate change.”

Further research is needed to clarify the consequences of global warming for sexual interaction and other reproductive processes. “What’s really novel about our work is that we show that reproduction can sometimes actually be the leading reason for many of the adaptations that animals have for dealing with their local climate,” Dr. Moore concluded.

The study is published in the journal Ecology Letters. 

—

By Andrei Ionescu, Earth.com Staff Writer