Print PageSpecies traits and local environmental conditions often correspond very strongly to one another. However, ecological and evolutionary theory offer separate mechanisms (sorting of species along environmental gradients or adaptation to local environmental conditions) to account for this correspondence. The goal of our analysis was to simultaneously consider how ecological processes, such as extinction and competition, interact with evolutionary processes to structure changes in trait values within a metacommunity.
We modeled the ecological and evolutionary dynamics of an assemblage of primary producers that compete with one another for inorganic nutrients, suffer grazing from primary consumers, and inhabit a spatially and environmentally complex landscape. We used simulations to answer two main questions: (1) does evolution influence metacommunity dynamics? (2) how do the analogous processes of species sorting and local adaptation structure trait change in a metacommunity?
Results/Conclusions
We found that considering evolution of resident species altered patterns observed at the metacommunity level. One species maintained a sink population in another patch. This species evolved fewer and fewer predator defenses in its source patch and sent an increasing number of mal-adapted colonists to the sink patch. Eventually, the better-adapted resident species in the sink patch was driven to extinction, leading to reduced regional species diversity. We also found that both species sorting and local adaptation structure trait change in these evolving metacommunities, and that their relative influence depends on the value of two key parameters: dispersal rate and mutation rate.
Environmental disturbance is a natural feature in many communities. However, human-related activity has increased its occurrence and severity. Many communities respond to environmental disturbances such as acidification, climate change, or eutrophication via shifts in community composition. Clear adaptive shifts in heritable phenotypic traits in response to environmental change have also occurred in other species. Because theories in the fields of evolutionary biology and community ecology developed independently, there are no expectations of when the primary driver of trait composition will be ecological species sorting or evolutionary adaptation. The goal of our model is to determine how ecological and evolutionary processes combine to structure trait changes in communities.
