Molecular and fossil evidence disentangle the biogeographical history of Podocarpus, a key genus in plant geography

PAULA QUIROGA; PAULA MATHIASEN; ARI IGLESIAS; ANDREA PREMOLI; ROBERT MILL

JOURNAL OF BIOGEOGRAPHY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 43 p. 372 - 383

0305-0270

Aim The genus Podocarpus(Podocarpaceae) provides an opportunity to contrast biogeographical hypotheseswithin and among continents. It also offers the chance to analyse divergencebetween disjunct tropical and temperate forests of South America. We developed a calibrated phylogeny of Podocarpusin order to reconstruct ancestral areas and potential expansion routes within Podocarpaceae.Location Podocarpus consists of twoextant subgenera: Foliolatus from Asia and Oceania, and Podocarpuslocated in Gondwanan continents and north to the Caribbean.Methods We combined previously publishedand novel DNA sequences with fossils records. New species sequenced are membersof Podocarpus subgenus Podocarpus from South and Central America. We assembled DNA sequences of thechloroplast (matK and rbcL) and nuclear (ITS1 and ITS2) to analysephylogenetic relationships within Podocarpussubgenus Podocarpus by Bayesianmethods, which were calibrated using macrofossils that could be confidentlyidentified as modern genera. Ancestral areas were inferred using the dispersal?extinction?cladogenesis(DEC) model. Results The phylogenetic reconstructioninferred a minimal origination time for Podocarpuss.l. in the Late Cretaceous?early Palaeogene (65 Ma) and strongly supportedmonophyly of Podocarpus and of subgeneraPodocarpus and Foliolatus. Subgenus Podocarpusconsists of two monophyletic, latitudinally structured clades, one of whichconsists of tropical species sister to a clade including American and Africantaxa.Mainconclusions The history of the subgenera within Podocarpus is older than that previouslyreported: they can be traced back to biogeographical connections betweenAustralasia and South America through Antarctica(Late Cretaceous?early Palaeocene). Latitudinally disjunct lineages within South America most probably diverged from widespreadancestors as a result of a persistent arid barrier that was established priorto the late Palaeogene. The calibrated age for the Tropical?Subtropical cladesuggests an Atlantic?subtropical biogeographical corridor between South Americaand Africa long after the breakup of Gondwanaand the stabilization of the circum-Antarctic current