Evolutionary processes underlying latitudinal differences in reef fish biodiversity

Aim: To examine the dynamics among the processes of speciation, extinction and dispersal in marine environments using phylogenies to reveal the evolutionary mechanisms that promote latitudinal differences in biodiversity. Using phylogenetic comparative methods we assess whether tropical reef fish lineages show higher diversification rates and whether the majority of extratropical reef fish lineages have originated from tropical areas. Location: Shallow water tropical and extratropical reefs globally. Methods: Using fossil-calibrated phylogenies for four reef-associated fish families (Chaetodontidae, Labridae, Pomacentridae and Sparidae) we apply evolutionary models (GeoSSE and HiSSE) that allow the estimation of speciation, extinction and dispersal rates associated with geographical ranges and explore potential biases from unsampled characters. Results: We found that tropical lineages show higher rates of speciation and tended to have lower extinction rates. Overall, we identify higher net diversification rates for tropical lineages compared with those in extratropical regions in all four families. Rates of dispersal tended to be higher for lineages with tropical origins expanding into extratropical regions. Within the family Labridae, two tropical lineages were found to exhibit higher net diversification rates, above that expected from latitudinal differences. Main conclusions : Our results offer support for the predictions of the out of the tropics' and evolutionary speed' models of evolution, both of which highlight the marine tropics as an important evolutionary engine promoting latitudinal differences in reef fish biodiversity. Moreover, we find that two tropical labrid lineages are undergoing exceptional diversification associated with additional traits, possibly linked with the extreme sexual dichromatism observed in both clades.

Global Ecology and Biogeography

Global Ecology and Biogeography

25

1466-8238

N/A

12

11