Building modern coexistence theory from the ground up: The role of community assembly

Abstract

Modern coexistence theory (MCT) is one of the leading methods to understand species coexistence. It uses invasion growth rates—the average, per‐capita growth rate of a rare species—to identify when and why species coexist. Despite significant advances in dissecting coexistence mechanisms when coexistence occurs, MCT relies on a ‘mutual invasibility’ condition designed for two‐species communities but poorly defined for species‐rich communities. Here, we review well‐known issues with this component of MCT and propose a solution based on recent mathematical advances. We propose a clear framework for expanding MCT to species‐rich communities and for understanding invasion resistance as well as coexistence, especially for communities that could not be analysed with MCT so far. Using two data‐driven community models from the literature, we illustrate the utility of our framework and highlight the opportunities for bridging the fields of community assembly and species coexistence.

Higher‐order species interactions cause time‐dependent niche and fitness differences: Experimental evidence in plant‐feeding arthropods

“…Different solutions have been proposed to tackle this challenge, attempting to reduce the complexity of the actual growth model to a Lotka-Volterra model to compute niche and fitness differences (Letten et al, 2017;Singh & Baruah, 2021;Yamamichi et al, 2022). In all these proposed solutions, niche and fitness differences explain why a species can grow from rare, that is, why they have a positive invasion growth rate which ensures coexistence (Spaak & Schreiber, 2023). It, therefore, generally neglects higher-order interactions where both species are abundant.…”

“…Generally, niche and fitness differences are estimated to better understand coexistence and are, therefore, applied to the invasion growth rates (Carroll et al., 2011; Spaak & De Laender, 2020), as positive invasion growth rates of competing species typically imply coexistence (Spaak & Schreiber, 2023; Box 1). Additionally, the sign and magnitude of niche and fitness differences inform about the species interactions, both in quality (e.g.…”