Maximal ecological diversity exceeds evolutionary diversity in model ecosystems

Abstract

Understanding community saturation is fundamental to ecological theory. While investigations of the diversity of evolutionary stable states (ESSs) are widespread, the diversity of communities that have yet to reach an evolutionary endpoint is poorly understood. We use Lotka-Volterra dynamics and trait-based competition to compare the diversity of randomly assembled communities to the diversity of the ESS. We show that, with a large enough founding diversity (whether assembled at once or through sequential invasions), the number of long-time surviving species exceeds that of the ESS. However, the excessive founding diversity required to assemble a saturated community increases rapidly with the dimension of phenotype space. Additionally, traits present in communities resulting from random assembly are more clustered in phenotype space compared to random, although still markedly less ordered than the ESS. By combining theories of random assembly and ESSs we bring a new viewpoint to both the saturation and random assembly literature.

An Analytic Solution to The Inhomogeneous Verhulst Equation Using Multiple Expansion Methods

“…However, for more complex cases, numerical studies may be necessary. For instance, the evolution of many species to ecosystem conditions with eutrophication and complex environment [18]- [20] and chaos phenomena [21] serve as an example. Despite its drawbacks, this method provides an in-depth look at the capabilities of logistic equations with their variations as one of the fundamental processes in nature.…”

Diversity loss in microbial ecosystems undergoing gradual environmental changes

“…We expect that there exist both relevant and irrelevant perturbations to our model that could affect the critical scaling we observed. One interesting direction involves considering the distribution of species in phenotype space, which here we take as uniform, but in reality may be quite different (Rubin et al, 2023). We leave a deeper investigation of these questions to future work.…”

“…Alongside competition, microbial communities are defined by their remarkable diversity, supporting the coexistence of thousands of species. How this diversity perseveres, despite the aforementioned competition, remains a central question (Chesson, 2000;Hu, Amor, Barbier, Bunin, & Gore, 2022;Rubin, Ispolatov, & Doebeli, 2023). However, slow yet cumulative environmental changes can provoke a collapse in diversity, leaving ecosystems populated by only a handful of surviving species.…”