Complexity can enhance stability in competitive systems

Ian D. Rozdilsky and Lewi Stone The Porter Super-Center for Ecological and Environmental Studies and Department of Zoology, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel. E-mail: [email protected] E-mail: [email protected] Abstract Empirical observations often indicate that complexity enhances stability, while most theoretical studies, such as May's (1972) classic paper, point to the opposite. Despite the wide generality of these latter theoretical analyses, our examination of the well-known competitive Lotka±Volterra system reveals that increasing complexity (measured in terms of connectance) can enhance species coexistence and persistence in model communities (measured in terms of their feasibility and stability). The high feasibility and stability found for tightly interconnected competitive subsystems might provide an explanation for the clumped structure in food webs.