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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Molecular systematics of the Lomandra Labill. Complex (Asparagales: Laxmanniaceae).Donnon, Matthew J. January 2010 (has links)
The “Lomandra complex” (or Lomandra grouping) is an informally recognised grade resulting from the subdivision of the Laxmanniaceae into two groups (Conran, 1998); the ‘Lomandra complex” (Acanthocarpus, Chamaexeros, Lomandra, Romnalda and Xerolirion), and the remainder as the Arthropodoids (Arthropodium, Chamaescilla, Cordyline, Eustrephus, Laxmannia, Murchisonia, Sowerbaea, Thysanotus and Trichopetalum). Laxmanniaceae are an Australiacentred, tropical to temperate family of 14 genera with around 180 species from Australasia, SE Asia, the Mascarenes, New Caledonia, New Guinea, New Zealand, North and South America and the Pacific Islands. There have been no detailed phylogenetic studies in Laxmanniaceae and the relationships within and between the genera is poorly understood. This study utilised molecular data from chloroplast trnL-F and nuclear ribosomal ITS2 regions analysed with maximum parsimony and bayesian inference methods to reconstruct the phylogeny of the genera of the ‘Lomandra complex’, using species of Arthropodium, Eustrephus, Laxmannia and Thysanotus as outgroups. The molecular phylogeny shows that Lomandra forms four primary clades; with members from the classical anatomy, inflorescence-defined section and series distributed amongst these, typically in large islands. The monotypic genus Xerolirion resides deeply within Lomandra, raising questions about the appropriateness of this genus. Additionally, the other genera of the Lomandra complex (Acanthocarpus, Chamaexeros and Romnalda) form a clade positioned sister to one of four primary Lomandra clades, but nested inside Lomandra sens. lat., indicating a closer relationship between these genera than previously thought. The affiliation of these bisexual, hermaphroditic genera within the otherwise unisexual, dioecious Lomandra clade supports the recognition of the ‘Lomandra complex’ as an expanded genus, Lomandra; and represents either an example of the evolution of unisexuality followed by reversion, or else multiple losses of hermaphrodite flowers. Morphological and anatomical data were obtained for leaf and floral macroscopic characters, mid-leaf section anatomy and cuticle microscopic features and analysed with maximum parsimony and bayesian inference methods to reconstruct the anatomical phylogeny. These data were also utilised to generate a DELTA key for identifying species of Lomandra from a combination of macroscopic morphological and microscopic leaf anatomical features. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1385938 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2010
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Phylogeny and Molecular Evolution of the Voltage-gated Sodium Channel Gene scn4aa in the Electric Fish Genus GymnotusXiao, Dawn Dong-yi 19 March 2014 (has links)
Analyses of the evolution and function of voltage-gated sodium channel proteins (Navs) have largely been limited to mutations from individual people with diagnosed neuromuscular disease. This project investigates the carboxyl-terminus of the Nav paralog (locus scn4aa 3’) that is preferentially expressed in electric organs of Neotropical weakly-electric fishes (Order Gymnotiformes). As a model system, I used the genus Gymnotus, a diverse clade of fishes that produce species-specific electric organ discharges (EODs). I clarified evolutionary relationships among Gymnotus species using mitochondrial (cytochrome b, and 16S ribosome) and nuclear (rag2, and scn4aa) gene sequences (3739 nucleotide positions from 28 Gymnotus species). I analyzed the molecular evolution of scn4aa 3’, and detected evidence for positive selection at eight amino acid sites in seven Gymnotus lineages. These eight amino acid sites are located in motifs that may be important for modulation of EOD frequencies.
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Phylogeny and Molecular Evolution of the Voltage-gated Sodium Channel Gene scn4aa in the Electric Fish Genus GymnotusXiao, Dawn Dong-yi 19 March 2014 (has links)
Analyses of the evolution and function of voltage-gated sodium channel proteins (Navs) have largely been limited to mutations from individual people with diagnosed neuromuscular disease. This project investigates the carboxyl-terminus of the Nav paralog (locus scn4aa 3’) that is preferentially expressed in electric organs of Neotropical weakly-electric fishes (Order Gymnotiformes). As a model system, I used the genus Gymnotus, a diverse clade of fishes that produce species-specific electric organ discharges (EODs). I clarified evolutionary relationships among Gymnotus species using mitochondrial (cytochrome b, and 16S ribosome) and nuclear (rag2, and scn4aa) gene sequences (3739 nucleotide positions from 28 Gymnotus species). I analyzed the molecular evolution of scn4aa 3’, and detected evidence for positive selection at eight amino acid sites in seven Gymnotus lineages. These eight amino acid sites are located in motifs that may be important for modulation of EOD frequencies.
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