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Evolution puts speed limit on recovery of biodiversity after mass extinctions

By
Brooks Hays
Researchers found the return of species diversity among a group of plankton closely correlated with the general recovery of life in the wake of the K-T extinction event. Photo by Randolph Femmer/U.S. Geological Survey
Researchers found the return of species diversity among a group of plankton closely correlated with the general recovery of life in the wake of the K-T extinction event. Photo by Randolph Femmer/U.S. Geological Survey

April 8 (UPI) -- Life can only recover but so fast in the wake of mass extinctions. According to a new study, evolution imposes a speed limit on the recovery of biodiversity.

Scientists knew it took at least 10 million years for life to recover after mass extinctions, but many researchers assumed environmental factors were responsible for the speed limit.

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The reality of the speed limit is reflected in the fossil record. To better understand why life can only recover so fast, scientists at the University of Texas closely examined how life recovered in the wake of the extinction event that wiped out the dinosaurs.

Some 66 million years ago, an asteroid impact triggered a cataclysmic chain of events, wiping out 75 percent of all species on the planet.

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For the new study, scientists tracked the recovery of foraminifera plankton in millennia after the so-called K-T extinction event. The analysis showed the plankton group regained their physical complexity before their species diversity.

The findings, published this week in the journal Nature Ecology and Evolution, suggest a baseline of ecological complexity -- and corresponding physiological complexity -- must be met before evolution can drive species diversity.

Researchers found the steady increase in foraminifera diversity matched the recovery speed of life in the wake of the K-T extinction event.

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"We see this in our study, but the implication should be that these same processes would be active in all other extinctions," lead author Christopher Lowery, a research associate at the University of Texas Institute for Geophysics, said in a news release. "I think this is the likely explanation for the speed limit of recovery for everything."

Previous studies have shown the environment recovers more quickly than life itself. For some extinction events, the environment recovered and was habitable within a few thousand years after. Yet it took life 10 million years to rebound.

Now scientists know why.

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"Before this study, people could have told you about the basic patterns in diversity and complexity, but they wouldn't have been able to answer which one is leading or how they relate to one another," said Pincelli Hull, an assistant professor at Yale University who did not participate in the study.

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