Percy, Diana , Garver, Adam M. , Wagner, Warren L. , James, Helen F. , Cunningham, Cliff , Miller, Scott E. , Fleischer, Robert C. .
Dating the origin of Hawaiian Metrosideros (Myrtaceae): progressive island colonization and the evolution of ecological dominance.
Knowledge of the evolutionary history of plants that are ecologically dominant in modern ecosystems is critical to understanding the historical development of those ecosystems. In particular, we often observe specialized interactions and apparent co-diversification of animals with the plants they depend on. In the Hawaiian Islands, Metrosideros polymorpha is an ecologically dominant species and is also highly polymorphic in both growth form and ecology. Using 10 non-coding chloroplast regions we investigated haplotype diversity in the five currently recognized Hawaiian Metrosideros species and an established outgroup, M. collina, from French Polynesia. Multiple haplotype groups were found, but these did not match morphological delimitations. Alternative morphologies sharing the same haplotype, as well as similar morphologies occurring within several distinct island clades, could be the result of developmental plasticity, parallel evolution, or chloroplast capture. The geographical structure of the data is consistent with a pattern of age progressive island colonizations and suggests de novo intra-island diversification. If single colonization events resulted in a similar array of morphologies on each island, this would represent parallel radiations within a single, highly polymorphic species. However, we were unable to resolve whether the pattern is instead explained by ancient introgression and incomplete lineage sorting resulting in repeated chloroplast capture. Ongoing nuclear microsatellite work should help to clarify these patterns. Using several calibration methods, we estimate the colonization of the Hawaiian Islands to be potentially as old as 3.9 (-6.3) mya with an ancestral position for Kaua`i in the colonization and evolution of Metrosideros in the Hawaiian Islands. This would represent a more ancient arrival of Metrosideros to this region than previous studies have suggested.
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1 - University of British Columbia, Department of Botany and Centre for Plant Research, 3529-6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada
2 - Smithsonian Institution, Center for Conservation and Evolutionary Genetics, National Zoological Park, Box 37012, MRC 5503, Washington, DC, DC, 20013, USA
3 - National Museum of Natural History, Smithsonian Institution, Botany, P.O. Box 37012, MRC 166, Washington, DC, 20013-7012, USA
4 - National Museum of Natural History, Smithsonian Institution, Division of Birds, PO Box 37012, MRC 116, Washington, DC, 20013-7012, USA
5 - Duke University, Biology Department, Biology Department, Duke University, Box 90338, Durham, NC, 27708, USA
6 - Smithsonian Institution, National Museum of Natural History, Box 37012, Washington, DC, DC, 20013, USA
7 - National Zoological Park, Smithsonian Institution, Center for Conservation and Evolutionary Genetics, 3001 Connecticut Ave., NW, Washington, DC, 20008-0551, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Wednesday, July 30th, 2008
Time: 8:30 AM