Identification of naturally occurring hybrids between two overexploited sciaenid species along the South African coast

Hybridization between fish species can play a significant role in evolutionary processes and can influence management and conservation planning, however, this phenomenon has been widely understudied, especially in marine organisms. The distribution limits of two sciaenid species (silver kob, Argyrosomus inodorus, and dusky kob, A. japonicus) partly overlap along the South African coast, where both species have undergone severe depletion due to overfishing. Following the identification of a number of possible cases of species misidentification or hybridization (21 out of 422 individuals), nuclear and mitochondrial DNA data (12 microsatellite loci and 562 bp of the COI gene) were analysed to investigate the genetic composition of these individuals. Results indicated a field-based species misidentification rate of approximately 2.8% and a rate of natural hybridization of 0.7%. Interestingly, all hybrid fish resulted from first-generation (F1) hybridization events, which occurred exclusively between silver kob females and dusky kob males. Whether hybridization is the result of natural events (such as secondary contact following a shift in distribution range), or anthropogenic activities (size-selective pressure due to overfishing), these findings have important implications for critical recovery and future management of these species in the wild.DAFF (South Africa)http://www.elsevier.com/locate/ympevhb201

Transcriptome characterization of the South African abalone Haliotis midae using sequencing-by-synthesis

<p>Abstract</p> <p>Background</p> <p>Worldwide, the genus <it>Haliotis </it>is represented by 56 extant species and several of these are commercially cultured. Among the six abalone species found in South Africa, <it>Haliotis midae </it>is the only aquacultured species. Despite its economic importance, genomic sequence resources for <it>H. midae</it>, and for abalone in general, are still scarce. Next generation sequencing technologies provide a fast and efficient tool to generate large sequence collections that can be used to characterize the transcriptome and identify expressed genes associated with economically important traits like growth and disease resistance.</p> <p>Results</p> <p>More than 25 million short reads generated by the Illumina Genome Analyzer were <it>de novo </it>assembled in 22,761 contigs with an average size of 260 bp. With a stringent <it>E</it>-value threshold of 10^-10, 3,841 contigs (16.8%) had a BLAST homologous match against the Genbank non-redundant (NR) protein database. Most of these sequences were annotated using the gene ontology (GO) and eukaryotic orthologous groups of proteins (KOG) databases and assigned to various functional categories. According to annotation results, many gene families involved in immune response were identified. Thousands of simple sequence repeats (SSR) and single nucleotide polymorphisms (SNP) were detected. Setting stringent parameters to ensure a high probability of amplification, 420 primer pairs in 181 contigs containing SSR loci were designed.</p> <p>Conclusion</p> <p>This data represents the most comprehensive genomic resource for the South African abalone <it>H. midae </it>to date. The amount of assembled sequences demonstrated the utility of the Illumina sequencing technology in the transcriptome characterization of a non-model species. It allowed the development of several markers and the identification of promising candidate genes for future studies on population and functional genomics in <it>H. midae </it>and in other abalone species.</p

Non-destructive sampling of juvenile abalone using epipodial tentacles and mucus: method and application

Good-quality biological material is needed to obtain intact deoxyribonucleic acid (DNA) for use in molecular techniques such as the polymerase chain reaction (PCR). Non-destructive sampling protocols of juvenile abalone Haliotis midae (7–15 months old) were tested in order to collect material for DNA extraction. DNA was successfully extracted from epipodial tentacles and mucus samples. PCR results confirmed the good quality of the DNA and the reliability of the method. Keywords: abalone, DNA extraction, DNA quality, epipodial tentacles, mucus, non-destructive sampling, PCRAfrican Journal of Marine Science 2006, 28(3&4): 719–72

Bioinformatic survey of haliotis midae microsatellites reveals a non-random distribution of repeat motifs

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Development and application of genetic markers to aid modern breeding programmes of depleted South African dusky kob.

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Selection and sea snails: the South African story.

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Molecular markers to assist the South African abalone industry

CITATION: Roodt-Wilding, R. & Slabbert, R. 2006. Molecular markers to assist the South African abalone industry. South African Journal of Science, 102(3-4):99-102.The original publication is available at https://journals.co.zaHALIOTIS MIDAE (PERLEMOEN) IS THE ONLY southern African species of abalone to be commercially exploited. Commercial farms are currently producing 750 tons per annum, making this an economically viable enterprise. Increasing world demand and dwindling natural populations have, however, necessitated the adoption of genetic management practices on South African abalone farms to remain sustainable. This can be done by means of DNA markers, which are employed to investigate various phenomena from genetic diversity, parentage and broodstock contributions to linkage mapping and marker-assisted selection for genetic enhancement of the commercial species. The use of microsatellite markers for various abalone aquaculture applications is highlighted in this review.https://journals.co.za/content/sajsci/102/3-4/EJC96525Publisher's versio

Investigation of the autofluorescence of various abalone (<I>Haliotis midae</I>) tissues and the implications for future use of fluorescent molecules

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Phylogenetic relationships in southern African chloridoid grasses (Poaceae) based on nuclear and chloroplast sequence data

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Reproductive histology of cultured <I>Haliotis Midae</I> (Linnaeus, 1758) and preliminary evaluation of maturation

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