Metacommunity connectance and emergent patterns drive diversity via spatial eco‐evolutionary feedback

Self‐organised pattern formation creates heterogeneous growth conditions in spatially extended ecosystems and can support local functional diversity in metacommunities – sets of communities linked by dispersal. However, the mechanisms connecting emergent heterogeneity on the metacommunity scale and diversity on the local scale, and how they depend on metacommunity topology (i.e. size and connectance), remain unclear. To investigate this, we analyse a metacommunity model that incorporates dispersal, trophic interactions, and adaptation within functionally diverse autotroph communities in response to varying local selection pressures. In this model, self‐organised pattern formation emerges as asynchronous, large‐amplitude oscillations in nutrients and biomass densities across patches. These patterns enhance local functional diversity across a wide range of metacommunity sizes and connectance levels. We identify a spatial eco‐evolutionary feedback loop as the key mechanism underlying diversity enhancement by self‐organised pattern formation: emergent patterns strengthen source–sink dynamics and weaken stabilising selection pressures, thereby enabling local communities to adapt to the spatial heterogeneity created by the pattern. This adaptation further reinforces source–sink dynamics, sustaining the feedback. However, in metacommunities with low connectance, pattern amplitudes – and thus the strength of the feedback – are reduced, resulting in lower local diversity. In contrast, different metacommunity sizes modulate local functional diversity levels much less. Our results thus provide a novel mechanistic link between emergent habitat heterogeneity and functional diversity and demonstrate the sensitivity of the underlying feedback to the topology of metacommunities. This highlights the importance of considering the complex joint effects of scale‐dependent (spatial) and eco‐evolutionary feedback on the maintenance of functional diversity in a variety of ecosystems. This is particularly relevant under global land use change, where habitat loss and isolation may disrupt these feedbacks, threatening biodiversity more severely than previously anticipated.