Island Biogeography Theory of coevolution in pollination networks

Island ecosystems have been pivotal in understanding community assembly and biodiversity, from the competing roles of colonization and extinction, to the influence of spatial structure, species interactions, and evolutionary processes. Network theory has helped our understanding of how ecological interactions shape island biogeography dynamics, using empirical and theoretical studies to explore species-rich island community structures. Mutualistic networks on islands differ from those on the mainland by supporting fewer species and more super-generalists, resulting in a more nested community structure. Coevolution, the reciprocal adaptation between interacting species, can shape traits and interactions within these networks, influencing their assembly. Here we explore how colonization, extinction, and coevolution can intersect to shape species traits and the structure of mutualistic networks. Using a stochastic dynamic model, we integrate Island Biogeography Theory with coevolutionary dynamics, examining pollination networks to understand trait-matching in evolving communities. Our results show that highly nested and connected mainland communities contribute to greater instability on islands, particularly under intermediate extinction rates. While super-generalist species persist longer, their persistence does not greatly exceed those species with fewer interactions beyond a threshold, which itself varies with the extinction rate. Additionally, coevolution leads to greater trait-similarity within communities on islands. Our findings highlight the critical role of coevolution in shaping island communities, especially on small islands where the extinction rate is expected to be elevated.