title: Livistona palms in Australia: ancient relics or opportunistic immigrants?
abstract: Eighteen of the 34 species of the fan palm genus Livistona (Arecaceae) are restricted to Australia and southern New Guinea, east of Wallace's Line, an ancient biogeographic boundary between the former supercontinents Laurasia and Gondwana. The remaining species extend from SE Asia to Africa, west of Wallace's Line. Competing hypotheses contend that Livistona is (a) ancient, its current distribution a relict of the supercontinents, or (b) a Miocene immigrant from the north into Australia as it drifted towards Asia. We have tested these hypotheses using Bayesian and penalized likelihood molecular dating based on 4Kb of nuclear and chloroplast DNA sequences with multiple fossil calibration points. Ancestral areas and biomes were reconstructed using parsimony and maximum likelihood. We found strong support for the second hypothesis, that a single Livistona ancestor colonized Australia from the north about 10-17Ma. Spread and diversification of the genus within Australia was likely favoured by a transition from the aseasonal wet to monsoonal biome, to which it could have been preadapted by fire-tolerance.
authors.affiliation: Research School of Biology, Building 44, The Australian National University, Canberra, ACT 0200, Australia. mike.crisp@anu.edu.au
authors.forename: Michael D
authors.initials: MD
authors.lastname: Crisp
authors.forename: Yuji
authors.initials: Y
authors.lastname: Isagi
authors.forename: Yohei
authors.initials: Y
authors.lastname: Kato
authors.forename: Lyn G
authors.initials: LG
authors.lastname: Cook
authors.forename: David M J S
authors.initials: DM
authors.lastname: Bowman
mesh_terms: D028023:Arecaceae / Q000145:classification / Q000235:genetics*; D001315:Australia; D001499:Bayes Theorem; D002467:Cell Nucleus / Q000235:genetics; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017753:Ecosystem; D019143:Evolution, Molecular; D005580:Fossils; D005843:Geography; D006239:Haplotypes; D016013:Likelihood Functions; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant