( Comfortable living is not why so many d...)Taking evolution's temperature: Researchers pinpoint the energy it takes to make a species

Writing this week in the Proceedings of the National Academy of Sciences, scientists say higher temperatures near the equator speed up the metabolisms of the inhabitants, fueling genetic changes that actually lead to the creation of new species.

The finding - by researchers from the University of Florida, the National Center for Ecological Analysis and Synthesis, Harvard University and the University of New Mexico at Albuquerque - helps explain why more living species seem to exist near the equator, a scientific observation made even before naturalist Charles Darwin set sail to South America on the H.M.S. Beagle nearly two centuries ago.

It may also have a bearing on concepts such as global warming and efforts to preserve diversity of life on Earth.

"We've shown that there is indeed a higher rate of evolutionary change in the form and structure of plankton in the tropics and that it increases exponentially because of temperature," said James Gillooly, Ph.D., an assistant professor of zoology with the UF Genetics Institute. "It tells us something about the fundamental mechanisms that shape biodiversity on the planet."

Speciation - when animals or plants actually evolve into a new species - occurs when life forms with a common ancestor undergo substantial genetic change.

Using a mathematical model based on the body size and temperature-dependence of individual metabolism, the researchers made specific predictions on rates of speciation at the global scale. Then, using fossils and genetic data, they looked at rates of DNA evolution and speciation during a 30-million-year period in foraminifera plankton, a single-celled animal that floats in the ocean.

Researchers compared arrivals of new species of this type of plankton with differences in ocean temperatures at different latitudes ranging from the tropics
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Source:University of Florida