"The differences in the shape, size and sexual maturity of skinks between the rainforest and adjacent open forest populations, but not between historically isolated populations, suggests that natural selection rather than isolation is promoting these physical differences," says Schneider. "This stands in stark contrast to the prevailing view that geographic isolation alone is the key to population divergence and speciation."

"The skink work strengthens our ideas that this is not just something happening in a few bird species in Cameroon. It's happening in another rainforest, with different taxa," says Smith.

Because preserving the processes that maintain diversity in rainforests is fundamental to effective conservation, the researchers are launching a comprehensive investigation of the mechanisms responsible for generating biodiversity in the world's tropical rainforests. With a $2.6 million grant from the National Science Foundation (NSF), Smith will lead an international team of scientists, students and policy makers on a three-continent study to test alternative hypothesis of speciation, with the goal of defining better conservation policy. Collaborating institutions include NASA, the World Resources Institute, Boston University, UCLA and the University of Queensland.

"The general belief is that if we preserve rainforests, we're also preserving the processes that create biodiversity. But considering the role of ecotones, that may not be the case," says Smith, an evolutionary biologist and director of SFSU's Center for Tropical Research (CTR), which received the NSF grant.

In a 1997 Science article, veteran evolutionary biologist John Endler hailed the ecotone work as a "major first step" in supporting the hypothesis that natural selection not only shapes the physical appearance of all li
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Contact: Merrik Bush-Pirkle
merrik@sfsu.edu
415-338-6747
San Francisco State University
21-Nov-1999