Neupane, Suman , Motley, Timothy J. .
Search for “true Hedyotis” (Rubiaceae) in Asia and its biogeographic implications.
Hedyotis s.l. is a pantropical genus in the Rubiaceae family with a disputed taxonomic history. Recent molecular studies revealed a polyphyletic Hedyotis s.l. and suggest the name Hedyotis to be restricted only to the shrubby and septicidal dehiscing, capsular-fruited species distributed in tropical Asia. The purpose of this study was to further sample members belonging to this clade and test the monophyly among shrubby Asian Hedyotis which is considered “true Hedyotis” (Hedyotis s.s.). Once a monophyletic lineage is identified we will infer the biogeographical origins and history of Hedyotis. Maximum Parsimony and Bayesian Inference were used to analyze ITS and trnL-F sequence data with increased sampling from China and Sri Lanka. Results of these analyses produced two separate clades of shrubby Asian Hedyotis species, each with septicidal capsules. Each clade represents an Asian lineage derived from independent migration events from out of Africa (Initial Gondwana). The first migration event possibly occurred by rafting during early Cenozoic via the Indian tectonic plate. This lineage includes species of Hedyotis with special type of septicidal capsule, termed diplophragmous and distributed in Asia (Sri Lanka, India, Nepal, China, and Southeast Asia) and Micronesia. The second, subsequent migration was of a group of septicidal (non-diplophragmous), shrubby, Asian species of Hedyotis. This lineage continued to disperse through Asian tropics to the islands of the western Pacific which are sister to indehiscent Hedyotis species and Hawaiian and Pacific species of Kadua. The evolution of various type of fruit dehiscence and insular woodiness are major morphological adaptations in the genus. Character optimization of morphological characters indicates that secondary growth and septicidal capsules have evolved multiple times within the clades of Hedyotis s.l.
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1 - Old Dominion University, Department of Biological Sciences, 110 Mills Godwin Building/45th St, Norfolk, VA, 23529-0266, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 552B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 10:00 AM