Abstract Detail

Biogeography

Cantley, Jason T. [1], Keeley, Sterling [2], Swenson, Nathan [3], Markey, Adrienne [4].

Dioecy and woodiness promote evolutionary diversification of insular Coprosma (Rubiaceae), one of the largest and most widely distributed genera in the Pacific.

The origins and key innovations promoting biodiversity and successful establishment of angiosperms on islands are often proposed to include such vegetative attributes as gigantism and woodiness, reproductive features such as self-compatibility and dioecy, and dispersal via flotation, wind or birds. However, the importance of such features remains undocumented for many taxa, especially for those on remote islands of the Pacific. Coprosma (Rubiaceae), is one of the largest and most widely distributed genera across the Pacific, with ca. 110 species and a distribution that encompasses virtually every Pacific island group between Australia, Borneo, Hawaii and the Juan Fernandez Islands. To explore the importance of woodiness and dioecy of Coprosma, phylogenetic reconstructions were used to map these characters for 106 species using two nuclear (ITS and ETS) and two chloroplast DNA regions (rps16 intron and trnQ-rps16). Additionally, molecular clocking analyses were performed employing a relaxed clock as implemented in BEAST. Our analyses suggest that the innovation of dioecy and a woody habit are among the factors promoting the evolutionary diversification of Coprosma, which originated in New Zealand 15-20 Ma. Three major (and numerous minor) dispersals from New Zealand into the remote Pacific are documented. Furthermore, at least seven remote Pacific localities (Austral, Chatham, Hawaii, Kermadec, Lord Howe, Norfolk and Samoan Islands), as well as Australia and New Guinea have been colonized by Coprosma on at least two or more separate occasions. Dispersal patterns across the Pacific appear stochastic, and are perhaps concordant with bird dispersal patterns over many millions of years. This pattern is in contrast with the bisexual and herbaceous sister genus Nertera, in which only one taxon is widespread throughout the Pacific. Our new understanding on the evolution of Coprosma highlights perhaps one of the most complex biogeographic histories of any Pacific plant genus investigated to date and adds to a growing amount of research investigating the connections of Pacific floras.

Broader Impacts:

1 - University of Hawaii at Manoa, Botany, 3190 Maile Way, St. John 101, Honolulu, HI, 98622, USA
2 - University of Hawaii, DEPT. BOTANY, 3190 MAILE WAY, ROOM 101, Honolulu, HI, 96822-2279, USA
3 - Michigan State University, Plant Biology, East Lancing, MI, 48824, USA
4 - Environment and Conservation, 1 Kensington, Kensington, Western Australia, Australia

Keywords:
Austral Islands
Australia
Chatham Islands
dioecy
Hawaii
Pacific Biogeography
key innovation
woodiness
Lord Howe
Samoa
New Guinea
New Zealand
Kermadec
Norfolk
Marquesas.

Presentation Type: Oral Paper:Papers for Topics
Session: 38
Location: Marlborough A/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 10:15 AM
Number: 38007
Abstract ID:243
Candidate for Awards:George R. Cooley Award