SS2.01 Effects of Biotic Interactions on the Structure and Function of Microbial Food Webs
Date: Wednesday, June 12, 2002
Time: 10:00:00 AM
Location: Saanich
 
BohannanBJ, Dept. of Biological Sciences, Stanford University, Stanford, USA, bohannan@stanford.edu
 
THE IMPACT OF PREDATORS ON THE STRUCTURE OF MICROBIAL COMMUNITIES: THE ROLE OF TRADE-OFFS BETWEEN COMPETITIVE ABILITY AND RESISTANCE TO PREDATION
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A trade-off between competitive ability and resistance to predation has been observed in a number of organisms, and such a trade-off is often assumed in ecological models of food webs. The role of such a trade-off in microbial communities was studied in microbial microcosms and mesocosms. In microcosms, this trade-off allowed the coexistence of different ecological types of bacteria, when predators were present. Genetic factors, environmental factors, and gene by environment interactions determined the magnitude of this trade-off. The magnitude of this trade-off affected in predictable ways the structure and dynamics of these communities, as well as the response of these communities to environmental change. For example, increasing resource input resulted in a shift from dominance by superior resource competitors to dominance by predator-resistant types, as predicted by mathematical models that assume this trade-off. Such models also predict patterns in microbial diversity. For example, a hump-shaped relationship between bacterial diversity and eutrophication is predicted. However, a monotonically increasing, rather than hump-shaped, relationship between bacterial diversity and eutrophication was observed in aquatic mesocosms, contrary to model predictions.