Molecular phylogeny of Cissus L. of Vitaceae (the grape family) and evolution of its pantropical intercontinental disjunctions

Pantropical intercontinental disjunct distribution is a major biogeographic pattern in plants, and has been explained mainly by boreotropical migration via the North Atlantic land bridges (NALB) and transoceanic long-distance dispersal (LDD), and sometimes by vicariance. However, well-resolved phylogenies of pantropical clades are still relatively few. Cissus is the largest genus of the grape family Vitaceae and shows a pantropical intercontinental disjunction with its 300 species distributed in all major tropical regions. This study constructed the phylogenetic relationships and biogeographic diversification history of Cissus, employing five plastid markers (rps16, trnL-F, atpB-rbcL, trnH-psbA and trnC-petN). The results confirmed that Cissus polyphyletic, consisting of three main clades: the core Cissus, the Cissus striata complex, and the Australian–Neotropical disjunct Cissus antarctica – C. trianae clade. The latter two clades need to be removed from Cissus to maintain the monophyly of the genus. The core Cissus is inferred to have originated in Africa and is estimated to have diverged from its relatives in Vitaceae in the late Cretaceous. It diversified in Africa into several main lineages in the late Paleocene to the early Eocene, colonized Asia at least three times in the Miocene, and the Neotropics in the middle Eocene. The NALB seems the most plausible route for the core Cissus migration from Africa to the Neotropics in the middle Eocene. Three African–Asian and two Neotropical–Australian disjunctions in Cissus s.l. are estimated to have originated in the Miocene and may be best explained by LDD.