The theory of games and microbe ecology

TL;DR

This paper uses game theory to mathematically demonstrate that microbial species with maximum variability in competitive abilities coexist and are resistant to replacement, explaining high intra-species variability and species diversity.

Contribution

It provides a formal proof linking maximum variability in microbes to coexistence and species diversity, a novel theoretical insight.

Findings

Maximally variable microbial species coexist and resist replacement.

Species with less variability are vulnerable to invasion.

Theoretical explanation for high intra-species variability and species richness.

Abstract

Using game theory we provide mathematical proof that if a species of asexually reproducing microbes does not possess maximum variability in competitive abilities amongst its individual organisms, then that species is vulnerable to replacement by competitors. Furthermore, we prove that such maximally variable species are neutral towards each other in competition for limited resources; they coexist. Our proof is constructive: given one species which does not possess maximum variability, we construct a species with the same (or lower) mean competitive ability which can invade, in the sense that its expected value in competition is positive whereas the expected value of the non-maximally variable species is negative. Our results point towards the mechanistic underpinnings for the frequent observations that (1) microbes are characterized by large intra-specific variability and that (2) the number of extant microbe species is very large.