Limited dispersal drives clustering and reduces coexistence by the storage effect in a spatially explicit lottery model

Background/Question/Methods

Temporal variation can facilitate coexistence among competitors through the storage effect. However, this theoretical result was derived under the assumption that species have high dispersal rates. Other coexistence mechanisms can be significantly altered by dispersal limitation. Thus, I address whether limited dispersal also impacts coexistence by the storage effect. I incorporate limited dispersal into the classic lottery model, a basic model of interspecific competition that permits coexistence by the storage effect. I develop a set of approximations that highlight different aspects of the spatiotemporal dynamics of competing species with limited dispersal. These approximations help identify elements of spatial pattern driving changes in potential coexistence by the storage effect.

Results/Conclusions

Incorporating limited dispersal into the classic lottery model produces clusters of conspecifics and diminishes potential coexistence by the storage effect. The approximation which most accurately captures the simulated dynamics of the model incorporates the clustering, or nucleation, of individuals when population densities are low. This shows that limited dispersal drives transient clustering in rare species, which in turn dampens the asynchronous fluctuations in reproduction between species that are essential for facilitated coexistence in the storage effect. This result contrasts with previous studies that have identified situations when dispersal limitation and conspecific clustering augment coexistence.