Phylogeny and Evolution of Mycorrhizal Associations in the Myco-heterotrophic Hexalectris Raf. (Orchidaceae : Epidendroideae)

 
 
 
 

Phylogeny and Evolution of Mycorrhizal Associations in the Myco-heterotrophic Hexalectris Raf. (Orchidaceae : Epidendroideae)

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dc.contributor.advisor Watson, Dr. Linda E. en_US
dc.contributor.author Kennedy, Aaron H. en_US
dc.date.accessioned 2009-04-10T10:36:30Z
dc.date.available 2009-04-10T10:36:30Z
dc.date.created 2009 en_US
dc.date.issued 2009-04-10T10:36:30Z
dc.identifier.uri http://rave.ohiolink.edu/etdc/view?acc_num=miami1232724178 en_US
dc.identifier.uri http://hdl.handle.net/2374.OX/108602
dc.description Some plant species have abandoned an autotrophic life style and obtain their carbon and mineral nutrition exclusively from mycorrhizal fungi. Although myco-heterotrophic species have evolved in many plant families, they are most common in the Orchidaceae. Several myco-heterotrophic orchid species have been shown to associate with a very narrow range of ectomycorrhizal forming fungi, revealing a high degree of mycorrhizal specificity. However, these studies have often investigated single or few, often unrelated, species without support for their monophyly or knowledge of their phylogenetic relationships. Using primarily molecular methods and phylogenetic analyses, this dissertation investigates i) the monophyly and circumscription of Hexalectris species, ii) interspecific phylogenetic relationships within Hexalectris, iii) the identities of the mycorrhizal fungi that associate with each Hexalectris species, iv) the breadth of mycorrhizal associations within Hexalectris and within each of its species, and v) uses a Hexalectris phylogeny as a framework for investigating mycorrhizal specificity and patterns of associations. The monophyly of H. warnockii, H. grandiflora, H. brevicaulis, and H. nitida, plus the H. spicata species complex, are well supported. The remaining species are not monophyletic, prompting the recircumscription of H. spicata s.l. as H. spicata and H. arizonica, H. revoluta s.l. as H. revoluta and H. colemanii, and H. fallax as a synonym of H. parviflora. Extreme specificity with ectomycorrhizal agaricomycete fungi was identified in each Hexalectris species. Hexalectris warnockii associates exclusively with members of the Thelephoraceae; H. brevicaulis and H. grandiflora associate exclusively with members of Russulaceae and Sebacinaceae subgroup A; the remaining species, all members of the H. spicata complex, associate strictly with members of Sebacinaceae subgroup A. Optimizing these associations onto a Hexalectris phylogeny reveals that, with one exception, each Hexalectris species associates with a different clade or group of fungal clades, and that shifts in association from one group of fungi to another occurred during each speciation event in the evolutionary history of this genus. en_US
dc.format application/pdf en_US
dc.format 97p. en_US
dc.rights unrestricted en_US
dc.rights Copyright and permissions information available at the source archive en_US
dc.subject Orchidaceae en_US
dc.subject orchid en_US
dc.subject Hexalectris en_US
dc.subject phylogenetics en_US
dc.subject molecular systematics en_US
dc.subject mycorrhizae en_US
dc.subject myco-heterotrophy en_US
dc.subject mycoheterotrophy en_US
dc.subject ITS en_US
dc.subject plastid en_US
dc.subject specificity en_US
dc.subject tripartite en_US
dc.subject ectomycorrhizae en_US
dc.title Phylogeny and Evolution of Mycorrhizal Associations in the Myco-heterotrophic Hexalectris Raf. (Orchidaceae : Epidendroideae) en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name PhD en_US
dc.degree.level doctoral en_US
dc.degree.discipline Botany en_US
dc.degree.grantor Miami University en_US
dc.contributor.publisher Miami University / OhioLINK en_US

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