Résumé
Rare species are thought to play a significant role in the delivery of several ecosystem services, in particular resilience to perturbations. However, very little is known on the life history characteristics of these species, especially for coral reef fishes. Here, we characterized diet, size and geographic distribution of rare coral reef fish species of the South Pacific from the analysis of a large data set collected by underwater visual censuses and containing nearly 500 000 fish records along a geographical gradient going from New Caledonia to French Polynesia. Species were considered rare when recorded less than once every 1000 fish records. Results revealed that rare species tended to have smaller geographic distribution than common species. Rare species geographic distribution tended to increase with island isolation and oceanic influence but decreased with island size. Rare species also displayed larger average sizes than common species. Carnivorous and piscivorous species were more frequent amongst rare than amongst common species. The proportion of rare species was not linked to gamma diversity and only weakly correlated to alpha diversity. Large scale factors (island size, island isolation, latitude, and distance to the center of biodiversity) had little influence on the proportion of rare species. These findings suggest that perturbations affecting rare species would affect rare functional groups some of which may be essential to the functioning of reef fish assemblages.