Opposing effects of shared and unshared networks drive species coexistence in intransitive competitive ecosystems

Understanding the mechanisms of species coexistence in intransitive competitive communities, which is generally considered favorable for promoting biodiversity maintenance, has long been a crucial issue in ecology. The role of species dispersal along different pathways in shaping species coexistence and community stability remains highly unexplored. Using a classical metacommunity framework embedding heterogeneous networks, we explore the effects of different dispersal networks hierarchy and species dispersal modes on species coexistence. Species in shared networks fail to achieve stable coexistence, ultimately leading to monoculture dominance. The rate at which extinctions occur accelerates with increasing network heterogeneity. In contrast, in unshared networks, higher heterogeneity promotes species biodiversity, enabling multispecies coexistence. Furthermore, biodiversity patterns under these two dispersal network configurations exhibit diametrically opposed trends. Moreover, increasing ecosystem size generally enhances community stability, though the manifestation of this stability (delayed extinction versus reduced fluctuations) depends on the network configuration. Our findings reveal that maintaining species diversity requires simultaneous consideration of both dispersal network heterogeneity and species dispersal routes.