Study: Rainforest insects are more widespread than previously thought
~ Findings challenge dogma that tropical insect diversity changes dramatically from place to place ~
MINNEAPOLIS / ST. PAUL ( 8/9/2007 ) -- An international team of scientists, including George Weiblen, Bell Museum curator and associate professor at the University of Minnesota, has learned that the same insect species and their food plants are broadly distributed across a vast lowland rainforest on the island of New Guinea. The finding, reported in the Aug. 9 issue of Nature, challenges the dogma that tropical insect diversity changes dramatically from place to place.
"Rainforest explorers have long pondered how the cornucopia of tropical biodiversity is distributed," Weiblen said. "Our study shows that insect species often occupy vast areas of tropical forest such that communities of species don't change much from place to place."
The group studied 500 species of caterpillars, ambrosia beetles and fruit flies across 75,000 square kilometers of contiguous rainforest in Papua New Guinea. Although species diversity was extremely high, as expected in the tropics, communities of insect species did not change much from place to place, even over hundreds of kilometers and complex geological terrain.
Weiblen was lead principle investigator on the National Science Foundation grant that funded the bulk of the study. He played a role in the design and execution of the research and especially in the identification of the New Guinea plants, spending more than a year in the field during the study.
"Our most significant finding is that most lowland rainforest insects in New Guinea are not narrowly distributed eaters of specific plants as previously thought, but are rather widespread eaters of widespread groups of plants," Weiblen said.
The logistics of the study were also noteworthy, Weiblen said.
"We launched eight major expeditions of three months duration to isolated communities each speaking a different language and practicing subsistence agriculture in one of the last, great tropical forest wilderness areas," said Weiblen. "These forests contain countless species that are unknown to science and threatened by human activities. Approximately half of the species in our study are as yet unnamed."
An exciting new direction for the work is the molecular identification of these species or 'DNA barcoding.'
"Some suggest that many named tropical insect species may in fact be complexes of cryptic species with highly specialized diets while others maintain that tropical insects are no less specialized than their temperate cousins. DNA sequencing of New Guinea plants and their insects could settle the debate one way or the other," said Weiblen. "Approximately half of the species in our study are as yet unnamed and few if any are adequately protected."
Weiblen's co-authors include researchers from the Smithsonian Institution, Michigan State University, the Czech Academy of Sciences, the University of Sussex in England, Griffith University in Australia and the Binatang Research Center in Papua New Guinea.
Contacts: George Weiblen, University of Minnesota, (612) 282-8361
Peggy Rinard, College of Biological Sciences, (612) 624-0774
Mark Cassutt, University News Service, (612) 624-8038