Data from: Song performance is a condition-dependent dynamic trait honestly indicating the quality of paternal care in the Bull-headed Shrike

The good parent hypothesis in sexual selection predicts that if females can increase their fitness by mating with males who provide high-quality parental care, then female preferences for male phenotypes honestly indicating the quality of paternal care will evolve. In order to test this hypothesis, we investigated correlations between male song, the timing of pair formation of males, male feeding rate, and reproductive success, in the Bull-headed Shrike Lanius bucephalus (an altricial oscine passerine with biparental care). Analysis revealed that although the timing of pair formation was not correlated with most song characteristics (e.g. repertoire size), male morphological traits (e.g. tail length), or male territory size, it was negatively correlated with male singing tempo (i.e. the number of notes uttered per second). Those males that sang at higher speeds were in better body condition (i.e. body mass standardized by tarsus length³ was higher), fed their chicks frequently during the nestling period, and raised heavy chicks. These results show that in the Bull-headed Shrike male singing tempo is a condition-dependent dynamic trait honestly indicating the quality of paternal care, and strongly supports the good parent hypothesis.

性选择中的好父母假说预测，若雌性通过与能提供高质量育幼照料的雄性交配可提升自身适合度，那么雌性对能够诚实反映父育质量的雄性表型的偏好便会演化形成。为验证该假说，我们对红尾伯劳（Lanius bucephalus，一种实行双亲育幼的晚成鸣禽）的雄性鸣唱、雄性配对时机、雄性育雏频率与繁殖成功率之间的相关性展开了研究。分析结果显示，尽管雄性配对时机与多数鸣唱特征（如鸣唱曲目量）、雄性形态特征（如尾长）及雄性领地面积均无相关性，但它与雄性鸣唱速度（即每秒发出的鸣唱音节数）呈负相关关系。那些鸣唱速度更快的雄性，身体状况更佳（即经跗跖长度三次方标准化后的体重更高），在雏鸟育雏期会更频繁地给雏鸟喂食，并能抚育出体重更大的雏鸟。上述结果表明，在红尾伯劳中，雄性鸣唱速度是一种依赖于身体状况的动态特征，能够诚实反映父育质量，从而为好父母假说提供了强有力的支持。