PARENT SESSION
Oral Session #1: Conservation Ecology: Threatened and Endangered Species. Presiding: W. Bond.
Monday, August 6, 2001. 8:00 AM to 12:15 PM. Madison Ballroom C.
A mechanistic model of biodiversity loss.
Pereira, Henrique1, Daily, Gretchen1, 1
ABSTRACT- Most models of biodiversity loss are based on the species-area curve, and thus are phenomenological. In this talk we present a mechanistic model of species extinctions in a community. Using a single species growth-dispersal model (the Skellam model) we determine the conditions for extinction in two cases: 1) a central fragment of high-quality habitat, surrounded by a buffer zone, in turn surrounded by lethal habitat; 2) high-quality habitat repeatedly fragmented by intermediate quality habitat. The conditions for non-extinction can be expressed as the minimum population growth rate that allows a population to survive given the total amount of high-quality habitat. We consider possible distributions of growth rates among the species of a community. For each of these distributions, and for each habitat case, we calculate the relationship between biodiversity and the proportion of remaining high-quality habitat. We show that in a fragmented habitat most biodiversity loss occurs at the earlier stages of fragmentation, but in a non-fragmented habitat most biodiversity loss occurs in the later stages of habitat change or destruction. The distribution of growth rates in a community affects the relationship between biodiversity and the proportion of remaining high-quality habitat.
KEY WORDS: biodiversity, extinction, model, habitat destruction