The composition of a natural community at any point in time is determined by the historical sequence of past colonizations and the outcomes of interactions between colonists and inhabitants. One important community interaction that can affect community assembly is the priority effect. A priority effect occurs when the first colonizer to a patch gains a numerical advantage such that it can exclude later colonists by monopolizing shared resources. To date, priority effects generally have been understood as purely ecological processes. However, priority effects might also be aided by the local adaptation of recent colonists to new environments through the so-called monopolization effect. In the context of a metacommunity made up of multiple linked evolving populations, dispersal rates and adaptive potential might jointly determine community assembly. Here, we review theories relating to community assembly under varying assumptions about dispersal rate, adaptive potential, and environmental heterogeneity.
Results/Conclusions
We find that dispersal rate and adaptive potential together can shape the assembly and ultimate composition of communities. In general, local adaptation can strengthen priority effects. However, this “metacommunity monopolization effect” depends strongly on adaptive potential, dispersal rate, and environmental heterogeneity. Along a gradient of increasing dispersal rate, a continuum of outcomes are possible, including the classic local monopolization effect, global monopolization where the evolving species monopolizes all patches in the metacommunity, and the species sorting case where adaptation does not affect the matching of species traits to environments. Asymmetries in adaptive potential between species also can lead to a strong advantage for the best adapter. Lastly, the distribution of environments in a metacommunity can strongly influence the pool of species and genotypes available to colonize a new environment, thereby affecting the course of community assembly. These models suggest that community assembly often may be determined by a race between the local adaptation of inhabitants and the time until arrival of better adapted colonists from the regional species pool. The joint consideration of evolution and ecology in a metacommunity offers a promising vantage point from which to understand community assembly.
