Phylogeny and biogeography of Rhododendron section Vireya

• Main Author: Brown, Gillian Kim.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Melbourne 2004
• Subjects: Rhododendrons; Rhododendrons > Phylogeny; Rhododendrons > Geographical distribution; Rhododendrons > Varieties; Greenland
• Online Access: http://hdl.handle.net/11343/341605

Typescript (photocopy) Thesis (PhD) -- University of Melbourne, School of Botany, 2004 Includes bibliographical references (leaves 229-263) Rhododendron L. is a large genus consisting of over 1000 species (Chamberlain et al. 1996). It extends from North America to Russia, and from Greenland to north-eastern Australia (Cowan 1949). The taxonomic history of the genus has been complex because of its size and diverse range of morphological variation; at present Rhododendron is divided into eight subgenera, which are further divided into sections and subsections. One of the most morphologically diverse groups of Rhododendron is section Vireya (Blume) Copel.f. of subgenus Rhododendron, the lepidote rhododendrons. Section Vireya has a unique distribution for the genus, being predominantly found throughout the Malesian Island Archipelago and extending into neighbouring areas, west to the Himalayas and east to north-eastern Australia and the Solomon Islands. The defining characteristics of section Vireya � the possession of seeds with tailed appendages at both ends, the twisting of capsule valves after opening, placentas that separate as thread-like structures from the central axis as the capsule opens � are subject to exceptions, although vireyas are easily distinguished from other rhododendrons by their general appearance. The alpha taxonomy of section Vireya is relatively well understood, although the evolutionary history of the group, the largest section in the genus, has not been studied. This thesis aims to bridge this gap in our knowledge. Phylogenetic analyses of three DNA regions, two chloroplast (psbA-trnH and trnT-trnL intergenic spacers) and one nuclear (Internal Transcribed Spacer), were conducted. The results of each analysis were generally congruent, with clades relating strongly to geographic areas. Section Vireya as currently circumscribed is shown to be not monophyletic, and only three of the seven subsections are resolved as monophyletic � Malayovireya Sleumer, Siphonovireya Sleumer and ...