BALTIMORE, Md. -- Studies of butterfly and ant life on Venezuelan islands newly created by the flooding of the world's second largest reservoir show how dramatically sudden isolation can change even tiny components of a once-integrated ecosystem.
By painstakingly investigating these small invertebrate species for three years, two researchers from Duke University's Nicholas School of the Environment found that inundation has served to exclude some common but highly specialized fruit-eating butterflies from the smallest surviving pieces of the former forest, while at the same time causing leaf cutter ant populations to explode there.
Their studies offer insights into the complex and often unexpected effects of ecological disturbances.
Ghazala Shahabuddin and Madhu Rao prepared reports on their work for presentation at the Ecological Society of America's 1998 Annual Meeting Aug. 3-6.
Their observations and experiments are a part of a larger forest fragmentation study designed by John Terborgh, a professor at the Nicholas School and the department of zoology at Duke. Terborgh, past recipient of a prestigious MacArthur fellowship and an authority on tropical ecosystems, proposed to use the mammoth Lake Guri dam project in east-central Venezuela to simulate what happens to forest habitats that get broken into "islands" by such land-bound activities as agricultural conversion into fields and pastures.
"Generally, it's been found that when chunks of land get separated, dramatic ecological changes take place in the fragments, generally leading to a lot of species extinction at some point," said Shahabuddin, who is one of Terborgh's doctoral students. "I decided to look at butterflies, because very few people look at such invertebrates in forest fragments," she added in an interview.
In 1995, Shahabuddin began to evaluate the ways in which approximately
40 different butterfly species that dine only on rot
Contact: Monte Basgall
Duke University Medical Center