A. J. Smolenski

Evidence of stock separation in southern hemisphere organge roughy (Hoplostethus atlanticus, Trachichthyidae) from restriction-enzyme analysis of mitochondrial DNA

Restriction enzyme analysis of mitochondrial DNA (mtDNA) was used to test for genetic homogeneity of orange roughy (Hoplostethus atlanticus) in the southern hemisphere. Two hundred and eighty-six orange roughy specimens were collected from seven general localities: the Great Australian Bight; South Australia (off southeastern Kangaroo Island); the west coast of Tasmania; the east coast of Tasmania; New South Wales; New Zealand and South Africa. Mitochondrial DNA was extracted from developing ovary tissue and analysed with 10 six-base enzymes and 3 four-base enzymes. Both forms of analysis revealed a low level of genetic diversity in this species. The six-base enzyme study found no evidence of reproductively isolated populations of orange roughy in southeastern Australian waters. However, an analysis of 107 fish with 3 four-base enzymes identified at least partial genetic separation of the New South Wales (NSW) sample of orange roughy from South Australian (off southeastern Kangaroo Island) and Tasmanian samples. This finding supports biological evidence for the presence of a distinct subpopulation of orange roughy in NSW waters. The four-base study also provided evidence of the presence of genetically distinct samples of orange roughy occurring in the same localities off southeastern Kangaroo Island from consecutive years. Additional sampling and the use of a greater number of four-base enzymes may be needed to determine if any genetic structuring exists among orange roughy south of New South Wales.

Molecular phylogeny of the Cheilodactylidae and Latridae (Perciformes: Cirrhitoidea) with notes on taxonomy and biogeography

Phylogenetic relationships among cheilodactylid and latrid fishes were estimated from cytochrome oxidase I and cytochrome b mitochondrial DNA sequences. Two South African cheilodactylids, Cheilodactylus fasciatus and Cheilodactylus pixi, were divergent from the remaining members of their genus and family, and the monophyly of these groups was rejected based on parametric bootstrap analysis. As C. fasciatus is the nominal species for the genus and family, widespread taxonomic reassignment is implicated for the remaining 12 and 17 members of these groups, respectively. As these 17 cheilodactylids are not genetically or morphologically distinct from the latrids, it is proposed that the Latridae should be expanded to encompass them. The inferred relationships among those Cheilodactylus requiring generic reassignment were largely unresolved, and hence few recommendations can be made regarding their placement. Divergence time estimates indicate that chance oceanic dispersal subsequent to Gondwanan fragmentation best explains the Southern Hemisphere radiation of cheilodactylids.

Lack of genetic divergence found with microsatellite DNA markers in the tarakihi Nemadactylus macropterus

Abstract Three classes of molecular markers are commonly employed during population genetic studies of marine taxa: allozymes, mitochondrial DNA (mtDNA), and microsatellite DNA. These markers differ in their levels of polymorphism, and the ease and cost of their application. Nemadactylus macropterus is a commercially important marine fish from New Zealand and southern Australia that has been the subject of genetic (allozyme, mtDNA) and non‐genetic (otolith microchemistry, larval advection) studies of stock structure. We collected microsatellite DNA data from this species to compare the utility of these molecular markers with those genetic methods previously applied to N. macropterus. Microsatellites did not indicate significant divergence among Australian samples, or between Australian and New Zealand samples. The latter is incongruent with the allozyme and mtDNA studies, and it is suggested that allelic homoplasy has hindered the resolution of population structure when using microsatellites.

Description and genetic identification of the early life-stages of Notolabrus fucicola and N. tetricus from Tasmanian waters, Australia, with notes on their newly-settled juveniles

Abstract The early life‐stages of Notolabrus fucicola and N. tetricus are described and illustrated. Developmental stages examined included eggs and yolk‐sac larvae reared in aquaria and post‐settlement juveniles collected from artificial habitats in the coastal waters of eastern Tasmania, Australia. Larvae were similar to other labrids previously described. Species‐specific characters were only evident after settlement, and with the development of scales at c. 15 mm standard length. A molecular assay, based on restriction fragment length polymorphism (RFLP), enabled the discrimination of all five of the closely‐related wrasses in the genera Notolabrus, Pseudolabrus, Dotalabrus, and Pictilabrus found on the east coast of Tasmania. This study constitutes the first description of the early life‐stages of Notolabrus spp. from temperate Australia.

