An integrated linkage map of perlemoen (haliotis midae)

[摘要] ENGLISH ABSTRACT: Haliotis midae, or Perlemoen, is the only cultured species of abalone in South Africa and isunder great international demand. This species is considered endangered, makingsustainable farming practises and law enforcement against poaching essential formaintaining wild stocks. A limited amount of broodstock animals are provided to each farmfrom which thousands of offspring are grown and exported. The prevention of inbreedingand preservation of genetic diversity within farmed stocks is necessary for futuresustainable farming and production of genetically stable offspring. Further research intothe genetic dynamics of Perlemoen will provide the knowledge for advanced managementprograms for optimal farming practises and essentially sustainable production. This studyfocuses on genetic linkage map development with the intention of future identification ofmarkers associated with genes of economic importance, such as growth rate. Identificationof markers linked to genes responsible for such phenotypic traits will ultimately allowfarming practises to select naturally genetically superior animals for breeding, therebyenhancing production.For the construction of a genetic linkage map of H. midae, microsatellite markers weredeveloped using two strategies: FIASCO and screening of next generation sequence-bysynthesiscontig data. The FIASCO-derived markers were characterised by genotypescreening in 32 individuals from a full-sib family and analysed using Mendeliansegregation expectations. The Illumina-derived markers were characterised by genotypescreening in 32 individuals from wild populations and analysed against Hardy-Weinbergexpectations. Forty four microsatellite-family combinations were obtained from FIASCO ofwhich 28 provided informative genotype results (32% success). Twenty two markers weredeveloped from sequence-by-synthesis screening. Fourteen provided reliable genotypes(37%) and six conformed to Hardy-Weinberg expectations.These markers were used, in addition to 156 previously developed markers, to developsex-specific and sex-average linkage maps in two full-sib families consisting ofapproximately 100 offspring each. One hundred and six polymorphic loci were used forlinkage analysis (LOD>3) in both families. The number of linkage groups obtained fromsex-specific maps ranged from 13-16. The average genome length ranged from 500 cM to800 cM with an average marker spacing of 10 cM. The sex-average linkage map provided 18 linkage groups with an average genome length calculation of 1800 cM and averagemarker spacing of approximately 13 cM.The linkage maps created in this study are preliminary but provide a stepping stonetowards a high density map incorporating high throughput markers. This also provides abase for QTL mapping studies, in which phenotypic traits of interest can be identified andassociated to specific locations in the H. midae genome for marker-assisted selection.

[发布机构] Stellenbosch University