A phase transition between the niche and neutral regimes in ecology

TL;DR

This paper identifies a sharp phase transition in ecological communities between niche-dominated and neutral-dominated regimes, influenced by population size and environmental stability, revealing how neutral populations can emerge in diverse communities.

Contribution

It demonstrates a phase transition in community assembly regimes and links ecological parameters to the dominance of niche or neutral processes.

Findings

Large populations favor the niche regime.

Small populations favor the neutral regime.

Environmental fluctuations influence regime dominance.

Abstract

An ongoing debate in ecology concerns the impacts of ecological drift and selection on community assembly. Here, we show that there is a sharp phase 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.