title: A long distance dispersal hypothesis for the Pandanaceae and the origins of the Pandanus tectorius complex.
abstract: Pandanaceae (screwpines) is a monocot family composed of c. 750 species widely distributed in the Paleotropics. It has been proposed that the family may have a Gondwanan origin with an extant Paleotropical distribution resulting from the breakup of that supercontinent. However, fossils supporting that hypothesis have been recently reassigned to other families while new fossil discoveries suggest an alternate hypothesis. In the present study, nuclear and chloroplast sequences were used to resolve relationships among Pandanaceae genera. Two well-supported fossils were used to produce a chronogram to infer whether the age of major intra-familial lineages corresponds with the breakup of Gondwana. The Pandanaceae has a Late Cretaceous origin, and genera on former Gondwanan landmasses began to diverge in the Late Eocene, well after many of the southern hemisphere continents became isolated. The results suggest an extant distribution influenced by long-distance-dispersal. The most widespread group within the family, the Pandanus tectorius species complex, originated in Eastern Queensland within the past six million years and has spread to encompass nearly the entire geographic extent of the family from Africa through Polynesia. The spread of that group is likely due to dispersal via hydrochory as well as a combination of traits such as agamospermy, anemophily, and multi-seeded propagules which can facilitate the establishment of new populations in remote locations.
authors.affiliation: University of Hawaii, Botany Department, 3190 Maile Way, Honolulu, HI 96822, USA. Electronic address: tjgallaher@gmail.com.
authors.forename: Timothy
authors.initials: T
authors.lastname: Gallaher
authors.affiliation: Missouri Botanical Garden, P.O. Box 299, St. Louis, MO 63166-0299, USA; Conservatoire et Jardin botaniques de la Ville de Genève, ch. de l'Impératrice 1, case postale 60, 1292 Chambésy, Switzerland.
authors.forename: Martin W
authors.initials: MW
authors.lastname: Callmander
authors.affiliation: Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK.
authors.forename: Sven
authors.initials: S
authors.lastname: Buerki
authors.affiliation: University of Hawaii, Botany Department, 3190 Maile Way, Honolulu, HI 96822, USA.
authors.forename: Sterling C
authors.initials: SC
authors.lastname: Keeley
mesh_terms: D001499:Bayes Theorem; D005075:Biological Evolution; D002467:Cell Nucleus / Q000235:genetics; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D005580:Fossils; D016013:Likelihood Functions; D008957:Models, Genetic; D031673:Pandanaceae / Q000145:classification*; D010802:Phylogeny; D011793:Queensland; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant
keywords: BEAST; Dispersal; Divergence times; Gondwana; Pacific biogeography; RASP