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giovedì 13 agosto 2015

Mass Extinction Impacts All Species


What species would survive a mass extinction event? Now, scientists have announced that widespread species are at just as high a risk of being wiped out as rare ones after global mass extinction events.


There have been five mass extinction events in the Earth's history, including climate change caused by volcanoes and an asteroid impact. In general, researchers believed that geographically widespread animals were less likely to become extinct than animals with smaller geographic ranges. However, it appears that this may not be true.
In this latest study, the researchers explored the fossil record of terrestrial vertebrates from the Triassic and Jurassic periods, which occurred 252 to 145 million years ago. They found that although geographic ranges do offer insurance against extinction, this insurance disappeared across a mass extinction event that occurred during the Triassic-Jurassic boundary which caused the demise of about 80 percent of the species on the planet at the time.
"The fact that the insurance against extinction given by a wide geographic distribution disappears at a known mass extinction event is an important result," said Alex Dunhill, one of the researchers, in a news release. "Many groups of crocodile-like animals become extinct after the mass extinction event at the end of the Triassic era, despite being really diverse and widespread beforehand. In contrast, the dinosaurs which were comparatively rare and not as widespread pass through the extinction even and go on to dominate terrestrial ecosystems for the next 150 million years."
The findings reveal that when it comes to mass extinctions, it doesn't matter whether a species is widespread or not. These results shed light on the likely outcome of the current biodiversity crisis caused by human activity; it's likely that a human-driven sixth mass extinction will impact all organisms rather than just ones that are endangered.
The findings are published in the journal Nature Communications.
Related Stories

Mass Extinction Impacts All Species: Endangered Animals Aren't the Only Ones at Risk Catherine Griffin Aug 11, 2015 

Earth’s sixth mass extinction event begins with frogs 13 AGOSTO 2015




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