Sept. 22, 2009 -- Sometimes to see something properly, you have to stand farther back. This is true of Chuck Close portraits where a patchwork of many small faces changes into one giant face as you back away.
It may also be true of the frogs of Central America, where the pattern of extinctions emerges clearly only at a certain spatial scale.
Everyone knows that frogs are in trouble and that some species have disappeared, but a recent analysis of Central American frog surveys shows the situation is worse than had been thought.
Under pressure from a fungal disease, the frogs in this biodiversity hot spot are undergoing "a vast homogenization" that is leaving behind impoverished communities that increasingly resemble one another.
"We're witnessing the McDonaldization of the frog communities," says Kevin G. Smith, Ph.D., associate director of the Tyson Research Center at Washington University in St. Louis.
The analysis, of data collected over many years by Karen R. Lips, Ph.D., an associate professor of biology and director of the program in Sustainable Development and Conservation Biology at the University of Maryland and research associate at the Smithsonian Tropical Research Institute, was published online in the October issue of Ecology Letters.
The analysis of frog data was inspired in part by earlier work by Jonathan M. Chase, Ph.D., associate professor of biology in Arts & Sciences, director of the Tyson Research Center and a co-author of the paper.
Chase found that when predatory fish were introduced into artificial ponds at the research center, not only did they reduce diversity within each pond, but they also made the species composition of the ponds more similar.
In the language of ecology, the predators decreased both alpha diversity, or the diversity within each site, and beta diversity, the diversity among sites. The pond study will be published in the November issue
|Contact: Kevin Smith|
Washington University in St. Louis