Lawler_whole_thesis.pdf (11.31 MB)
Conservation genetics of handfishes : Family Brachionichthyidae
thesisposted on 2023-05-28, 00:24 authored by Lawler, MM
This study investigated the conservation genetics of the handfishes, Family Brachionichthyidae. Two separate genetic investigations were undertaken. The first examined the population genetics of the spotted handfish, Brachionichthys hirsutus and the second examined the molecular phylogeny of the members of the Family Brachionichthyidae. Population genetics: A PCR based RFLP (restriction fragment length polymorphism) method was used to investigate the population genetics of the spotted handfish. An approximately 800 base-pair fragment of the mitochondrial D-loop was amplified, via a PCR based reaction, for 82 spotted handfish from four sites across the entire species' range. This fragment was digested with six restriction endonucleases, Hae/II, Hin/I, Aflll, Bsll, Bstul and Rsal. The restriction profiles were compared across the four sites. Genetic distance, sequence divergence and population subdivision were all calculated. Low genetic variation was found with sequence divergence of around 0. 06%. A suggested population structure based on the six restriction endonucleases grouped the two lower Derwent River sites together as one population, while the remainder of the sites appeared to represent the ancestral population. Molecular Phylogeny: The molecular phylogenetic relationships in the Family Brachionichthyidae were investigated by direct sequencing of the 16S rRNA and cytochrome oxidase I mitochondrial DNA genes. PCR was used to amplify a 614 base-pair fragment of the 16S rRNA and a 543 base-pair fragment of the cytochrome oxidase I genes. Five species were examined, with three of these having alternative species morphs. Parsimony analysis, maximum likelihood and distance analysis were used to infer phylogenetic relationships. The resultant molecular phylogeny suppo1ted the status of two genera, Brachionichthys and Sympterichthys. Based on morphological studies in progress, the molecular phylogeny supports the morphological taxonomy of this family . The species morphs of the Australian handfish, the warty handfish and the red handfish, all appeared to be sub-specific relationships. Further investigation of these species morphs is required.
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