Regional-scale assembly rules and biodiversity of coral reefs

Tropical reef fishes and corals exhibit highly predictable patterns of taxo nomic composition across the Indian and Pacific Oceans. Despite steep Longi tudinal and Latitudinal gradients in total species richness, the compositio n of these key taxa is constrained within a remarkably narrow range of valu es. Regional-scale variation in reef biodiversity is best explained by Larg e-scale patterns in the availability of shallow-water habitat. Once habitat area is accounted for, there is surprisingly little residual effect of Lat itude or Longitude. Low-diversity regions are most vulnerable to human impa cts such as global warming, underscoring the urgent need for integrated man agement at multinational scales.