With new data appearing in the Nov. 23 issue of the Proceedings of the National Academy of Science, and a $2.6 million grant from the National Science Foundation, an international team of scientists embark on the first worldwide study of the mechanisms driving biodiversity in tropical rainforests.
SAN FRANCISCO, Nov. 18, 1999 - Challenging long-held views that geographic isolation is the singular driver of species diversity in tropical rainforests, a team of researchers from Boston University, San Francisco State University and the University of Queensland report in the Proceedings of the National Academy of Science (PNAS) that natural selection in forest peripheries, or "ecotones," may play an equally important role in the evolution of new species.
The research compliments SFSU team member Thomas B. Smith's groundbreaking work with Robert Wayne (UCLA), et al, published in Science two years ago, which revealed that West African ecotones are hotbeds of evolution, functioning as engines of biodiversity in the region's tropical rainforests. The research presented in PNAS extends the ecotone theory to Australia.
Based on studies of Carlia rubrigularis, a common skink, or lizard, prevalent throughout Australia's wet tropical rainforests and dry open forests, lead author Chris Schneider of Boston University and co-authors Smith, Brenda J. Larison (SFSU) and Craig Moritz (U. of Queensland) found that skink populations living within the ecological gradient, or ecotone, between the two forests exhibited significant differences in their physical appearance compared to their rainforest counterparts, despite evidence of genetic exchange. In striking contrast, rainforest skink populations that have been geographically isolated by a mountain barrier for millions of years were uniformly similar, despite ancient genetic divergence.