PARENT SESSION
Oral Session #92: Conservation Ecology: Genetics, population viability, interactions.
Presiding: W. Wirtz
Thursday, August 8. 1:00 PM to 3:45 PM. Grand Ballroom West, Radisson.

Species interactions and population viability analysis .

Sabo, John^*,1, Gerber, Leah¹, ¹ Department of Biology, Tempe, Arizona

ABSTRACT- One of the most commonly used tools for assessing extinction risk is population viability analysis (PVA). PVA's allow practitioners to quantify risk in the face of environmental variability in demographic rates and population abundance. However, one critical assumption of many PVA's is that this variability is attributable entirely to random fluctuations in the environment. This assumption is clearly violated by interactions between focal (threatened) populations and other species (e.g., competitors, predators or disease agents). Species interactions alter the dynamics of threatened species in potentially non-random ways and thus may bias the results of simple PVA's when ignored. We searched the literature for all published studies employing PVA to determine how often these studies included species interactions. Less than 10 % of published PVA studies considered the effects of species interactions in viability assessments for focal populations. Even fewer (< 5%) of these analyses included species interactions explicitly in population models. We use data from simulation models of interacting species to show how a variety of species interactions can bias predictions made from simple extinction risk models. Our results have important ramifications for risk assessment, especially for species threatened by the introductions of exotic competitors, predators or diseases.

KEY WORDS: Population Viability Analysis, Species Interactions, Exotic Species