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http://www.telegraph.co.uk/science/dinosaurs/8234135/Man-could-create-new-mass-extinction.html
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Man could create new mass extinction
Life on earth is facing a crisis equivalent to mass extinctions such as the demise of the dinosaurs 65 million years ago, scientists have claimed.
Mankind's introduction of invasive species across the globe and destruction of natural habitats threatens to destroy the diversity of species essential to the natural world, researchers claim.
The modern biodiversity crisis, a lack of variation in life forms, means Earth could meet a similar fate to the collapse of marine life 378-375 million years ago – and that of the dinosaurs.
Although Earth has experienced five major mass extinction events, the environmental crash during this Late Devonian event was unlike any other in the planet's history.
The actual number of extinctions was not higher than the natural rate of species loss, but very few new species arose leading to an overall loss of life.
Dr Alycia Stigall, a scientist at Ohio University and author of the paper said: "We refer to the Late Devonian as a mass extinction, but it was actually a biodiversity crisis.
"The main mode of speciation that occurs in the geological record is shut down during the Devonian. It just stops in its tracks."
Lisa Boush, programme director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research, said: "This research significantly contributes to our understanding of species invasions from a deep-time perspective.
"The knowledge is critical to determining the cause and extent of mass extinctions through time, especially the five biggest biodiversity crises in the history of life on Earth.
"It provides and important perspective on our current biodiversity crisis."
The research suggests that the typical method by which new species originate, or vicariance, was absent during this ancient phase of Earth's history and could be to blame for the mass extinction.
Vicariance occurs when a population becomes geographically divided by a natural, long-term event, such as the formation of a mountain range or a new river channel and evolves into a different species.
New species can also originate through dispersal, which occurs when a subset of a population moves to a new location.
Dr Stigall said that human activity has now introduced a high number of invasive species into new ecosystems, making this study relevant for the current biodiversity crisis.
In addition, the modern extinction rate exceeds the rate of ancient extinction events such as the dinosaurs.
Dr Stigall said: "Even if you can stop habitat loss, the fact that we've moved all these invasive species around the planet will take a long time to recover from because the high level of invasions has suppressed the speciation rate substantially."
She suggests that maintaining Earth's ecosystems would be helped by focusing efforts and resources on the protection of a new species generation.
She said: "The more we know about this process, the more we will understand how to best preserve biodiversity."
The research results are published in the journal PLoS One.
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