Monocotyledonous plants are a well-circumscribed lineage comprising 25% of all angiosperm species, including many agriculturally and ecologically important species (e.g., grasses, gingers, palms, orchids, lilies, yams, pondweeds, seagrasses, aroids). These taxa possess nearly the full breadth of vegetative and floral morphology seen across angiosperms, dominate a variety of ecosystems, and exhibit considerable genomic complexity, including the largest genome sizes of all plants. The opportunities afforded by this wealth of variation include evaluating patterns of morphological evolution, genomic change, and geographic radiation. This same variation, however, presents unique challenges to establishing an accurate phylogenetic framework as the foundation for evolutionary analysis.
This dissertation documents three vignettes in monocot evolution, each highlighting different taxonomic scales and relevant questions to the diversification and significance of both organismal (life history, biogeography, morphology) and genomic (genome size, molecular evolution) characteristics. Chapter 2 uses molecular sequence data from all three genomic partitions (nuclear and both organellar genomes) to infer evolutionary relationships in monocots. Subsequent divergence time and diversification analysis suggests that radiation of major monocot lineages was highly dependent on the origin of other plant and animal lineages. Chapter 3 evaluates a taxonomic classification system in the Tradescantia alliance (Commelinaceae, Commelinales), a group of closely related genera exhibiting kaleidoscopic variation in life history and genomic traits. The phylogeny developed for the alliance is used to re-interpret evolution of taxonomically relevant morphological characters and to test for correlations between genome size and life history/biogeography. Finally, Chapter 4 evaluates a methodological approach to genome sequencing in two lineages of monocots. Grasses (Poaceae, Poales) as a model system are used to test the efficacy of such methods. Non-model Asparagales (agave, onion, asparagus), with large genomes and a paucity of published sequence data, are used to support the ability of these genome sequencing methods to provide ample data for ecological and evolutionary studies. Each of these examples highlights the ability of monocots to serve as test cases for different types of evolutionary questions.
|Advisor:||Pires, J. Chris|
|School:||University of Missouri - Columbia|
|School Location:||United States -- Missouri|
|Source:||DAI-B 73/11(E), Dissertation Abstracts International|
|Subjects:||Genetics, Evolution and Development, Systematic|
|Keywords:||Genomes, Monocots, Phylogenetics, Plant evolution|
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