title: The transition between the niche and neutral regimes in ecology.
abstract: An ongoing debate in ecology concerns the impacts of ecological drift and selection on community assembly. Here, we show that there is a transition in diverse ecological communities between a selection-dominated regime (the niche phase) and a drift-dominated regime (the neutral phase). Simulations and analytic arguments show that the niche phase is favored in communities with large population sizes and relatively constant environments, whereas the neutral phase is favored in communities with small population sizes and fluctuating environments. Our results demonstrate how apparently neutral populations may arise even in communities inhabited by species with varying traits.
authors.affiliation: Department of Physics, Boston University, Boston, MA 02215.
authors.forename: Charles K
authors.initials: CK
authors.lastname: Fisher
authors.affiliation: Department of Physics, Boston University, Boston, MA 02215 pankajm@bu.edu.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Mehta
mesh_terms: D058448:Biota; D017753:Ecosystem; D008954:Models, Biological; D013997:Time Factors
keywords: disordered systems; neutral theory; niche theory; phase transitions