Abstract
BackgroundA key developmental transformation in the life of all vertebrates is the transition to sexual maturity, whereby individuals are capable of reproducing for the first time. In the farming of Atlantic salmon, early maturation prior to harvest size has serious negative production impacts.ResultsWe report genome wide association studies (GWAS) using fish measured for sexual maturation in freshwater or the marine environment. Genotypic data from a custom 50 K single nucleotide polymorphism (SNP) array was used to identify 13 significantly associated SNP for freshwater maturation with the most strongly associated on chromosomes 10 and 11. A higher number of associations (48) were detected for marine maturation, and the two peak loci were found to be the same for both traits. The number and broad distribution of GWAS hits confirmed a highly polygenetic nature, and GWAS performed separately within males and females revealed sex specific genetic behaviour for loci co-located with positional candidate genes phosphatidylinositol-binding clathrin assembly protein-like (picalm) and membrane-associated guanylate kinase, WW and PDZ domain-containing protein 2 (magi2).ConclusionsThe results extend earlier work and have implications for future applied breeding strategies to delay maturation in this important aquaculture species.
Highlights
A key developmental transformation in the life of all vertebrates is the transition to sexual maturity, whereby individuals are capable of reproducing for the first time
Study population and two maturation traits The study population is from the Salmon Enterprises of Tasmania (SALTAS) selective breeding program, which offers the opportunity to exploit large pedigrees and progeny trait data to perform genome wide association studies (GWAS)
Maturation was assessed as two traits due to the life cycle of Atlantic salmon and the associated breeding program design (Additional file 3)
Summary
A key developmental transformation in the life of all vertebrates is the transition to sexual maturity, whereby individuals are capable of reproducing for the first time. The development of sexual maturation in Atlantic salmon (Salmo salar) is a complex process informed by both genetic and environmental cues. It is highly variable, with extremes in age and size at maturation the result of adaptation to maximise fitness and reproductive success [1]. The consequence is an elevated proportion of farmed animals entering maturation younger and at weights below harvest size, generating substantial production inefficiency. This can be partly addressed through modified management practise and selective breeding for delayed maturation, the positive correlation with growth makes uncoupling positive and negative production impacts challenging.
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