PARENT SESSION
Poster Session 33: Trohpic Structure
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Dynamic cascading extinctions cause greater than expected loss of trophic diversity.
Petchey, Owen*,1, Ebenman, Bo2, Eklöf, Anna2, 1 University of Sheffield, Sheffield, UK2 Linköpings universitet, Linköpings, Sweden
ABSTRACT- One consequence of extinction is secondary extinctions: loss of its only host will make a parasitoid extinct. The complex network of trophic interactions in foodwebs can also result in secondary extinctions, for example by loss of predator mediated coexistence. We investigated how the cascade of secondary extinctions that can result from such mechanisms affects the trophic diversity of model and natural foodwebs. Trophic diversity was the range of trophic strategies employed by the species in the food web and may be an important functional component of biodiversity. Our methods were to simulate extinctions in model foodwebs, identify secondary extinctions using dynamic stability criteria, and compare the resulting foodwebs to foodwebs created by random loss of species. Extinctions obviously reduce trophic diversity, but dynamically determined extinctions caused a much greater reduction (up to 40%) in trophic diversity than extinction determined at random. This occurred regardless of us creating model webs with very different structure and of the specific identity of the initial extinction. Large reductions occurred because species with particular patterns of trophic interaction in the foodweb were more extinction prone. These results add another mechanism by which extinctions of species with particular characteristics cause greater loss of diversity than if species were lost without regard to their biological characteristics. They also encourage caution when interpreting the results of studies that assume random orders of species extinctions.
Key words: Extinction, Diversity, Permanence, Food web