Ecosystems with mutually exclusive interactions self-organize to a state of high diversity

TL;DR

This paper presents a spatially explicit model showing that mutually exclusive interactions in ecological systems can lead to high species diversity through chain-like invasions and spatial separation, with a phase transition to sustainability.

Contribution

It introduces a novel spatial model for mutually excluding species that explains how high diversity can emerge and be maintained over time.

Findings

Spatial constraints enable coexistence of many species.

Chain-like invasions promote diversity.

A phase transition to high diversity states is identified.

Abstract

Ecological systems comprise an astonishing diversity of species that cooperate or compete with each other forming complex mutual dependencies. The minimum requirements to maintain a large species diversity on long time scales are in general unknown. Using lichen communities as an example, we propose a model for the evolution of mutually excluding organisms that compete for space. We suggest that chain-like or cyclic invasions involving three or more species open for creation of spatially separated sub-populations that subsequently can lead to increased diversity. In contrast to its non-spatial counterpart, our model predicts robust co-existence of a large number of species, in accordance with observations on lichen growth. It is demonstrated that large species diversity can be obtained on evolutionary timescales, provided that interactions between species have spatial constraints. In particular, a phase transition to a sustainable state of high diversity is identified.