In species with complex life cycles, life history theory predicts that fitness is affected by conditions encountered in previous life history stages. Here, we use a four-year pedigree to investigate if time spent in two distinct life history stages has sex-specific reproductive fitness consequences in anadromous Atlantic salmon (Salmo salar). We determined the amount of years spent in fresh water as juveniles (freshwater age, FW, measured in years), and years spent in the marine environment as adults (sea age, SW, measured in sea winters) on 264 sexually mature adults collected on a river spawning ground. We then estimated reproductive fitness as the number of offspring (reproductive success) and the number of mates (mating success) using genetic parentage analysis (>5000 offspring). Sea age is significantly and positively correlated with reproductive and mating success of both sexes whereby older and larger individuals gained the highest reproductive fitness benefits (females: 62.2% increase in offspring/SW and 34.8% increase in mate number/SW; males: 201.9% offspring/SW and 60.3% mates/SW). Younger freshwater age was significantly related to older sea age and thus increased reproductive fitness, but only among females (females: -33.9% offspring/FW and -32.4% mates/FW). This result implies that females can obtain higher reproductive fitness by transitioning to the marine environment earlier. In contrast, male mating and reproductive success was unaffected by freshwater age and more males returned at a younger age than females despite the reproductive fitness advantage of later sea age maturation. Our results show that the timing of transitions between juvenile and adult phases has a sex-specific consequence on female reproductive fitness, demonstrating a life-history trade-off between maturation and reproduction in wild Atlantic salmon.

中文翻译：

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在不同的生活史阶段中度过的时间对野生大西洋鲑鱼的生殖适应具有特定性别的影响。

在具有复杂生命周期的物种中，生命史理论预测，适应性会受到先前生命史阶段所遇到条件的影响。在这里，我们使用四年的血统书来研究在两个不同的生活史阶段中所花费的时间是否对无性大西洋鲑（Salmo salar）产生了特定性别的生殖适应性后果。我们确定了在264位经性成熟的成年人中，以淡水作为幼体的淡水年数（淡水年龄，FW，以年为单位），以成年人为水生环境（海洋年龄，SW，以海冬为单位）。河流产卵场。然后，我们通过遗传亲缘关系分析（> 5000个后代），以子代数（生殖成功）和伴侣数（交配成功）来估算生殖适应度。海水年龄与两性生殖和交配成功显着正相关，因此年龄较大和较大的个体获得最高的生殖健康益处（女性：后代/性交增加62.2％，伴侣/性交增加34.8％；男性：201.9％后代/西南和60.3％的同伴/西南）。较淡的淡水年龄与较高的海水年龄显着相关，从而增加了生殖健康，但仅在女性中（女性：后代/公仔为-33.9％，伴侣/公仔为-32.4％）。这一结果表明，雌性可以通过更早地过渡到海洋环境而获得更高的生殖适应性。相反，淡水年龄不会影响男性的交配和繁殖成功，尽管后期海龄成熟具有生殖健康优势，但男性比女性更年轻地返回。