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A Molecular Phylogeny of the Lythraceae and Inference of the Evolution of Heterostyly

Morris, Julie A.
http://rave.ohiolink.edu/etdc/view?acc_num=kent1185584449

Abstract Details

2007, PHD, Kent State University, College of Arts and Sciences / Department of Biological Sciences.
Lythraceae is comprised of approximately 32 genera and 600 species of flowering plants with a worldwide distribution. In addition to having several economically and ecologically important taxa, Lythraceae is one of very few families exhibiting heterostyly, a rare reproductive polymorphism in plants in which flower morphs differ reciprocally in the height of their anthers and stigmas. The mode of inheritance, function, and adaptive significance of heterostyly have been the focus of extensive study, however its evolutionary history remains poorly understood. Well resolved phylogenies of groups having both heterostylous and homostylous members, such as the Lythraceae, provide evidence to evaluate alternate evolutionary hypotheses. Extreme variations in habit combined with a generalized floral morphology have obscured relationships among these genera based on morphological characters. Previous molecular analyses have been unable to distinguish basal relationships within the family, complicating both taxonomic classification and inferences of ancestral characters for the study of morphological evolution. This dissertation describes the most comprehensive molecular phylogenetic analyses to date of Lythraceae, and its type genus Lythrum –a relatively large genus that also contains both heterostylous and homostylous species. These new analyses permit evaluation of current taxonomy, and provide a framework for studying the evolution of heterostyly at both taxonomic levels. Adding new molecular data to previous sequence data using multiple inference techniques, the resulting topologies are congruent and generally well resolved, but challenge the current taxonomic classification of these taxa. At the family level, terminal clades are more stable than in previous analyses, however, support for basal relationships remains relatively low, possibly because of an early rapid radiation. Within Lythrum, diversification appears to have occurred more recently, and strong biogeographical patterns exist. Ancestral character state reconstruction of heterostyly was performed using the Lythraceae phylogeny. Various reconstruction methods and character-weighting schemes provide ambiguous results, with estimates ranging from 5 independent origins of heterostyly, to a single origin for the family followed by repeated parallel reversions to homostyly. While the direction of change remains uncertain, multiple changes have undoubtedly occurred, and some evidence suggests that a single evolutionary gain followed by multiple parallel losses may be likely.
Andrea Case (Advisor)
107 p.
Lythraceae; Lythrum; heterostyly; phylogeny

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Citations

  • Morris, J. A. (2007). A Molecular Phylogeny of the Lythraceae and Inference of the Evolution of Heterostyly [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1185584449

    APA Style (7th edition)

  • Morris, Julie. A Molecular Phylogeny of the Lythraceae and Inference of the Evolution of Heterostyly. 2007. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1185584449.

    MLA Style (8th edition)

  • Morris, Julie. "A Molecular Phylogeny of the Lythraceae and Inference of the Evolution of Heterostyly." Doctoral dissertation, Kent State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=kent1185584449

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Kent State University and OhioLINK.