Abstract
BackgroundEuropean sea bass (Dicentrarchus labrax) is one of the most important farmed species in Mediterranean aquaculture. The observed sexual growth and maturity dimorphism in favour of females adds value towards deciphering the sex determination system of this species. Current knowledge indicates the existence of a polygenic sex determining determination system that interacts with temperature. This was explored by restriction-site associated DNA (RAD) marker analysis in a test panel of 175 offspring that originated from a factorial cross between two dams and four sires from a single full-sib family.ResultsThe first high-density single nucleotide polymorphism (SNP) based linkage map for sea bass was constructed, consisting of 6706 SNPs on 24 linkage groups. Indications for putative sex-determining QTL (quantitative trait loci) that were significant at the genome-wide threshold were detected on linkage groups 6, 11 and 18 to 21, although a genome-wide association study (GWAS) did not identify individual significant SNPs at a genome-wide threshold. A preliminary genomic prediction approach that tested the efficiency of SNP-based selection for female sea bass showed a slight advantage compared to traditional pedigree-based selection. However, when the same models were tested on the same animals for selection for greater length, a clear advantage of the SNP-based selection was observed.ConclusionsOverall, the results of this study provide additional support to the polygenic sex determination hypothesis in sea bass. In addition, identification of sex-ratio QTL may provide new opportunities for sex-ratio control in sea bass.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-015-0148-y) contains supplementary material, which is available to authorized users.
Highlights
European sea bass (Dicentrarchus labrax) is one of the most important farmed species in Mediterranean aquaculture
In order to maximise the number of informative single nucleotide polymorphism (SNP) and minimise the amount of missing or erroneous data, we used the restriction-site associated DNA (RAD)-tags that were retrieved in at least 75 % of the samples in each family, and that carried only one or two SNPs
We present the first high-density linkage map of D. labrax based on 6706 SNPs (2676 unique positions)
Summary
European sea bass (Dicentrarchus labrax) is one of the most important farmed species in Mediterranean aquaculture. Current knowledge indicates the existence of a polygenic sex determining determination system that interacts with temperature This was explored by restriction-site associated DNA (RAD) marker analysis in a test panel of 175 offspring that originated from a factorial cross between two dams and four sires from a single full-sib family. Males tend to grow more slowly than females and lower body weights at harvest time (up to 40 % less) have been reported compared to those of identical cohorts of females [7, 8] This dimorphism can be interpreted as an advantage to produce large females in a mass-spawning species, as observed in the Atlantic silverside Menidia menidia [9]
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