Biology subjects

Biroli, G.

Publications and source records attributed to Biroli, G..

2 recordsLinked to original sources

bioRxiv2021

Artificial selection of communities drives the emergence of structured interactions

Species-rich communities, such as the microbiota or microbial ecosystems, provide key functions for human health and climatic resilience. Increasing effort is being dedicated to design experimental protocols for selecting community-level functions of interest. These experiments typically involve selection acting on populations of communities, each of which is composed of multiple species. Numerical simulations explored the evolutionary dynamics of this complex, multi-scale system. However, a comprehensive theoretical understanding of the process of artificial selection of communities is still lacking. Here, we propose a general model for the evolutionary dynamics of communities composed of a large number of interacting species, described by disordered generalized Lotka-Volterra equations. Our analytical and numerical results reveal that selection for total community abundance leads to increased levels of mutualism and interaction diversity. Correspondingly, the interaction matrix acquires a specific structure that is generic for selection of collective functions. Our approach moreover allows to disentangle the role of different control parameters in determining the efficiency of the selection process, and can thus be used as a guidance in optimizing artificial selection protocols.

evolutionary biology↗

bioRxiv2019

Can endogenous fluctuations persist in high-diversity ecosystems?

When can complex ecological interactions drive an entire ecosystem into a persistent non-equilibrium state, where species abundances keep fluctuating without going to extinction? We show that high-diversity spatially-extended systems, in which conditions vary somewhat between spatial locations, can exhibit chaotic dynamics which persist for extremely long times. We develop a theoretical framework, based on dynamical mean-field theory, to quantify the conditions under which these fluctuating states exist, and predict their properties. We uncover parallels with the persistence of externally-perturbed ecosystems, such as the role of perturbation strength, synchrony and correlation time. But uniquely to endogenous fluctuations, these properties arise from the species dynamics themselves, creating feedback loops between perturbation and response. A key result is that the fluctuation amplitude and species diversity are tightly linked, in particular fluctuations enable dramatically more species to coexist than at equilibrium in the very same system. Our findings highlight crucial differences between well-mixed and spatially-extended systems, with implications for experiments and their ability to reproduce natural dynamics. They shed light on the maintenance of biodiversity, and the strength and synchrony of fluctuations observed in natural systems.

ecology↗