Positive Interactions in Community Organisation

Abstract

Positive interactions are ubiquitous in ecological communities and can be facultative or obligate mutualisms or commensalisms. Recent decades of work have developed a framework for understanding positive interactions and their role in community structure and function. The stress‐gradient hypothesis was the first conceptual model developed to explain positive interactions and predicted that the frequency of positive interactions increases at physical and biological stress extremes. More recent work has expanded this perspective to habitat‐forming foundation species and the hierarchical organisation of communities. Currently positive interactions are being incorporated into the most utilised models in ecology – niche theory and the Menge–Sutherland Model – expanding the accuracy and predictive value of these models. Simultaneously, the role of positive interactions is being recognised and incorporated into evolutionary theory. Key Concepts Positive interactions are ubiquitous under stressful conditions in communities Mechanistically, positive interactions alleviate physical and biotic stresses Positive interactions are slowly being incorporated into community models Foundation species often provide multiple positive interactions to communities Physical and biotic stresses select for the evolution of mutualisms Evolutionary biology has more proactively incorporated positive interactions into their theoretical framework than community ecology