PARENT SESSION
Organized Oral Session 53: Days to decades and meters to miles: Exploring community dynamics across scales, taxa, and habitats
Organizer(s): JE Houlahan and CScott Findlay
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 510b, Level 5, Palais des congrès de Montréal
A test of the 'neutral model' assumption of stochastic zero-sum communities.
Woiwod, Ian*,1, Currie, David2, Fuhlendorf , Sam3, Gaedke , Ursula4, Houlahan, Jeff5, Willis, Theo6, 1 Rothamsted Research, Harpenden, Hertfordshire, UK2 University of Ottawa, Ottawa, Canada3 Oklahoma State University, Stillwater4 University of Potsdam, Potsdam, Germany5 University of New Brunswick, Saint John, Canada6 University of Toronto, Toronto, Canada
ABSTRACT- Ecology is the study of the distribution and abundance of organisms and recently Hubbell has presented a theoretical framework, 'neutral models', for explaining large-scale patterns of community structure. These models have been remarkably effective at explaining large-scale patterns of diversity and relative species abundances, but good model fit alone does not prove that a model is 'true'. Neutral model theory makes a fundamental and testable assumption that the total abundance of organisms in ecological communities stays constant over time. In fact, Hubbell writes that neutral model theory "rests on a key first principle, namely that the interspecific dynamics of ecological communities are a stochastic zero-sum game". Implicit in this assumption is that density dependence is a powerful driver of community structure but that it operates at the community level. An important prediction that follows from this first principle is that on average across the entire community there should be strong negative covariance because, in a zero-sum game, if an individual of one species dies another individual from the same or another species must replace it. Thus, if one species declines in abundance by a specified number of individuals another or several others must increase in abundance by that same number of individuals. This simple prediction can be used to test whether the dynamics of natural communities are consistent with the zero-sum assumption of the neutral model. We have collected data for 15 natural communities from many different taxa, habitats and scales and used these datasets to test whether the zero-sum assumption is met in natural communities.
Key words: Hubbell