Baculum shape and paternity success in house mice: evidence for genital coevolution

Sexual selection is believed to be responsible for the rapid divergence of male genitalia, which is a widely observed phenomenon across different taxa. Among mammals, the stimulatory role of male genitalia and female ‘sensory perception’ has been suggested to explain these evolutionary patterns. Recent research on house mice has shown that baculum (penis bone) shape can respond to experimentally imposed sexual selection. Here, we explore the adaptive value of baculum shape by performing two experiments that examine the effects of male and female genitalia on male reproductive success. Thus, we selected house mice (Mus musculus domesticus) from families characterised by extremes in baculum shape (relative width) and examined paternity success in both non-competitive (monogamous) and competitive (polyandrous) contexts. Our analyses revealed that the relative baculum shape of competing males influenced competitive paternity success, but that this effect was dependent on the breeding value for baculum shape of the family from which females were derived. Our data provide novel insight into the potential role of sexual selected on the coevolution of the house mouse baculum and lend support to the stimulatory hypothesis for mammalian genital evolution.,Dataset 1-6: Landmarks were placed around the periphery of the baculum (36 sliding, 4 fixed) and relative warps (RWs) and centroid size were extracted. Landmark placement conducted using tpsDig 232 developed by Rohlf. Dataset 7-8: Methodology explained in detail in the paper.,Dataset 1: Landmark data from second-generation laboratory-reared house mice. Dataset 2: Landmark data from second-generation laboratory-reared house mice used for the monoandrous mating experiment. Specimen number (ID) can be matched with ID at the excel spreadsheet from Dataset 7. Dataset 3: Landmark data from second-generation laboratory-reared house mice used to conduct a repeatability analysis. For the same individual, we have two sets of landmarks. Used to assess the repeatability of landmark placement. Specimen numbers/ID can be matched with ID at the Dataset 7 Dataset 4: Landmark data from third-generation laboratory-reared house mice. Dataset 5: Landmark data from third-generation laboratory-reared house mice used for the polyandrous mating experiment. Specimen number (ID) can be matched with ID at the excel spreadsheet from Dataset 8. Dataset 6: Landmark data from third-generation laboratory-reared house mice used to conduct a repeatability analysis. For the same individual, we have two sets of landmarks. Used to assess the repeatability of landmark placement. Specimen numbers/ID can be matched with ID at the Dataset 8. Dataset 7: Excel spreadsheet containing morphological data and identifiers of each individual for the second-generation laboratory reared house mice and monoandrous mating experiment. Dataset contains three different sheets representing data used for three different analysis. Second-generation sheet: data used to check if 2nd generation house mice aligned with the expected baculum shape extremes; Monoandrous experiment data: data used to conduct the statistical analysis on the monoandrous mating experiments; Second-generation Repeatibility: data used for the analysis of reliability of landmark placement and repeatability of our measurements. Dataset 8: Excel spreadsheet containing morphological data and identifiers of each individual for the second-generation laboratory reared house mice and polyandrous mating experiment. Third-generation sheet: data used to check if 3rd generation house mice aligned with the expected baculum shape extremes; Polyandrous experiment data: data used to conduct the statistical analysis on the monoandrous mating experiments; Third-generation Repeatibility: data used for the analysis of reliability of landmark placement and repeatability of our measurements.,

普遍认为，性选择是导致雄性生殖器快速分化的核心诱因，该现象在各类分类群中均有广泛观测记录。在哺乳动物类群中，已有假说提出雄性生殖器的刺激作用与雌性的「感官感知」可解释这类演化模式。近期针对小家鼠（Mus musculus domesticus）的研究表明，阴茎骨（baculum）的形态可对实验施加的性选择产生响应。本研究通过两项实验探究雄性与雌性生殖器对雄性繁殖成功率的影响，以此解析阴茎骨形态的适应性价值。我们从阴茎骨形态（相对宽度）处于极端值的家系中选育小家鼠，随后在非竞争（单配偶制）与竞争（多配偶制）两种情境下检测其父权成功率。分析结果显示，竞争雄性的阴茎骨相对形态会影响竞争性父权成功率，但该效应依赖于雌性来源家系的阴茎骨形态育种值。本研究数据为性选择在小家鼠阴茎骨协同演化中的潜在作用提供了全新见解，并为哺乳动物生殖器演化的刺激假说提供了实证支撑。
数据集1-6：在阴茎骨（baculum）的外周轮廓放置地标（36个滑动地标、4个固定地标），并提取相对扭曲（relative warps，RWs）与形心大小（centroid size）。地标放置操作由Rohlf开发的tpsDig232软件完成。
数据集7-8：详细实验方法见论文正文。
数据集1：来自第二代实验室饲养小家鼠的地标数据。
数据集2：用于单配偶制交配实验的第二代实验室饲养小家鼠的地标数据。样本编号（ID）可与数据集7的Excel表格中的ID进行匹配。
数据集3：用于重复性分析的第二代实验室饲养小家鼠的地标数据。针对同一个体，我们拥有两组地标数据，用于评估地标放置操作的可重复性。样本编号/ID可与数据集7中的ID进行匹配。
数据集4：来自第三代实验室饲养小家鼠的地标数据。
数据集5：用于多配偶制交配实验的第三代实验室饲养小家鼠的地标数据。样本编号（ID）可与数据集8的Excel表格中的ID进行匹配。
数据集6：用于重复性分析的第三代实验室饲养小家鼠的地标数据。针对同一个体，我们拥有两组地标数据，用于评估地标放置操作的可重复性。样本编号/ID可与数据集8中的ID进行匹配。
数据集7：包含第二代实验室饲养小家鼠的形态学数据与个体标识符的Excel表格，同时涵盖单配偶制交配实验相关数据。该表格包含三个不同工作表，分别对应三种不同分析所用的数据：第二代工作表：用于验证第二代小家鼠的阴茎骨形态是否符合预期的极端值；单配偶制实验数据表：用于对单配偶制交配实验开展统计分析；第二代重复性分析工作表：用于评估地标放置可靠性与测量重复性的分析数据。
数据集8：包含第三代实验室饲养小家鼠的形态学数据与个体标识符的Excel表格，同时涵盖多配偶制交配实验相关数据。该表格包含三个不同工作表，分别对应三种不同分析所用的数据：第三代工作表：用于验证第三代小家鼠的阴茎骨形态是否符合预期的极端值；多配偶制实验数据表：用于对单配偶制交配实验开展统计分析；第三代重复性分析工作表：用于评估地标放置可靠性与测量重复性的分析数据。