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Abstract Detail


Biogeography

Chung, Kuo-fang [1], Peng, Ching-I [1], Schaal, Barbara [2].

Tracking the origin and dispersal of the South Pacific Alpine Plants: Phylogenetics and Phylogeography of Oreomyrrhis clade of Chaerophyllum (Apiaceae).

Vicariance hypotheses, long dominant in South Pacific phytogeography, have gradually given way to transoceanic long-distance dispersal (LDD) hypotheses as molecular systematic studies repeatedly yield phylogenies and age estimates inconsistent with the sequential breakup of Gondwana. This paradigm shift implies a younger and more complicated history for the South Pacific flora. To understand how LDD has shaped the biodiversity of this region, larger datasets comprising well-resolved phylogenies from diverse lineages are needed. In this study, we use phylogenetic and phylogeographic approaches to infer the origin and pattern of dispersal in Oreomyrrhis clade of Chaerophyllum, a young lineage of Pliocene-Pleistocene origin found in alpine and subalpine habitats on continents and continental islands around the South Pacific Basin. Phylogenetic analyses of the combined dataset (nuclear ITS and chloroplast trnS-trnG and atpB-rbcL sequences) reveal two clades lacking internal resolution: a clade composed of New Guinean and Bornean species and another clade comprising all other species. Star-like haplotype networks and significant negative values of Tajima's D test for all three datasets imply a biogeographic scenario dominated by range expansion. In all three haplotype networks, only the most ancestral haplotypes are found in more than one area, suggesting that dispersals from the center of origin had happened prior to the origination of more derived haplotypes. Assuming that the center of origin is the region harboring the ancestral haplotypes and the highest genetic diversities, Australia stands out as the most likely birthplace for the Oreomyrrhis clade, followed by New Guinea. In the atpB-rbcL network, the ancestral haplotype and an interior haplotype adjacent to it are found in multiple regions, suggesting that initial range expansions into Taiwan, New Guinea/Australia, and the New World each involved at least two independent dispersals.


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1 - Academia Sinica, Research Center for Biodiversity, 128, Sec. 2, Academia Rd, Nankang, Taipei, 115, Taiwan
2 - Washington University, Biology, Campus Box 1229, 1 Brookings Drive, St. Louis, Missouri, 63130-4899, USA

Keywords:
Alpine
Apiaceae
Biogeography
long-distance dispersal
Oreomyrrhis clade of Chaerophyllum
South Pacific.

Presentation Type: Oral Paper:Papers for Topics
Session: CP01
Location: Boulevard B/Hilton
Date: Monday, July 9th, 2007
Time: 11:00 AM
Number: CP01011
Abstract ID:1637


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