Evolution and biodiversity of the Ixoroideae (Rubiaceae)
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
The phylogenetic relationships within subfamily Ixoroideae of the coffee family are investigated by phylogenetic reconstruction of molecular data, including regions of the chloroplast DNA (matK, ndhF, rbcL, rps16, trnH-psbA, trnS-G, and trnT-F), and the nuclear ribosomal DNA (ITS). The evolution of morphological characters within the group are inferred, with focus on characters used in classification. Ixoroideae have primarily been characterized by secondary pollen presentation, contorted corolla aestivation, and fleshy fruits. Secondary pollen presentation appears synapomorhic of a clade comprising the Ixoroideae crown group together with Retiniphyllum, whereas contorted corolla aestivation has evolved earlier and is synapomorphic for the crown group, Retiniphyllum, and Steenisia. Capsules likely represent a plesiomorphy from which various dry or fleshy indehiscent fruits have evolved independently in different clades. Reductions in seed number have also occured in many clades, none of which shows a secondary increase in the number of seeds.
Within Ixoroideae, the phylogeny and tribal delimitations of Alberteae and Condamineeae are studied in more detail. The former appears restricted to Alberta, Nematostylis, and Razafimandimbisonia, a new genus described here. The Condamineeae are a diverse tribe largely unresolved in previous molecular phylogenetic studies. Our results support a synonymization of both Calycophylleae and Hippotideae, because these are nested within the Condamineeae. Ancestral state reconstructions indicate that intrapetiolar stipules, poricidal anthers, and protogyny, otherwise uncommon characters in Rubiaceae, all have evolved more than once in the Condamineeae.
The rare genera Jackiopsis, Glionnetia, and Trailliaedoxa previously not included in molecular phylogenetic analyses, are all found nested within the Ixoroideae, and their systematic positions are discussed. The genera Bathysa, Calycophyllum, Elaeagia, and Rustia do not appear monophyletic. Consequently, resurrections of the names Holtonia, Schizocalyx, and Semaphyllanthe, and synonymizations of Phitopis (as Schizocalyx) and Tresanthera (as Rustia) are proposed. Also proposed are five new tribal names for clades that are not associated with any previously described tribes in the phylogenetic hypotheses presented.
Place, publisher, year, edition, pages
Stockholm: Department of Botany, Stockholm University , 2010. , 28 p.
Alberteae, character evolution, classification, Condamineeae, fruit evolution, Ixoroideae, phylogenetics, pollen presentation, Rubiaceae, systematics, taxonomy
Research subject Plant Systematics
IdentifiersURN: urn:nbn:se:su:diva-48850ISBN: 978-91-7447-198-4OAI: oai:DiVA.org:su-48850DiVA: diva2:376046
2011-01-14, föreläsningssalen, Botanicum, Lilla Frescativägen 5, Stockholm, 10:00 (English)
Knapp, Sandra, Dr.
Bremer, Birgitta, ProfessorRazafimandimbison, Sylvain, Dr.Eriksson, Torsten, Dr.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.2010-12-222010-12-092010-12-14Bibliographically approved
List of papers