A University of Arizona study took a detailed look at the role that temperature plays in evolution and biodiversity. The researchers were surprised at what they found.

The team of scientists set out to examine a long-standing hypothesis that temperature plays a key role in evolution and biodiversity. The presumption was that the tropics have more biodiversity than polar regions because of the warmer temperatures.

But evolutionary biologist Brian Enquist says they found a more nuanced view of that hypothesis.

“And what we found was that, to our big surprise, that instead of temperature, we found that drought and seasonal variation in rainfall, rather than temperature, were actually the most important drivers of variation in biological diversity via measurements of evolutionary diversity,” Enquist said.

The work has implications for climate change modeling, because only a small set of species have the ability to cope with extreme temperatures and drought.