The exploitation of mutualisms

TLDR

Mutualisms are widely exploited by organisms that reap benefits without reciprocation, yet the ecological and evolutionary consequences of such exploitation remain poorly understood, and the phenomenon is heterogeneous, posing potential threats to mutualism stability. The study aims to propose alternative, testable hypotheses for how mutualisms can persist despite exploitation. The author suggests several alternative mechanisms that can be empirically examined to explain mutualism resilience. The author argues that the temptation‑to‑defect framework is inappropriate for most observed forms of exploitation in mutualisms.

Abstract

Mutualisms (interspecific cooperative interactions) are ubiquitously exploited by organisms that obtain the benefits mutualists offer, while delivering no benefits in return. The natural history of these exploiters is well‐described, but relatively little effort has yet been devoted to analysing their ecological or evolutionary significance for mutualism. Exploitation is not a unitary phenomenon, but a set of loosely related phenomena: exploiters may follow mixed strategies or pure strategies at either the species or individual level, may or may not be derived from mutualists, and may or may not inflict significant costs on mutualisms. The evolutionary implications of these different forms of exploitation, especially the threats they pose to the stability of mutualism, have as yet been minimally explored. Studies of this issue are usually framed in terms of a “temptation to defect” that generates a destabilizing conflict of interest between partners. I argue that this idea is in fact rather inappropriate for interpreting most observed forms of exploitation in mutualisms. I suggest several alternative and testable ideas for how mutualism can persist in the face of exploitation.