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Abstract Detail



Biogeography

Chau, Marian [1], Funk, Vicki [2], Cantley, Jason [1], Keeley, Sterling [3].

The Story of Nehe: Biogeography of widespread Melanthera (Heliantheae: Compositae) and the origin of a Hawaiian radiation.

The flora of Hawaii is characterized by endemism and adaptive radiation, a reflection of the archipelago’s volcanic origin, extreme isolation, and long-distance dispersal events from sources worldwide. The source and timing of colonization events to Hawaii have been investigated for a number of genera, but the two closely related genera Lipochaeta and Melanthera (Heliantheae: Compositae; referred to in Hawaiian as nehe) comprise a large radiation of 16 endemic species that has escaped investigation. Other species of Melanthera are also distributed around the globe. To gain an understanding of the source and timing of colonization of nehe in Hawaii, we constructed a phylogeny of 90 taxa, including all extant species of nehe, 13 species of non-Hawaiian Melanthera, and several outgroups in subtribe Ecliptinae, using DNA sequences from two nuclear (ITS, ETS) and two chloroplast (trnH-psbA, trnQ-rps16) non-coding regions. Results show that globally Melanthera s.l. (including Lipochaeta) is a monophyletic group with an origin in the Neotropics, consisting of three major lineages: an African clade with South American taxa nested within, a southeastern U.S. clade, and an Asian/Pacific clade including all Hawaiian taxa. The Hawaiian species form a monophyletic group that is sister to the Asian and South Pacific taxa. Dated phylogenies indicate that the Hawaiian clade may have arisen within the age range of the current high islands of Hawaii (ca. 5 Ma), but there is also the possibility that colonization occurred in the Northwestern Hawaiian Islands (currently low islands and atolls). Although species of nehe can be found in a diverse range of habitats, about half inhabit coastal strand ecosystems, including M. integrifolia, which is found on all the main islands and Laysan and Kure atolls. Several non-Hawaiian Melanthera are also coastal species, including the widespread M. biflora, which occurs on many continental coasts and most islands in the Indian and Pacific Oceans (excluding Hawai'i), and is known to have seeds that remain viable after extended flotation in salt water. We hypothesize that the ancestor of Hawaiian nehe arose in a coastal habitat as a result of long-distance ocean dispersal, followed by adaptive radiation throughout the Hawaiian Islands.

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1 - University of Hawaii At Manoa, Botany, 3190 Maile Way, Room 101, Honolulu, HI, 96822, USA
2 - Smithsonian Institution, DEPT OF BOTANY-NHB 166, P.O. Box 37012, Washington, DC, 20013-7012, USA
3 - University of Hawaii, DEPT. BOTANY, 3190 MAILE WAY, ROOM 101, Honolulu, HI, 96822-2279, USA

Keywords:
Compositae
Hawaii
biogeography
Long Distance Dispersal
Adaptive Radiation.

Presentation Type: Oral Paper:Papers for Topics
Session: 38
Location: Marlborough A/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 11:00 AM
Number: 38010
Abstract ID:906
Candidate for Awards:George R. Cooley Award


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