Data from: Lifetime reproductive success, selection on lifespan and multiple sexual ornaments in male European barn swallows

Natural and sexual selection arise when individual fitness varies according to focal traits. Extra-pair paternities (EPPs) can affect the intensity of selection by influencing variance in fitness among individuals. Studies of selection require that individual fitness is estimated using proxies of lifetime reproductive success (LRS). However, estimating LRS is difficult in large, open populations where EPPs cause reallocation of biological paternity. Here we used extensive field sampling to estimate LRS in a population of barn swallows (Hirundo rustica) to estimate selection on lifespan and ornamental traits of males. We found selection on lifespan mediated both by within- and extra-pair fertilization success and selection on tail length mediated by within- but not extra-pair fertilization success. In addition, we found selection on tail white spots via extra-pair fertilization success after controlling for selection on other traits. These results were not confounded by factors that hamper studies of LRS, including non-exhaustive sampling of offspring and biased sampling of males. Hence, natural and sexual selection mediated by LRS operates on lifespan, tail length and size of the tail white spots in barn swallows.

当个体适合度（fitness）随目标性状发生变化时，自然选择与性选择便会产生。配偶外父权（extra-pair paternities, EPPs）可通过改变个体间适合度的变异程度，影响选择作用的强度。相关选择研究需借助终生繁殖成功率（lifetime reproductive success, LRS）的替代指标，对个体适合度进行估算。然而，在配偶外父权会导致生物学父权重新分配的大型开放种群中，估算终生繁殖成功率颇具难度。本研究通过大规模野外采样，对家燕（Hirundo rustica）种群的终生繁殖成功率进行估算，以此分析雄性个体寿命与装饰性性状所受的选择作用。研究结果显示，雄性寿命所受的选择作用同时受婚内与配偶外受精成功率的介导，而尾长所受的选择作用仅由婚内受精成功率介导，与配偶外受精成功率无关。此外，在控制其他性状所受选择作用的影响后，我们发现尾羽白色斑点所受的选择作用可通过配偶外受精成功率进行介导。本研究结果并未受到干扰终生繁殖成功率研究的各类因素的混淆，例如子代采样不全面以及雄性个体采样存在偏差等。综上，由终生繁殖成功率介导的自然选择与性选择，可作用于家燕的寿命、尾长以及尾羽白色斑点大小这三个性状。