Genetic diversity and breed comparison of carcass traits in Tasmanian Corriedale and East-Friesian sheep by RAPD markers

All organisms are subject to mutations as a result of normal cellular operations or interactions with the environment, leading to genetic variation (polymorphism). In conjunction with selection and genetic drift, there arises genetic variation within and among individuals and species. For this variation to be useful to geneticists, it must be heritable and discernable whether as a recognisable phenotypic variation or as a genetic mutation distinguishable through molecular techniques. PCR amplification and gel electrophoresis resolution of products using RAPD primer A2 shows polymorphism of up to 5 bands was evident. It also demonstrates that at the molecular level, there are banding differences that can be picked up between crossbred progeny sired by rams with high genetic merit for growth or muscle.Fat depth at the GR and C sites was significantly (P<0.05) influenced by level of nutrition and nutrition level x siretype interaction in that fat depths were greater in crossbred lambs fed at high levels of nutrition than those fed low nutrition levels. Lambs selected for growth and fed high level of nutrition produced carcasses with the least KNIFE GR fat depth of 11.4mm, a significant reduction from 18.1mm in the control group fed low level nutrition.RAPD marker assays are based on polymerase chain reaction amplification of random segments of the DNA with an identical pair of primers 8-10 bp in length consisting of arbitrary nucleotide sequence. Genetic variation and divergence within and between breeds of interest are assessed by the presence or absence of each product which is dictated by the DNA sequence at each locus. The power to detect polymorphisms is very high given that 5-20 bands can be produced using a given primer pair and multiple sets of random primers can be used to scan the entire genome for differential RAPD bands. RAPD has several advantages over other molecular markers because it can be used with uncharacterised genomes without prior knowledge of nucleotide sequence information and can be applied to problems in which only small quantities of DNA are available. It is also efficient and inexpensive.At the same slaughter weight and body condition score, Corriedales had significantly (P 0.09).

RAPD marker variation in meat quality traits of Poll Dorset second-cross lambs selected for muscle or growth

All organisms are subject to mutations as a result of normal cellular operations or interactions with the environment, leading to genetic variation (polymorphism). In conjunction with selection and genetic drift, there arises genetic variation within and among individuals and species. For this variation to be useful to geneticists, it must be heritable and discernable whether as a recognisable phenotypic variation or as a genetic mutation distinguishable through molecular techniques. PCR amplification and gel electrophoresis resolution of products using RAPD primer A2 shows polymorphism of up to 5 bands was evident. It also demonstrates that at the molecular level, there are banding differences that can be picked up between crossbred progeny sired by rams with high genetic merit for growth or muscle.Fat depth at the GR and C sites was significantly (P<0.05) influenced by level of nutrition and nutrition level x siretype interaction in that fat depths were greater in crossbred lambs fed at high levels of nutrition than those fed low nutrition levels. Lambs selected for growth and fed high level of nutrition produced carcasses with the least KNIFE GR fat depth of 11.4mm, a significant reduction from 18.1mm in the control group fed low level nutrition.RAPD marker assays are based on polymerase chain reaction amplification of random segments of the DNA with an identical pair of primers 8-10 bp in length consisting of arbitrary nucleotide sequence. Genetic variation and divergence within and between breeds of interest are assessed by the presence or absence of each product which is dictated by the DNA sequence at each locus. The power to detect polymorphisms is very high given that 5-20 bands can be produced using a given primer pair and multiple sets of random primers can be used to scan the entire genome for differential RAPD bands. RAPD has several advantages over other molecular markers because it can be used with uncharacterised genomes without prior knowledge of nucleotide sequence information and can be applied to problems in which only small quantities of DNA are available. It is also efficient and inexpensive.At the same slaughter weight and body condition score, Corriedales had significantly (P 0.09).