Browsing by Author "Maduna, Simo N."
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- ItemMicrosatellite cross-species amplification and utility in southern African elasmobranchs : a valuable resource for fisheries management and conservation(BMC Research Notes, 2014) Maduna, Simo N.; Rossouw, Charne; Roodt-Wilding, Rouvay; Bester-Van der Merwe, Aletta E.Background: Similarly to the rest of the world, southern Africa’s diverse chondrichthyan fauna is currently experiencing high fishing pressures from direct and non-direct fisheries to satisfy market demands for shark products such as fins and meat. In this study, the development of microsatellite markers through cross-species amplification of primer sets previously developed for closely related species is reported as an alternative approach to de novo marker development. This included the design of four microsatellite multiplex assays and their cross-species utility in genetic diversity analysis of southern African elasmobranchs. As this study forms part of a larger project on the development of genetic resources for commercially important and endemic southern African species, Mustelus mustelus was used as a candidate species for testing these multiplex assays in down-stream applications. Results Thirty five microsatellite primer sets previously developed for five elasmobranch species were selected from literature for testing cross-species amplification in 16 elasmobranch species occurring in southern Africa. Cross-species amplification success rates ranged from 28.6%-71.4%. From the successfully amplified microsatellites, 22 loci were selected and evaluated for levels of polymorphism, and four multiplex assays comprising of the 22 microsatellites were successfully constructed, optimised and characterised in a panel of 87 Mustelus mustelus individuals. A total of 125 alleles were observed across all loci, with the number of alleles ranging from 3–12 alleles. Cross-species amplification of the four optimised multiplex assays was further tested on 11 commercially important and endemic southern African elasmobranch species. Percentage of polymorphism ranged from 31.8%-95.5% in these species with polymorphic information content decreasing exponentially with evolutionary distance from the source species. Conclusions Cross-species amplification of the 35 microsatellites proved to be a time- and cost-effective approach to marker development in elasmobranchs and enabled the construction of four novel multiplex assays for characterising genetic diversity in a number of southern African elasmobranch species. This study successfully demonstrated the usefulness of these markers in down-stream applications such as genetic diversity assessment and species identification which could potentially aid in a more integrative, multidisciplinary approach to management and conservation of commercially important cosmopolitan and endemic elasmobranch species occurring in southern Africa.
- ItemSpecies identification and comparative population genetics of four coastal houndsharks based on novel NGS-mined microsatellites(Wiley Open Access, 2017) Maduna, Simo N.; Rossouw, Charne; Da Silva, Charlene; Soekoe, Michelle; Bester-Van Der Merwe, Aletta E.The common smooth-hound (Mustelus mustelus) is the topmost bio-economically and recreationally important shark species in southern Africa, western Africa, and Mediterranean Sea. Here, we used the Illumina HiSeq™ 2000 next-generation sequencing (NGS) technology to develop novel microsatellite markers for Mustelus mustelus. Two microsatellite multiplex panels were constructed from 11 polymorphic loci and characterized in two populations of Mustelus mustelus representative of its South African distribution. The markers were then tested for cross-species utility in Galeorhinus galeus, Mustelus palumbes, and Triakis megalopterus, three other demersal coastal sharks also subjected to recreational and/or commercial fishery pressures in South Africa. We assessed genetic diversity (NA, AR, HO, HE, and PIC) and differentiation (FST and Dest) for each species and also examined the potential use of these markers in species assignment. In each of the four species, all 11 microsatellites were variable with up to a mean NA of 8, AR up to 7.5, HE and PIC as high as 0.842. We were able to reject genetic homogeneity for all species investigated here except for T. megalopterus. We found that the panel of the microsatellite markers developed in this study could discriminate between the study species, particularly for those that are morphologically very similar. Our study provides molecular tools to address ecological and evolutionary questions vital to the conservation and management of these locally and globally exploited shark species.