PARENT SESSION
Contributed Oral Session 6: Biodiversity: Management, Theory, and Techniques
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 516 D, Level 5, Palais des congrès de Montréal

Towards definitive tests of species coexistence mechanisms.

Chesson, Peter^{*,1, 2}, ¹ University of California, Davis, California, USA² University of Arizona, Tucson, Arizona, USA

ABSTRACT- Species coexistence mechanisms have proved difficult to test in natural systems in a convincing way. Recent advances in ecology theory, however, have led to techniques of quantifying the strengths of coexistence mechanisms in terms of the functional components of these mechanisms. For example, the storage effect coexistence mechanism can be quantified in terms of weighted differences of covariances between the responses of organisms to physical environmental factors and competition. This quantification of the storage effect shows that it functions in a system if these covariances change with the densities of the competing species. These results lead to definitive tests for its operation, which can be implemented by employing modifications of standard designs for assessing changes in interaction intensity along an environmental gradient. Other coexistence mechanisms, including classical resource partitioning, can be quantified functionally in a similar way to the storage effect, suggesting experimental designs for definitive tests of these mechanisms also. Of most importance, these tests continue to apply even though multiple coexistence mechanisms may be functioning in a given natural community. Indeed, these tests lead to ways of comparing the relative strengths of the various coexistence mechanisms that may be functioning in a given system.

Key words: species coexistence, storage effect, hypothesis testing, spatio-temporal ecology