Heterogeneity of Interaction Strengths and Its Consequences on Ecological Systems

TL;DR

This paper demonstrates through theoretical models that heterogeneity in interaction strengths among species can stabilize ecosystems, promote coexistence, and increase prey populations, challenging traditional assumptions of constant interactions.

Contribution

It introduces a theoretical framework showing how heterogeneity in interaction strengths leads to ecosystem stabilization and higher prey densities, a novel insight into ecological dynamics.

Findings

Heterogeneity allows coexistence of predators and prey where homogeneous models predict exclusion.

Prey populations with heterogeneous interactions reach higher densities than homogeneous counterparts.

Heterogeneity can be a naturally selected feature enhancing ecosystem stability and diversity.

Abstract

Ecosystems are formed by networks of species and their interactions. Traditional models of such interactions assume a constant interaction strength between a given pair of species. However, there is often significant trait variation among individual organisms even within the same species, causing heterogeneity in their interaction strengths with other species. The consequences of such heterogeneous interactions for the ecosystem have not been studied systematically. As a theoretical exploration, we analyze a simple ecosystem with trophic interactions between two predators and a shared prey, which would exhibit competitive exclusion in models with homogeneous interactions. We consider several scenarios where individuals of the prey species differentiate into subpopulations with different interaction strengths. We show that in all these cases, whether the heterogeneity is inherent, reversible, or adaptive, the ecosystem can stabilize at a new equilibrium where all three species coexist. Moreover, the prey population that has heterogeneous interactions with its predators reaches a higher density than it would without heterogeneity, and can even reach a higher density in the presence of two predators than with just one. Our results suggest that heterogeneity may be a naturally selected feature of ecological interactions that have important consequences for the stability and diversity of ecosystems.