Global biogeography and diversification of a group of brown seaweeds (Phaeophyceae) driven by clade-specific evolutionary processes

Aim: Historical processes that shaped current diversity patterns of seaweeds remain poorly understood. Using Dictyotales, a globally distributed order of brown seaweeds as a model, we test if historical biogeographical and diversification patterns are comparable across clades. Dictyotales contain some 22 genera, three of which, Dictyota, Lobophora and Padina, are exceptionally diverse. Specifically we test if the evolutionary processes in these clades that shaped their latitudinal diversity patterns are in line with the tropical conservatism, the out-of-the-tropics, and diversification rate hypotheses.

Location: Global coastal benthic marine environments.

Taxon: Dictyotales (Phaeophyceae)

Methods: Species diversity was inferred using DNA-based species delineation, addressing cryptic diversity and circumventing taxonomic problems. A six-gene time-calibrated phylogeny, distribution data of 3,755 specimens, and probabilistic modeling of geographic range evolution was used to infer...