The risk of brood parasitism does not affect levels of extra-pair paternity in a cuckoo host

In socially monogamous bird species, extra-pair paternity is common, but its level varies considerably within and among species. For hosts of brood parasites, the risk of brood parasitism may influence the costs of engaging in extra-pair copulations (e.g., leaving the nest undefended) and the benefits of having extra-pair young (e.g., spreading the risk of nest predation). However, whether brood parasitism risk affects extra-pair behavior in host species has rarely been tested. We investigated whether variation in the risk of brood parasitism affected levels of extra-pair paternity in Daurian redstarts, a socially monogamous passerine. As a common host of the common cuckoo, the redstart is unique in that its first clutch of the year takes place before the arrival of cuckoos. As a consequence, redstarts experience large seasonal variation in cuckoo parasitism risk, with no parasitism in the first egg-laying period and a high risk in the second period. We genotyped 995 nestlings (and unha..., , , README The key columns for dataset year = study year nest_id = nest identity clutch = egg-laying period (first/second) plot = subplot of the study site treatment = manipulation of perceived brood parasitism risk (cuckoo/control); 'NA' indicates nest from 2018, when we did not conduct the manipulation clutch_size = clutch size; 'NA' means the clutch size is unknown typed_young = number of offspring genotyped epy_yn = whether the brood includes extra-pair young or not epp_loss = number of extra-pair young in the brood prop_epy = proportion of extra-pair young in the brood在社会一夫一妻制鸟类类群中，窝外父权（extra-pair paternity）现象较为普遍，但不同物种间以及同一物种内部的窝外父权水平差异显著。对于巢寄生（brood parasitism）的宿主物种而言，巢寄生风险可能会影响其进行窝外配偶交配的成本（例如，疏于守卫巢穴），以及拥有窝外子代的收益（例如，分散巢被捕食的风险）。然而，巢寄生风险是否会影响宿主物种的窝外行为，目前鲜有相关研究验证。本研究以社会一夫一妻制的雀形目鸟类达乌里红尾鸲（Daurian redstart）为研究对象，探讨巢寄生风险的变化是否会影响其窝外父权水平。作为普通杜鹃（common cuckoo）的常见宿主，达乌里红尾鸲的独特之处在于其年度第一窝产卵发生在杜鹃抵达栖息地之前。因此，红尾鸲面临的杜鹃巢寄生风险存在显著的季节差异：首个产卵期无寄生风险，而第二产卵期则面临较高的寄生风险。我们对995只雏鸟进行了基因分型（内容未完整显示：and unha..., , , README）。 ### 数据集核心字段说明 - year：研究年份 - nest_id：巢唯一标识 - clutch：产卵批次（分为第一、第二批次） - plot：研究样地的亚样区 - treatment：巢寄生风险感知处理组，分为杜鹃组、对照组；"NA"代表2018年的巢，该年度未开展处理实验 - clutch_size：窝卵数；"NA"表示窝卵数未知 - typed_young：完成基因分型的子代个体数 - epy_yn：该窝是否包含窝外子代 - epp_loss：该窝内窝外子代的数量 - prop_epy：该窝内窝外子代的占比