title: A polygenic hypothesis for sex determination in the European sea bass Dicentrarchus labrax.
abstract: Polygenic sex determination, although suspected in several species, is thought to be evolutionarily unstable and has been proven in very few cases. In the European sea bass, temperature is known to influence the sex ratio. We set up a factorial mating, producing 5.893 individuals from 253 full-sib families, all reared in a single batch to avoid any between-families environmental effects. The proportion of females in the offspring was 18.3%, with a large variation between families. Interpreting sex as a threshold trait, the heritability estimate was 0.62 +/- 0.12. The observed distribution of family sex ratios was in accordance with a polygenic model or with a four-sex-factors system with environmental variance and could not be explained by any genetic model without environmental variance. We showed that there was a positive genetic correlation between weight and sex (r(A) = 0.50 +/- 0.09), apart from the phenotypic sex dimorphism in favor of females. This supports the hypothesis that a minimum size is required for sea bass juveniles to differentiate as females. An evolution of sex ratio by frequency-dependent selection is expected during the domestication process of Dicentrarchus labrax populations, raising concern about the release of such fish in the wild.
authors: INRA, UR544 Génétique des Poissons, F-78350 Jouy en Josas, France. marc.vandeputte@jouy.inra.fr
authors: Marc
authors: M
authors: Vandeputte
authors: Mathilde
authors: M
authors: Dupont-Nivet
authors: Hervé
authors: H
authors: Chavanne
authors: Béatrice
authors: B
authors: Chatain
mesh_terms: D000818:Animals; D001267:Atlantic Ocean; D001492:Bass / Q000235:genetics*; D003433:Crosses, Genetic; D004777:Environment; D019143:Evolution, Molecular; D005260:Female; D005602:France; D008297:Male; D009865:Oocytes / Q000502:physiology; D012732:Sex Determination Analysis / Q000379:methods*; D019849:Sex Determination Processes; D012744:Sex Ratio; D013094:Spermatozoa / Q000502:physiology