Document: TIM-3-54-9

Food web structure controls stability of communities with embedded mutualisms.

MCPHEARSON, P.T.* and L.JIANG

Rutger's University, New Brunswick, NJ, 08901, USA ¹

Abstract:
Positive interactions among species are a potentially important, yet relatively poorly researched area of community ecology. For example, attempts to model mutualisms in complex and even simple food webs have been limited. A central question of community ecology concerns the effects of community structure on embedded positive interactions. Are positive interactions destabilizing, and if so, can structural properties of food webs allow for their ubiquitous persistence in nature? We simulated positive species interactions in food webs with multiple configurations ranging from simple to complex structures. The stability of communities with positive pair-wise species interactions was compared with negative pair-wise interactions among all structure types. Stability was assessed by the eigenvalues of the Jacobian matrix. In a few food webs positive interactions stabilized otherwise unstable food webs. Stable food webs were more often destabilized by positive interactions, though in many food webs positive interactions had no effect on stability. Trophic position of the positive interaction had no effect on stability whether the positive interaction was within or between trophic levels. The stability of simple food webs was often affected by positive interaction. Complex food webs, however, were more likely to experience no effect of positive interaction. Given diverse results, food web structure appears to be more important in determining community stability than either sign or trophic position of any mutualistic interaction in the food web.

Keywords: mutualism, positive interaction, community structure, food web, stability.

This abstract is being presented at: 9:15 AM in session:
Oral Session #5: Mutualisms.