Dynamical mechanism for coexistence of dispersing species

Dispersal of organisms may play an essential role in the coexistence of spe cies. Recent studies of the evolution of dispersal in temporally varying en vironments suggest that clones differing in dispersal rates can coexist ind efinitely. In this work, we explore the mechanism permitting such coexisten ce for a model of dispersal in a patchy environment, where temporal heterog eneity arises from endogenous chaotic dynamics. We show that coexistence ar ises from an extreme type of intermittent behavior, namely the phenomenon k nown as on-off intermittency. In effect, coexistence arises because of an a lternation between synchronized and de-synchronized dynamical behaviors. Ou r analysis of the dynamical mechanism for on-off intermittency lends strong credence to the proposition that chaotic synchronism may be a general feat ure of species coexistence, where competing species differ only in dispersa l rate. (C) 2001 Academic Press.