Historical biogeography of herbivorous coral reef fishes: The formation of an Atlantic fauna

Aim To describe the global biogeography of key herbivorous coral reef fish groups since their presumed origins, using data from both fossil and extant species. Location Global Cenozoic reefs. Taxon Acanthuridae (surgeonfishes), Siganidae (rabbitfishes) and Scarini (parrotfishes). Methods We applied the fossilized birth–death model to build chronograms including a comprehensive sampling of extant species and all the fossil occurrences described for each group. With the resulting chronograms, we built biogeographical models considering the geological changes in reef habitat availability since the ancient Tethys Sea. Finally, we used biogeographical stochastic mappings to trace the routes of colonization of the Atlantic Ocean by lineages in our focal taxa. Results We found that the Palaeocene–Eocene was a period of significant lineage origination for surgeonfishes and rabbitfishes in the central Tethys Sea with the appearance of ancient genera. Most of these genera were probably extinct by the Eocene–Oligocene boundary as they do not correspond with modern taxa. Parrotfishes, however, originated in the early Oligocene, an epoch that corresponds with the geographical transition of the marine biodiversity hotspot. In all groups, extant genera had similar origin times and all expanded in the Miocene, mainly in the Indo‐Pacific. In the Atlantic, only one parrotfish lineage with Tethyan ancestry appears to have survived. It subsequently gave rise to extant endemic genera (Sparisoma and Cryptotomus). The other extant lineages in the Atlantic all have Indo‐Pacific origins and colonized more recently using different dispersal pathways. Main conclusions The Indo‐Pacific herbivorous fish fauna is the result of ongoing lineage expansion that started in the central Tethys. The Atlantic is a composite fauna with just one endemic lineage and at least four colonization events from the Indo‐Pacific.