Data from: Double decomposition: decomposing the variance in subcomponents of male extra-pair reproductive success

Abstract1. Extra-pair reproductive success (EPRS) is a key component of male fitness in socially monogamous systems and could cause selection on female extra-pair reproduction if extra-pair offspring (EPO) inherit high value for EPRS from their successful extra-pair fathers. However, EPRS is itself a composite trait that can be fully decomposed into subcomponents of variation, each of which can be further decomposed into genetic and environmental variances. However, such decompositions have not been implemented in wild populations, impeding evolutionary inference. 2. We first show that EPRS can be decomposed into the product of three life-history subcomponents: the number of broods available to a focal male to sire EPO, the male's probability of siring an EPO in an available brood and the number of offspring in available broods. This decomposition of EPRS facilitates estimation from field data because all subcomponents can be quantified from paternity data without need to quantify extra-pair matings. Our decomposition also highlights that the number of available broods, and hence population structure and demography, might contribute substantially to variance in male EPRS and fitness. 3. We then used 20 years of complete genetic paternity and pedigree data from wild song sparrows (Melospiza melodia) to partition variance in each of the three subcomponents of EPRS, and thereby estimate their additive genetic variance and heritability conditioned on effects of male coefficient of inbreeding, age and social status. 4. All three subcomponents of EPRS showed some degree of within-male repeatability, reflecting combined permanent environmental and genetic effects. Number of available broods and offspring per brood showed low additive genetic variances. The estimated additive genetic variance in extra-pair siring probability was larger, although the 95% credible interval still converged towards zero. Siring probability also showed inbreeding depression and increased with male age, while the numbers of available broods and offspring per brood did not. 5. Our results indicate that the probability that a male will sire an EPO in an available brood is the primary source of genetic variation in male EPRS, implying that the evolution of female extra-pair reproduction could be facilitated by genetic covariance with this subcomponent of EPRS., Usage notesPhenotypic data: number of available broodsThis file contains the phenotypic data for the univariate quantitative genetic analyses of the number of available broods (Nbroods).Nbrood.dryad.txtPhenotypic data: Psire and number of available offspringPhenotypic data for the univariate quantitative genetic analyses of the probability that an offspring within an available brood (or litter) will be sired as an EPO by a focal male (Psire) and the number of available offspring.Psire.dryad.txtPedigree for Psire, Nbroods, and number of offspringThis file contains the non-zero elements of the inverted A (relationship) matrix data for the animal model analyses of Psire, Nbroods, and number of offspring.pedigree1_dryad.txtPedigree for analysis of Pat.successThis file contains the non-zero elements of the inverted A (relationship) matrix data for the animal model analysis of Pat.success.pedigree2_dryad.txtPhenotypic data: Ppat.successThis file contains the phenotypic data for the univariate quantitative genetic analyses of the probability that an offspring within an available brood (or litter) will be sired as an additional EPO by a focal male given that he sired one EPO in that brood (Ppat.success).Ppat.dryad.txt### 摘要 1. 配对外繁殖成功率（Extra-pair reproductive success, EPRS）是社会单配制体系中雄性适合度的核心组成部分；若配对后代（extra-pair offspring, EPO）可从其成功的配对父本处继承高EPRS值，则该性状可能对雌性的配对外繁殖产生选择压力。然而，EPRS本身是一个复合性状，可完全分解为多个变异子组分，每个子组分还可进一步划分为遗传方差与环境方差。但目前野生种群中尚未开展此类分解研究，这阻碍了进化推断的推进。 2. 本研究首先证明，EPRS可分解为三个生活史子组分的乘积：目标雄性可用于产生配对后代的繁殖窝数、该雄性在可利用繁殖窝中产下配对后代的概率，以及可利用繁殖窝中的后代数量。该EPRS分解方式便于从野外数据中进行参数估计，因为所有子组分均可通过父权鉴定数据量化，无需直接统计配对外交配事件。此外，本分解框架还揭示，可利用繁殖窝数量（进而涉及种群结构与种群动态）可能对雄性EPRS及适合度的变异产生显著贡献。 3. 随后，本研究利用野生歌带鹀（Melospiza melodia）长达20年的完整遗传父权鉴定数据与谱系数据，对EPRS三个子组分的方差进行拆分，并以此估算各子组分的加性遗传方差与遗传力，同时控制雄性近交系数、年龄与社会地位的效应。 4. EPRS的三个子组分均表现出一定程度的雄性内重复性，这反映了永久性环境效应与遗传效应的共同作用。可利用繁殖窝数与每窝后代数的加性遗传方差较低。尽管95%可信区间仍趋近于0，但配对外受精概率的估算加性遗传方差相对更高。此外，受精概率存在近交衰退现象，且随雄性年龄增长而升高，而可利用繁殖窝数与每窝后代数则无此特征。 5. 本研究结果表明，雄性在可利用繁殖窝中产下配对后代的概率是雄性EPRS遗传变异的主要来源，这意味着雌性配对外繁殖的演化可通过与EPRS该子组分的遗传协变得到促进。 ### 使用说明 #### 表型数据：可利用繁殖窝数 本文件包含针对可利用繁殖窝数（Nbroods）的单变量数量遗传分析所需的表型数据，文件名为：Nbrood.dryad.txt。 #### 表型数据：Psire与可利用后代数 本文件包含两项单变量数量遗传分析所需的表型数据：一是目标雄性在可利用繁殖窝（或产仔窝）中产下配对后代的概率（Psire），二是可利用繁殖窝中的后代数量，文件名为：Psire.dryad.txt。 #### Psire、Nbroods与后代数的谱系数据 本文件包含针对Psire、可利用繁殖窝数及后代数进行动物模型分析所需的逆A（亲缘关系）矩阵的非零元素数据，文件名为：pedigree1_dryad.txt。 #### Pat.success分析用谱系数据 本文件包含针对Pat.success进行动物模型分析所需的逆A（亲缘关系）矩阵的非零元素数据，文件名为：pedigree2_dryad.txt。 #### 表型数据：Ppat.success 本文件包含针对Ppat.success的单变量数量遗传分析所需的表型数据。Ppat.success指：若目标雄性已在某繁殖窝中产下一枚配对后代，则其在该窝中再次产下配对后代的概率，文件名为：Ppat.dryad.txt。