Seeking the Phylogenetic Root of the Monocots: A Study of Paleoherb Genomes

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9873724 Duvall The monocots constitute a well-defined group of 50,000 plant species that have undoubtedly evolved from a single ancestor. However, botanists are stillunsure of the most closely related dicot, the so-called sister group of the monocots. Although the basal group of monocots is now known to be the Acoranan lineage, details regarding ancestral characters of the group are still uncertain.The monocots are known to be part of a greater evolutionary radiation of ancient herbaceous species, the paleoherbs. Relationships within over fifty species of paleoherbs will be explored using key floral characters and genes from the three plant genomes, the chloroplast, the nucleus, and the mitochondrion. Approximately 6000 base pairs of nucleotide sequence will be determined for each species. These data will be used to study phylogenetic patterns within paleoherbs and to identify the dicot sister group to themonocots.A strongly supported phylogenetic hypothesis for the dicot sister group to the monocots will be a significant contribution to our understanding of the molecular evolution and systematics of the paleoherbs and provide systematists with an appropriate reference group for further evolutionary studies. Once the phylogenetic questions have been answered, organismal characteristics in the relevant sister group taxon can be identified to determine which characters were critical to the adaptive radiation of this large group. Molecular investigation of these characters may identify key genes important to the fundamental monocot morphology. Finally, new and better supported hypotheses for the origin and radiation of monocots will be formulated.