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Tropical rain forest insects have diet similar to temperate insects

Tropical rain forest insects have diet similar to temperate insects

Tropical rain forest insects have diet similar to temperate insects

University of Minnesota
August 23, 2006

A study initiated by University of Minnesota plant biologist George Weiblen has confirmed what biologists since Darwin have suspected – that the vast number of tree species in rain forests accounts for the equally vast number of plant-eating species of insects.

Malaysian beetle. Photo by Rhett A. Butler


Mother nature encourages diversity in rainforest trees.
Older forests have a greater diversity of trees than younger forests according to research published in Friday’s issue of the journal Science. The study — conducted by 33 ecologists from 12 countries — found that nature encourages diversity by selecting for less common trees as the trees mature, indicating that diversity has ecological importance to tropical forests.

Does tropical biodiversity increase during global warming?.
Forest fragmentation may cause biodiversity loss lasting millions of years according to a new study published in the March 31, 2006 issue of the journal Science. Using cores drilled through 5 kilometers of rock in eastern Colombia and western Venezuela, Carlos Jaramillo of the Smithsonian Tropical Research Institute (STRI) in Panama and a team of researchers derived a fossil pollen record for a 72 million-year period with samples ranging from 10 to 82 million years ago. They then correlated pollen diversity with global temperature estimates for the middle part of that sequence (20-65 million years ago) and found that plant diversity seems to increase when tropical forests cover large areas.

Evolution is twice as fast in the tropics.
Tropical species evolve twice as fast as temperate species according to research published in Tuesday’s Proceedings of the National Academy of Sciences (PNAS). The study, which compared the genetics of 45 common tropical plants with similar species from cooler geographical areas, suggests that evolution takes place at a faster rate in warmer climates either due to higher rates of metabolism, which leads to more genetic mutation, or shorter generations, so genetic changes are rapidly passed on to offspring.

Study uncovers how thousands of tree species coexist in rain forest
A group of scientists have a developed a new theory to explain why the biodiversity of tropical rain forests is so high and how species are assembled in an ecological community. According to their research presented in Nature, the answer can be found in “neutral theory” whereby community membership is determined by just five fundamental processes. The scientists say that species will regulate themselves to make room for each other if they follow the “membership rules.” The new theory undermines the conventional “niche theory” which has been traditionally used to explain community assemblages.

“This is a big step forward in the quest to understand why there is so much biodiversity in the tropics,” said Weiblen, principal investigator and senior author for the National Science Foundation-funded research. The study is published in the Aug. 25 issue of the journal Science.

The research showed that insect species in tropical and temperate forests dine on about the same number of tree species, despite the more diverse menu in the tropics.

“The tropical forest cafeteria offers many more options than the temperate forest,” Weiblen said. “Our study confirms that the choices tropical insects make are quite similar to those of insects in less diverse forests of places like Minnesota.”

The study rejected an alternative theory that tropical insects are actually picky eaters who prefer fewer host plants than their temperate counterparts.

“Theory predicts that similar species coexist by dividing up resources like food and space,” Weiblen said. “The unparalleled diversity of plant-eating insects in the tropics could be explained according to this theory if tropical insects were more choosy than those in temperate forests. But it hasn’t been possible to compare what’s on the menu until now.”

Identical experiments on tropical and temperate insects were unknown until Weiblen developed a technique to control for differences in food plant diversity.

“It turns out that insect appetites aren’t all that different near the equator but the tropical smorgasbord brings more species to the table,” Weiblen says.


The study was carried out in Papua New Guinea and the Czech Republic by scientists from the University of South Bohemia, the Smithsonian’s National Museum of Natural History, National Zoological Park, Tropical Research Institute, Comenius University in Slovakia as well as the University of Minnesota.

The researchers, led by Vojtech Novotny of the University of South Bohemia in the Czech Republic, collected insect species feeding on 22 tree species at the Czech and Slovak sites and 22 species in Papua New Guinea. In all, some 850 insect species were recorded.

The study was funded by the U.S. National Science Foundation, the U. S. National Institutes of Health, the Czech Grant Agency, the Czech Academy of Sciences, the Czech Ministry of Education, the National Geographic Society, the Darwin Initiative and the Slovak Grant Agency.

This is a modified news release (“Study: Rain forest insects eat no more tree species than temperate counterparts”) from the University of Minnesota.

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