(Santa Barbara, Calif.) Biodiversity worldwide may be decreasing, but at smaller scales it is increasing or at least changing in composition, suggesting the need for a dramatic shift in the current focus of ecological research. These changes may undermine the functioning of local ecosystems, according to an article in December's American Naturalist.

The authors Dov F. Sax, assistant research scientist at the University of California, Santa Barbara; Steven D. Gaines, director of the Marine Science Institute and acting vice chancellor for research at UCSB; and James H. Brown, professor of biology at the University of New Mexico studied data collected on oceanic island land birds and plants. Records from islands are useful because they present discrete areas where additions and subtractions of species can be accurately determined.

The article, "Species Invasions Exceed extinctions on Islands Worldwide: A Comparative Study of Plants and Birds," documents the fact that "land birds have experienced massive extinctions on oceanic islands, with many islands losing more than half of their native species," said Gaines. "On these same islands, however, many exotic bird species have become established, such that the total number of land bird species has remained relatively unchanged." (Exotic species are those that are native to one region and have been introduced to another; they can reduce diversity by causing extinctions of native species. However, they also increase diversity by adding to the total number of species in a region.)

Lead author Sax said, "We may be headed for a sort of biotic homogenization, with the same species everywhere. Lose a parrot, get a starling; no one wants that."

Gaines said that while few native plant species have gone extinct, vast numbers of exotic species have become established, according to the island data. As a result, the number of plant species has increased greatly approximately doubling the total number of spe
'"/>

Contact: Gail Gallessich
gail.g@ia.ucsb.edu
805-893-7220
University of California - Santa Barbara
10-Dec-2002

Page: 1 2
Related biology news :

1. Increasing international insect threat to stored food
2. Increasing ozone over the Atlantic ocean
3. Increasing carbon dioxide relieves drought stress in corn, researchers say
4. Increasing nitrogen in Earths soils may signal global changes, say U. of Colorado researchers
5. Increasing carbon dioxide threatens coral reefs
6. Increasing Carbon Dioxide Threatens Tropical Coral Reefs
7. Bacteria Becoming Increasingly Resistant To Antibiotics, But New Vaccines Are On The Horizon
8. Increasing Frequency Of El Nino Takes Toll On Northern Hemispheres Only Penguins
9. Increasing Threat Of Extinction For Amphibians? Scientists To Seek Answers At NSF Workshop
10. The Environmental Consequences Of Increasing Food Production
11. Evidence for the impact of climate change on deep-sea biodiversity