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Patterns and Mechanisms of Evolution of Island Plants

Crawford, Daniel J. [1], Stuessy, Tod F. [2], Anderson, Gregory J. [3], Bernardello, Gabriel [4], Jensen, Richard [5], Ruiz, Eduardo [6], Baeza, Carlos M. [6], Silva O., Mario [6].

Genetic diversity and reproductive biology of the flowering plants of the Juan Fernandez Islands, Chile.

The Juan Fernandez archipelago consists of two small islands (each 50 km2) of volcanic origin located 660 km off the coast of central Chile. The two islands of ages 4.0 and 1-2 million years harbor a small native angiosperm flora of 155 species, with over 60%  endemic. Investigations of the origin and evolution of the endemic flora include studies of correlations between life history traits and genetic diversity within and among populations. Most endemics are hermaphroditic, perennial herbs, shrubs or trees; 9% are dioecious and 9% monoecious. Fourteen percent of the species have been examined for compatibility, with 85% self compatible. Autogamy is low because of dichogamy, with selfing achieved by geitonogamy. Wind pollination is most frequent, and 14 species are hummingbird pollinated. There is no documented insect pollination. Allozyme variation was examined in 29 endemic and one native species. As in many island endemics, average diversity is low in most species. Correlations found between life history traits and allozyme diversity in surveys of flowering plants were not detected in the insular endemics. For example, differences were not found in levels of species and population diversity between selfers and wind-pollinated plants. Average divergence among populations of insular species is high, but differences detected for angiosperms as a whole (e.g., animal versus wind-pollinated) were not found in the islands. The allozyme results indicate that factors associated with colonization and diversification in the insular setting (bottlenecks, inbreeding, etc.) "override" the life history-diversity correlations found in angiosperms as a whole. Flowers of the island endemics often retain features of their colonizing ancestors, and do not have the suite of features expected for the mode of pollination. The population structure and floral morphology of the island endemics reflect both historical-phylogenetic factors and evolutionary processes in the insular setting.

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1 - University of Kansas, Department of Ecology & Evolutionary Biology, Natural History Museum and Biodiversity Research Center, 1200 Sunnyside Avenue, Lawrence, Kansas, 66045-7534, USA
2 - University of Vienna, Institute for Botany, Dept. of Higher Plant Systematics and Evolution, Rennweg 14, Vienna, A-1030, Austria
3 - University of Connecticut, Department of Ecology & Evolutionary Biology, 75 North Eagleville Rd. U-3043, Storrs, Connecticut, 06269-3043, USA
4 - Universidad De Cordoba, Instituto Multidisciplinario De Biologia Vegetal (Imbiv), Museo Botanico, Casilla De Correo 495, Cordoba, 5000, Argentina
5 - Saint Mary's College, Department of Biology, Notre Dame, Indiana, 46556, USA
6 - Universidad De Concepción, Facultad De Ciencias Naturales Y Ocean., Casilla 160-C, Concepción, VIII Region, , Chile

island, genetic diversity, reproductive biology
island, genetic diversity
reproductive biology.

Presentation Type: Symposium or Colloquium Presentation
Session: 50-1
Location: Salon J - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 1:30 PM
Abstract ID:260

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