The phylogeographic structure and genetic differentiation of Polyprion oxygeneios and Polyprion americanus in the Southern Hemisphere based on mitochondrial DNA control region sequences and microsatellite DNA genotyping

The genus Polyprion, commonly known as Wreckfish, is comprised of two species: Polyprion oxygeneios, limited to continental, insular, and seamount slopes in the Southern Hemisphere; and P. americanus, widely distributed in both the Northern and Southern Hemisphere. Polyprion support recreational and commercial fisheries off the Juan Fernandez Islands, Chile, Australia, and New Zealand, and although the fishery is relatively small in tonnage, its market value is high per kilo when compared to other species. Polyprion are long-lived, slow growing, and late to mature. These are life history characteristics that make a species vulnerable to over-fishing. Understanding the stock structure of Polyprion is important for fisheries management plans to be properly aligned to reproductive units and natural population boundaries. There has been speculation that more than two species of Polyprion exist in the Southern Hemisphere, which is an issue that needs to be more thoroughly studied. The aim of this thesis research was to investigate the population genetic structure of Polyprion in the Southern Hemisphere and determine whether there is a significant level of genetic differentiation between the Atlantic, Indian and Pacific ocean basins. The two specific objectives were to: 1) determine the levels of genetic variation and differentiation among Polyprion collectionsites from Australia and New Zealand, and 2) test whether the taxonomy of Polyprion was supported by genetic data. To do this, DNA sequences of the mitochondrial DNA (mtDNA) control region and genotypes from nine microsatelliteDNA (msatDNA) loci were used.