Document: DOV-3-82-8

Exotic species increase biodiversity of islands.

SAX, D.F.* ¹, J.H.BROWN ² and S.D.GAINES ¹

University of California, Santa Barbara, CA 93106 USA ¹
University of New Mexico, Albuquerque, NM 87131 USA ²

Abstract:
The increase in human population, and the associated consumption of resources and alteration of habitats, is causing the extinction of many species. The resulting decrease in biodiversity at a global scale has also been assumed to occur at local and regional scales. Consequently, much recent ecological research has focused on the effects of reduced local diversity on ecosystem functioning. However, the introduction of exotic species by humans can increase local biodiversity. The net impact of humans on biodiversity is a product of the opposing influences of introductions and extinctions. Island biogeography theory (IBT) provides a framework for examining these processes. As an empirical test of IBT we examined net changes in diversity on islands, whose ecosystems have been altered substantially by humans. Diversity of birds was stable, albeit with modified species composition, whereas diversity of fishes and plants increased substantially. Although island biodiversity has not declined, increases in diversity may pose equally serious threats to ecosystem functioning. Future ecological research needs to examine the impacts of increases in local diversity in the face of declines in global diversity.

Keywords: exotic species, invasion, diversity, biogeography

This abstract is being presented at: 2:00 PM in session:
Oral Session #46: Modeling Populations and Statistical Ecology.