Using modern coexistence theory to understand community disassembly

Abstract Community disassembly examines how species extinction alters ecological communities. Sometimes, the extinction of one species can trigger the loss of others, known as secondary extinction. These secondary extinctions often result from complex species interactions, complicating the identification of underlying mechanisms. Here, we leverage Modern Coexistence Theory to identify when and why secondary extinctions occur. To identify when secondary extinctions occur, we introduce the community disassembly graph, that uses invasion growth rates to identify transitions between coexisting communities due to extinction. When a secondary extinction is identified, we decompose the invasion growth rates associated with the secondary extinction to understand why it occurs. We demonstrate the utility of this framework by applying it to models in which different species interactions–competition, facilitation, and predation–contribute significantly to secondary extinctions. Our results show that Modern Coexistence Theory offers a flexible and interpretable approach to understanding when and why secondary extinctions occur. Competing Interest Statement The authors have declared no competing interest. Footnotes Co-author email: sschreiber{at}ucdavis.edu Statement of Authorship: J. Brennan and S.J. Schreiber conceived the idea. JB performed the computational analyses, created the figures, and drafted the manuscript with feedback from SJS. SJS performed the mathematical analyses with feedback from JB. JB and SJS reviewed and edited manuscript drafts. Data accessibility statement: Code needed to recreate analyses can be found on J. Brennan’s GitHub account at https://github.com/biologyjoe87/MCT_disassembly. No new data was generated in this study. We have updated the methods and discussion of the manuscript. Additionally, we have added more mathematical details into the supplement.