The riddle: Why are some habitats loaded with many more species than others?

The answer: Nature and evolution respect that there's more than one way of doing things.

"What we've learned," said Michigan State University scientist Charles Ofria, "is that if there isn't just one way to succeed, you'll see diversity."

In an article published in the July 2 issue of Science, an interdisciplinary team of scientists at MSU, the California Institute of Technology and Keck Graduate Institute (KGI), with the help of powerful computers, has used a kind of artificial life, or ALife, to gain insight into questions of evolution.

Up to a point, organisms that are overachievers at what they do to survive consume resources will find there's a ceiling to their good performance. Once they run low on resources, their ability to dominate loses steam and other hard-working organisms have a chance to get a foothold in the habitat.

Ofria, an MSU assistant professor of computer science and engineering and one of the paper's authors, gives the example of an ambitious organism that eats glucose, a type of sugar. That organism is a glucose-eating machine, and the more it eats, the more it reproduces and dominates. But eventually, there are so many hungry organisms, and glucose starts to run out, so the population's growth slows.

Meanwhile, he said, mutant fructose-eating organisms, which maybe aren't quite so vociferous, haven't run out of food. While their greedy neighbors are suffering from glucose famine, they are able to thrive and gain a foothold.

"We show why more than one species can exist in a place," Ofria said."We've found that in a place where resources are finite, there are limiting effects of produc
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Contact: Richard Lenski
lenski@msu.edu
517-355-6463
Michigan State University
1-Jul-2004