Higuer-order interactions as stabilising mechanism for competitive communities

Abstract

[eng] Ecological communities, like many other complex systems, continue to intrigue researchers to find a way to explain how the biodiversity observed in nature is maintained. This raises a fundamental question: what sustains the stability and the coexistence of species in these ecosystems? Ecological models have largely rested on the premise that species primarily engage in pairwise interactions. Yet, in ecological systems, interactions can often occur in groups of three or more individuals. That is why, in this master’s thesis, we will study a model for competitive community, exploring how higher-order interactions together with different network structures, affect species coexistence and the stability of ecological dynamics. Relying on numerical simulations of the system’s dynamics, we investigate structured communities and non-spatially structured communities, in addition to well-mixed populations, along with some theoretical derivations using a mean-field approximation. Our findings reveal that, network topology and interaction range, together with the presence of higher-order interactions, play pivotal roles in the emergence of coexistence and stability of multi-species competitive communities. For example, we find that for well-mixed populations, when species present the same physiological rates (e.g. birth and death rates), even a small fraction of higher-order interactions are able to stabilise the dynamics. Instead, when physiological rates are different between species, their relative variance dictates the critical fraction of higher-order interactions needed to achieve stable coexistence. These discoveries represent a step forward in our understanding of ecological dynamics and open up promising avenues for future research.