Niche and neutral theories correspond to distinct ecological phases
Year: 2013
Type: preprint
Abstract: An ongoing debate in ecology concerns the impacts of ecological drift and selection on community assembly. Ecological drift refers to stochastic changes in species abundance, whereas selection refers to deterministic changes in a population due to fitness differences among species. Niche-based models emphasize the selective role of local interactions between functionally distinct species and their environments for maintaining biodiversity, often ignoring ecological drift entirely. By contrast, neutral models of ecology assume that all species in an ecosystem are functionally equivalent. Consequently, biodiversity in neutral models arises solely from ecological drift due to stochastic population dynamics. We reconcile these two contrasting viewpoints by arguing that the niche and neutral regimes correspond to distinct phases of an ecosystem. Utilizing numerical simulations and analytic arguments from physics based on a mapping between ecological dynamics and the Random Energy Model (REM), we find that the niche phase is favored at high immigration rates and high functional diversity, whereas the neutral phase is favored at low carrying capacities and high stochasticity. Finally, we discuss two examples of ecological patterns or processes -- island biogeography, and the response of a community to a disturbance -- that can be understood as spatial or temporal trajectories through the ecological phase diagram.
Source: arXiv (Cornell University)
Authors: Charles K. Fisher, Pankaj Mehta
Language: English
Subfield: Nature and Landscape Conservation
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W157435760