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March 14, 2005
Contact: Roger Martin, KU Center for Research, (785) 864-7239.

KU researchers' discovery may help predict certain extinctions

LAWRENCE -- A recent discovery by University of Kansas ecologists adds to a growing body of evidence suggesting that findings about life in small ponds or even laboratory beakers are likely to hold true even in the largest bodies of water.

For most organisms, the larger an area of the earth's land or sea surveyed, the more species are found, said Val Smith, professor of ecology and evolutionary biology.

That common-sense observation has been made about birds, mammals or trees. It also has been found true in microscopic water-dwelling animals called zooplankton.

Yet every study, up to the one by Smith and his colleagues, had failed to find the same pattern in phytoplankton, the little plants that zooplankton feast on.

But this week, Smith and his colleagues are reporting that a large survey of water samples, ranging in size from laboratory flasks to oceans, confirms that the more space/more species rule also holds true for these microscopic water plants. The finding, reported online, will appear in the March 22 issue of the Proceedings of the National Academy of Sciences.

Phytoplankton are found in standing water of every kind -- lakes, ponds, reservoirs, oceans. They grow suspended in the water and are the base of the food chain, Smith said.

One reason Smith and his colleagues were surprised to find that phytoplankton follow the same pattern of distribution as larger organisms is that several earlier studies had not confirmed this.

But they found otherwise.

" The scaling of species richness relative to habitat area was remarkably consistent," Smith said, "from a small laboratory flask up to the Arctic Ocean. There is over a hundredfold change in the number of species over that entire habitat-size span."

It's important for a researcher to be confident that he or she can scale up lab findings to the real world, Smith said.

" A skeptic might say, 'I cannot conceive of how a bottle in the lab that holds only as much as a can of beer can tell me anything about Cheney Reservoir.'"

" Now we know that if we find a pattern in the lab, we can have confidence that it reflects a principle of biodiversity that likely applies to natural systems."

The ability to link the number of species to the size of an area has been important in predicting extinctions that follow from reductions in the size of various kinds of habitat.

The studies that came before the one by Smith, KU colleagues Bryan Foster and Frank DeNoyelles, and biologists from the University of Texas and the University of Florida, were based on data collected from a limited number of lakes worldwide.

In contrast, Smith's study sampled 142 natural ponds, lakes and oceans, as well as 239 experimental ecosystems ranging in size from outdoor ponds to laboratory containers about as big around as a Coke can.

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