Systematics/Phytogeography / Taxonomie/ Section
Birch, Joanne L. , Morden, Clifford W. , Keeley, Sterling C. .
A preliminary phylogeny of Astelia (Asteliaceae): implications for identifying pathways of long-distance dispersal in the Pacific.
The influence of long-distance dispersal in determining the composition of both island and continental floras is increasingly well documented. However, patterns of long-distance dispersal in the Pacific Basin remain poorly understood, with many Pacific taxa yet to be placed in a phylogenetic context. A phylogenetic study of the flowering plant genus Astelia is underway to investigate the evolution and biogeography of this genus.
With approximately 25 species, Astelia is the largest genus in the Asteliaceae. It has a center of diversity in New Zealand and is distributed on three Gondwanan landmasses (Australia, New Zealand, and South America) and on six island archipelagos in the Pacific and Indian Oceans. Skottsberg (1934) hypothesized that Astelia was of Gondwanan origin and considered the current distribution to be the result of multiple dispersal events into the Pacific. The phylogenetic position of 21 Astelia species was evaluated using sequence data from the chloroplast genome (trnL intron, psbA-trnH, and trnK-rps16 intergenic spacers). Inferred phylogenies based on individual and combined data sets indicate that Astelia is paraphyletic as currently circumscribed, and includes Collospermum, which was previously segregated from Astelia by Skottsberg (1934). The circumscription of subgenera does not accurately reflect the evolutionary history of the genus. The New Zealand Astelia are not monophyletic as the New Caledonian, Society Island, and Mascarene Island Astelia species are each more closely related to New Zealand species than to each other. This is consistent with a dispersal hypothesis in which multiple long-distance dispersal events are necessary to explain the current distribution of Astelia in the Pacific.
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1 - University of Hawaii, Botany Department, 3190 Maile Way, Honolulu, HI, 96822, USA
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM