Despite the key role that sex-determination plays in evolutionary processes, it is still poorly understood in many species. In salmonids, which are among the best studied fishes, the master sex-determining gene sexually dimorphic on the Y-chromosome (sdY) has been identified. However, sdY displays unexplained discordance to the phenotypic sex, with a variable frequency of phenotypic females being reported as genetic males. Multiple sex determining loci in Atlantic salmon have also been reported, possibly as a result of recent transposition events in this species. We hypothesized the existence of an autosomal copy of sdY, causing apparent discordance between phenotypic and genetic sex, that is transmitted in accordance with autosomal inheritance. To test this, we developed a qPCR methodology to detect the total number of sdY copies present in the genome. Based on the observed phenotype/genotype frequencies and linkage analysis among 2,025 offspring from 64 pedigree-controlled families of accurately phenotyped Atlantic salmon, we identified both males and females carrying one or two autosomal copies of sdY in addition to the Y-specific copy present in males. Patterns across families were highly consistent with autosomal inheritance. These autosomal sdY copies appear to have lost the ability to function as a sex determining gene and were only occasionally assigned to the actual sex chromosome in any of the affected families.

尽管性别决定在进化过程中起着关键作用，但在许多物种中对它的了解仍然很少。在研究最多的鱼类之一的鲑鱼中，主要的决定性别的基因在Y染色体上呈​​性别二态性（d）已被识别。然而，d表现出对表型性别的无法解释的不一致，据报道有可变频率的表型女性是遗传男性。也已经报道了大西洋鲑鱼中多个决定性别的基因座，这可能是由于该物种最近发生的转座事件所致。我们假设存在一个常染色体拷贝的d，导致表型和遗传性别之间出现明显的不一致，这种不一致是根据常染色体遗传而传播的。为了测试这一点，我们开发了一种qPCR方法来检测d复制存在于基因组中。根据观察到的表型/基因型频率以及来自64个家系对照家庭的精确表型大西洋鲑的2025个后代之间的连锁分析，我们确定了携带一或两个常染色体拷贝的大西洋鲑的雄性和雌性。d除了男性中存在的Y特异拷贝。家庭间的模式与常染色体遗传高度一致。这些常染色体d 拷贝似乎失去了作为性别决定基因的功能，并且在任何受影响的家庭中，偶而仅被偶然分配给实际的性染色体。