Understanding Asynchrony in Homogeneous Metacommunities
It has become increasingly clear that communities in nature are often not isolated systems, but instead interact with other communities via the movement of organisms (`dispersal'), forming metacommunities. The dynamics of these metacommunities can differ dramatically from what is expected from studying individual communities alone, enabling many new mechanisms for the persistence of species within communities. Central to these mechanisms is asynchrony: differences in the timing or quality of dynamics among communities. Asynchrony is often assumed to arise from environmental differences, however it is also possible for asynchrony to emerge from interactions between identical communities, a phenomenon known as pattern formation.
Here we explore the role of pattern formation in metacommunity dynamics by investigating the mechanisms which lead to asynchrony among identical communities. While it is well known in the literature that the number, magnitude, and distribution of dispersal connections within a metacommunity can influence asynchrony, we demonstrate that measures describing the local stability of the synchronized state can vary independently from these properties of dispersal and plays an important role in the emergence of asynchrony in metacommunities. We also demonstrate that not only the frequency of asynchrony but the types and qualities of asynchronous dynamics vary dramatically between spatial structures with the same amount and distribution of dispersal.
These findings illustrate the importance of understanding the effect of dispersal structure on the dynamical quality of asynchrony, however methods for this are limited. Thus we develop and analyze a simplified model which allows prediction of the asynchronous dynamics possible for a given dispersal structure, and the conditions promoting different dynamical regimes.
Finally, we consider how the structure of interactions between species within communities influence asynchrony. We find that communities which cannot persist in the absence of dispersal among communities are the most prone to asynchrony. The net result is a negative feedback between community persistence in isolation and persistence in the presence of dispersal, confounding predicted relationships between community properties and persistence ability derived from the study of isolated communities alone.