Featured Research

from universities, journals, and other organizations

Tropical Scientists Find Fewer Species Than Expected

Date:
April 25, 2002
Source:
University Of Minnesota
Summary:
An eight-year National Science Foundation-funded study of New Guinean rainforest plants and the insects that feed on them has yielded a new and dramatically lower estimate of the number of species on the planet. The estimate, which lowers the number of species from approximately 31 million to between four and six million, is based on the finding that insects specialize their feeding not on individual species of plants, but on genera and even families of plants.

MINNEAPOLIS / ST. PAUL -- An eight-year National Science Foundation-funded study of New Guinean rainforest plants and the insects that feed on them has yielded a new and dramatically lower estimate of the number of species on the planet. The estimate, which lowers the number of species from approximately 31 million to between four and six million, is based on the finding that insects specialize their feeding not on individual species of plants, but on genera and even families of plants. In "bringing some reality" to estimates of world biodiversity, the study allows scientists to get a better handle on how fast species are being lost, said University of Minnesota plant biologist George Weiblen, the principal plant expert on the research team. The work will be published in the April 25 issue of Nature.

Related Articles


It is important to know how fast biodiversity is being lost, but this is hard to gauge without a solid baseline, Weiblen said. Scientists advising governments on policies to curtail species losses must have credible estimates of species numbers if they are to shape appropriate policies. The stakes are high because losses of too many species or certain kinds of species can cripple tropical forest ecosystems, which normally stabilize soil and climate, purify and recycle water, and produce food, medicine, building materials or other useful products, he said.

The current study took a cross-disciplinary approach; besides Weiblen, the principal scientists were insect expert and project coordinator Scott Miller of the Smithsonian Institution and insect community ecologists Yves Basset of the Smithsonian Tropical Research Institute in Panama and Voytech Novotny of the Czech Academy of Sciences.

The team compared insect communities feeding on 51 tropical plant species, most belonging to either the fig family, the mulberry family or the coffee family. While previous work had also based estimates of total species on numbers of insects--the most species-rich class of animals known--scientists had assumed that each plant-eating insect species tended to feed on one or very few plant species. If true, the estimates of the number of herbivorous insects should be tied to the number of plant species.

"Instead, most insects turn out to be specialized not to plant species, but rather to a genus [grouping of species] or family [grouping of genera] of plants," Weiblen said. "Fewer effective plant 'hosts' means fewer herbivores. Where people had assumed that different insects' food sources overlapped very little, we found that many insects share their food plants with other insect species. There are actually few extreme specialists among tropical insect herbivores."

New Guinea's species diversity made the island an ideal laboratory for the study. Its tropical forests are about the same area as Texas but contain five percent of the world's biodiversity, Weiblen said. The island has 12,000 species of plants; in comparison, Weiblen's home state of Minnesota has only about 1200 species. The work began in 1994 with studies of the insects eating 15 species of figs--Weiblen's area of specialty--that co-occur in the rainforest. The study then expanded to include the mulberry family, which is related to figs, then members of the coffee family and more distantly related plants. The team used DNA sequences to sort out the evolutionary relationships between plants and looked at how insect species were distributed on them.

They found that the tropical forest plant community was dominated by clusters of closely related plant species and that insects tend to feed on multiple close relatives in a given plant genus or family. Because the number of insect species was tied to broader--and therefore less numerous--categories of plants, estimates of their numbers had to be diminished, Weiblen said. Once the estimate of herbivorous insects had been made, the researchers plugged that number into equations to estimate the total number of species in the world. Such equations take into account the proportion of insects that are herbivorous, the proportion of all species that are insects or other members of the arthropod group, the proportion of all plant species that are found in New Guinea, and other factors. Depending on whether insects as a whole follow the pattern of beetles, whose food preferences are quite broad, or moths and butterflies, which are more particular, they estimated that the world contains a total of between about 4.8 million and 6 million species.

"Our estimates bring some reality to predictions about declining biodiversity in the sense that the consequences for insect herbivores of losing a particular host plant species may not be as dire as previously thought," Weiblen said. "But that is no reason to ignore the decreasing number of species worldwide. [Harvard biologist] E.O. Wilson predicted in his book 'The Future of Life' that half of all species will suffer extinction in 50 years if current land use patterns continue. Because the consequences are so severe, we've got to refine our predictions and conserve as many species as possible."


Story Source:

The above story is based on materials provided by University Of Minnesota. Note: Materials may be edited for content and length.


Cite This Page:

University Of Minnesota. "Tropical Scientists Find Fewer Species Than Expected." ScienceDaily. ScienceDaily, 25 April 2002. <www.sciencedaily.com/releases/2002/04/020425072847.htm>.
University Of Minnesota. (2002, April 25). Tropical Scientists Find Fewer Species Than Expected. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2002/04/020425072847.htm
University Of Minnesota. "Tropical Scientists Find Fewer Species Than Expected." ScienceDaily. www.sciencedaily.com/releases/2002/04/020425072847.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Earthworms Provide Cancer-Fighting Bacteria

Earthworms Provide Cancer-Fighting Bacteria

Reuters - Innovations Video Online (Dec. 21, 2014) Polish scientists isolate bacteria from earthworm intestines which they say may be used in antibiotics and cancer treatments. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Existing Chemical Compounds Could Revive Failing Antibiotics, Says Danish Scientist

Existing Chemical Compounds Could Revive Failing Antibiotics, Says Danish Scientist

Reuters - Innovations Video Online (Dec. 21, 2014) A team of scientists led by Danish chemist Jorn Christensen says they have isolated two chemical compounds within an existing antipsychotic medication that could be used to help a range of failing antibiotics work against killer bacterial infections, such as Tuberculosis. Jim Drury went to meet him. Video provided by Reuters
Powered by NewsLook.com
Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Reuters - Light News Video Online (Dec. 19, 2014) Millions of monarch butterflies begin to descend onto Mexico as part of their annual migration south. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins