Rapidly evolving species more likely to go extinct, study suggests


Date:
November 10, 2021
Source:
University of Bristol
Summary:
Researchers have found that fast evolution can lead to nowhere.



FULL STORY ========================================================================== Researchers at the University of Bristol have found that fast evolution
can lead to nowhere.


==========================================================================
In a new study of lizards and their relatives, Dr Jorge Herrera-Flores
of Bristol's School of Earth Sciences and colleagues have discovered that
'slow and steady wins the race'.

The team studied lizards, snakes and their relatives, a group called the Lepidosauria. Today there are more than 10,000 species of lepidosaurs,
and much of their recent success is a result of fast evolution in
favourable circumstances. But this was not always the case.

Mr Herrera-Flores explained: "Lepidosaurs originated 250 million years
ago in the early Mesozoic Era, and they split into two major groups,
the squamates on the one hand, leading to modern lizards and snakes,
and the rhynchocephalians on the other, represented today by a single
species, the tuatara of New Zealand. We expected to find slow evolution
in rhynchocephalians, and fast evolution in squamates. But we 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 fast in the Mesozoic, especially those with specialised lifestyles like the marine mosasaurs. But rhynchocephalians
were much more consistently fast- evolving." "In fact, their average
rates of evolution were significantly faster than those for squamates,
about twice the background rate of evolution, and we really did not expect this," said Dr Armin Elsler, another collaborator. "In the later part
of the Mesozoic all the modern groups of lizards and snakes originated
and began to diversify, living side-by-side with the dinosaurs, but
probably not engaging with them ecologically. These early lizards were
feeding on bugs, worms, and plants, but they were mainly quite small."
Prof Mike Benton added: "'After the extinction of the dinosaurs, 66
million years ago, at the end of the Mesozoic, the rhynchocephalians
and squamates suffered a lot, but the squamates bounced back. But for
most of the Mesozoic, the rhynchocephalians were the innovators and the
fast evolvers. They tailed off quite severely well before the end of the Mesozoic, and the whole dynamic changed after that." This work confirms
a challenging proposal made by the famous palaeontologist George Gaylord Simpson in his 1944 book Tempo and Mode in Evolution. He looked at the fundamental patterns of evolution in a framework of Darwinian evolution
and observed that many fast-evolving species belonged to unstable groups,
which were potentially adapting to rapidly changing environments.

Prof Benton continued: "Slow and steady wins the race.In the classic
Aesop's fable, the speedy hare loses the race, whereas the slow-moving
tortoise crosses the finishing line first. Since the days of Darwin,
biologists have debated whether evolution is more like the hare or
the tortoise. Is it the case that big groups of many species are the
result of fast evolution over a short time or slow evolution over
a long time? "In some cases, they can stabilise and survive well,
but in many cases the species go extinct as fast as new ones emerge,
and they can go extinct, just like the napping hare. On the other
hand, Simpson predicted that slowly evolving species might also be
slow to go extinct, and could in the end be successful in the longer
term, just like the slow-moving but persistent tortoise in the fable." ========================================================================== Story Source: Materials provided by University_of_Bristol. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Jorge A. Herrera-Flores, Armin Elsler, Thomas L. Stubbs, Michael J.

Benton. Slow and fast evolutionary rates in the history of
lepidosaurs.

Paleontology, 10 November 2021 DOI: 10.1111/pala.12579 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211110104605.htm

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