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Diversification of Galium within Tribe Rubieae (Rubiaceae): Evolution of Breeding Systems, Species Complexes, and Gene Duplication

Show simple item record Soza, Valerie 2010-12-10T21:09:07Z 2010-12-10T21:09:07Z 2010
dc.identifier.citation Soza, V. L. and R. G. Olmstead. 2010. Molecular systematics of tribe Rubieae (Rubiaceae): evolution of major clades, development of leaf-like whorls, and biogeography. Taxon 59: 755—771 (; Soza, V. L. and R. G. Olmstead. 2010. Evolution of breeding systems and fruits in New World Galium and relatives (Rubiaceae). American Journal of Botany 97: 1630—1646 ( en_US
dc.identifier.issn 0040-0262; 0002-9122
dc.description.abstract Tribe Rubieae is unique within Rubiaceae with its herbaceous habit, temperate distribution, and whorls of leaf-like structures. This dissertation examines the evolution of the tribe, evolution a clade within the tribe (Cruciata-Galium-Valantia [CGV] clade), and finally a section of the genus Galium (sect. Baccogalium). A molecular phylogeny of the tribe, based on three chloroplast (cp) regions, strongly supports seven major clades within the tribe. The resulting phylogeny is used to examine geographic distribution patterns and evolution of leaf-like whorls in the tribe. An Old World origin of the tribe is inferred, followed by at least eight dispersal events into North America. The ancestral whorl morphology of the tribe is inferred as composed of six organs, from which whorls of four organs are derived. Polygamy, dioecy, and hermaphroditism all occur within the CGV clade, in which dioecy is hypothesized to have evolved from hermaphroditism via polygamy. A molecular phylogeny of the CGV clade, based on cp and nuclear ribosomal data, strongly supports nine lineages of New World Galium taxa. The resulting phylogeny is used to examine evolution of breeding systems, fruit types, and fruit hairs. Dioecy is inferred to have arisen at least three times from hermaphroditism; polygamy is inferred to have arisen at least twice from dioecy and at least six times from hermaphroditism. Polygamy appears to be a terminal condition in the CGV clade and not a pathway to dioecy. Fruit characters traditionally used in the taxonomy of this group have arisen multiple times within this clade and are not reliable indicators of shared evolutionary history. Approximately 30 Galium taxa are designated rare by the California Native Plant Society, ten of which occur within G. sect. Baccogalium. Within G. sect. Baccogalium, relationships among taxa are not well resolved with either cp or nuclear data. A molecular phylogeny of the section, based on cp data, indicates that subspecies from three species complexes do not form respective monophyletic groups, which will have implications for management of rare infraspecific taxa. A molecular phylogeny based on nuclear RPB2 indicates that Galium taxa examined lack the I copy and contain a duplicated D copy. en_US
dc.description.sponsorship American Society of Plant Taxonomists, Botanical Society of America, University of Washington (UW) Department of Biology Giles Graduate Student Field Research Award, Denton Writing Fellowship, and Molecular Phylogenetics and Systematics Graduate Fellowship, UW Graduate School Stroum Endowed Minority Dissertation Fellowship, and NSF grants DEB-0542493 and EF-0431184 to Richard Olmstead en_US
dc.language.iso en_US en_US
dc.publisher International Association for Plant Taxonomy; Botanical Society of America en_US
dc.rights Copyright is held by the individual authors. en_US
dc.subject Rubieae, biogeography, leaf whorls, phylogeny, breeding systems, Cruciata, fruits, ETS, Galium, rpoB-trnC, trnC-psbM, trnL-ndhJ, Valantia, Baccogalium, RPB2 en_US
dc.title Diversification of Galium within Tribe Rubieae (Rubiaceae): Evolution of Breeding Systems, Species Complexes, and Gene Duplication en_US
dc.type Thesis en_US

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