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Since Gleason and Clements, our understanding of community dynamics has been influenced by
theories emphasising either dispersal or niche assembly as central to community structuring.
Determining the relative importance of these processes in structuring real-world communities
remains a challenge. We tracked reef fish community reassembly after a catastrophic coral mortality
in a relatively unfished archipelago. We revisited the stochastic model underlying MacArthur
and Wilson’s Island Biogeography Theory, with a simple extension to account for trophic identity.
Colonisation and extinction rates calculated from decadal presence-absence data based on (1)
species neutrality, (2) trophic identity and (3) site-specificity were used to model post-disturbance
reassembly, and compared with empirical observations. Results indicate that species neutrality
holds within trophic guilds, and trophic identity significantly increases overall model performance.
Strikingly, extinction rates increased clearly with trophic position, indicating that fish communities
may be inherently susceptible to trophic downgrading even without targeted fishing of top