Fast-changing species more likely to go extinct, study finds – ScienceDaily

Researchers at the University of Bristol have found that rapid change cannot lead to anything.

In a new study on lizards and their relatives, Dr Jorge Herrera-Flores of the Bristol School of Earth Sciences and his colleagues have found that “is winning the race slowly and steadily”.

The team studied lizards, snakes and their relatives, a group called lepidosauria. Today there are over 10,000 species of Lepidosaurs, and much of their recent success has been the result of rapid change under favorable circumstances. But this has not always been the case.

Mr. Herrera-Flores explained: “Lepidoosaurs were born 250 million years ago at the start of the Mesozoic era, and they split into two main groups, the squamates on the one hand, leading to lizards and to modern snakes, and rhynchocephali on the other, represented today by a single species, the New Zealand tuatara. We expected to find slow evolution in rhynchocephali, and rapid evolution in squamates. found the opposite.

“We looked at the rate of change in body size among these early reptiles,” said Dr. Tom Stubbs, a collaborator. “We found that some groups of squamates evolved rapidly in the Mesozoic, especially those with specialized lifestyles like marine mosasaurs. But rhynchocephali evolved much faster.”

“In fact, their average evolution rates were significantly faster than those of squamates, about double the background evolution rate, and we really weren’t expecting that,” said Dr. Armin Elsler, another. collaborater. “In the latter part of the Mesozoic, all modern groups of lizards and snakes were born and began to diversify, living side by side with dinosaurs, but probably without engaging with them in an ecological way. fed on insects, worms, and plants, but mostly they were quite small.

Professor Mike Benton added: “‘After the dinosaurs died out 66 million years ago, at the end of the Mesozoic, the rhynchocephali and squamates suffered a lot, but the squamates rebounded. But for the most part of the Mesozoic, the rhynchocephali were the innovators and the rapidly evolving ones, they ran out of steam pretty severely long before the end of the Mesozoic, and the whole dynamic changed after that.

This work confirms a stimulating proposition made by the famous paleontologist George Gaylord Simpson in his 1944 book Changing tempo and mode. He examined the fundamental models of evolution within the framework of Darwinian evolution and observed that many rapidly evolving species belonged to unstable groups, which potentially adapted to rapidly changing environments.

Professor Benton continued, “Slow and steady wins the race. In Aesop’s classic fable, the fast hare loses the race, while the slow turtle crosses the finish line first. Since Darwin’s time, biologists have questioned whether evolution is more like the hare or the tortoise. Is it true that large groups of many species are the result of rapid evolution over a short period or of slow evolution over a long period?

“In some cases, they can stabilize and survive well, but in many cases, species die out as quickly as new ones emerge, and they may die out, just like the napping hare. On the other hand, Simpson predicted that the slow-evolving species might also be slow to become extinct, and might ultimately be successful in the longer term, much like the slow but persistent turtle in the fable. “

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