Data from: Age-dependent trajectories differ between within-pair and extra-pair paternity success

Reproductive success is associated with age in many taxa, increasing in early life followed by reproductive senescence. In socially monogamous, but genetically polygamous species, this generates the interesting possibility of differential trajectories of within-pair and extra-pair siring success with age in males. We investigate these relationships simultaneously using within-individual analyses with 13 years of data from an insular house sparrow (Passer domesticus) population. As expected, we found that both within- and extra-pair paternity success increased with age, followed by a senescence-like decline. However, the age trajectories of within- and extra-pair paternity successes differed significantly, with the extra-pair paternity success increasing faster, albeit non-significantly so, in early life, and showing a delayed decline by 1.5 years on average later in life compared to within-pair paternity success. These different trajectories indicate that the two alternative mating tactics should have age-dependent payoffs. Males may partition their reproductive effort between within- and extra-pair matings depending on their current age in order to reap the maximal combined benefit from both strategies. The interplay between these mating strategies and age-specific mortality may explain the variation in rates of extra-pair paternity observed within and between-species.诸多生物类群的繁殖成功率均与年龄相关：在生命早期随年龄增长而提升，随后出现繁殖衰老（reproductive senescence）现象。在社会婚配制度为一夫一妻制但遗传婚配制度为多配制的物种中，这一规律催生了一个有趣的可能性：雄性个体的婚内父系繁育成功率与配对外父系繁育成功率会随年龄呈现截然不同的变化轨迹。本研究基于一座岛屿上家雀（Passer domesticus）种群长达13年的监测数据，采用个体内分析方法，同时探究了上述两类父系繁育成功率与年龄的关联。正如预期，我们发现婚内与配对外父系成功率均随年龄增长而提升，随后出现类似衰老的下降趋势。但二者随年龄的变化轨迹存在显著差异：配对外父系成功率在生命早期的增长速度更快（虽未达到统计学显著性），且相较于婚内父系成功率，其衰退时间平均延迟了1.5年。这种轨迹差异表明，两种可选交配策略（婚内与配对外交配）应存在年龄依赖性的收益回报。雄性个体可根据自身当前年龄，将繁殖投入分配至婚内与配对外交配中，以从两种策略中获取最大化的综合收益。这些交配策略与年龄特异性死亡率之间的相互作用，或可解释物种内部及物种间观察到的配对外父系比例差异。