June 20, 2013 — The death of individual species shouldn't be the only concern for biologists worried about animal groups, such as frogs or the "big cats," going extinct. A University of California, Berkeley, study has found that a lack of new, emerging species also contributes to extinction.
"Virtually no biologist thinks about the failure to originate as being a major factor in the long term causes of extinction," said Charles Marshall, director of the UC Berkeley Museum of Paleontology and professor of integrative biology, and co-author of the report. "But we found that a decrease in the origin of new species is just as important as increased extinction rate in driving mammals to extinction."
The effects of such a decrease would play out over millions of years, Marshall said, not rapidly, like the global change Earth is experiencing from human activities. Yet, the findings should help biologists understand the pressures on today's flora and fauna and what drove evolution and extinction in the past, he added.
The results, published June 20 in the journal Science Express, come from a study of 19 groups of mammals that either are extinct or, in the case of horses, elephants, rhinos and others, are in decline from a past peak in diversity. All are richly represented in the fossil record and had their origins sometime in the last 66 million years, during the Cenozoic Era.
The study was designed to test a popular evolutionary theory called the Red Queen hypothesis, named after Lewis Carroll's character who, in the book "Through the Looking Glass," described her country as a place where "it takes all the runningyou can do, to keep in the same place."
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