Data from: Effects of ovarian fluid on sperm traits and its implications for cryptic female choice in zebrafish

In polyandrous mating systems, females maintain the opportunity to bias male fertilization success after mating in a process known as cryptic female choice. Mechanisms of cryptic female choice have been described both in internal and external fertilizers, and may affect fertilization processes at different stages before, during and after fertilization. While in internal fertilizers, females have substantial control over sperm storage and fertilization, in external fertilizers, female control is limited. A key factor proposed to mediate cryptic female choice is the fluid surrounding the eggs, the ovarian fluid, as it may directly affect sperm performance. Here, we studied the role of ovarian fluid in post-mating sexual selection using the zebrafish, Danio rerio. Firstly, we assessed how ovarian fluid affects sperm swimming performance compared to freshwater. We focussed on sperm motility, velocity, swimming trajectory and longevity, all traits associated with competitive fertilization success in externally fertilizing fish. In a second step, we used a North Carolina II design to explore female, male, and female x male effects by testing sperm motility of two males in the ovarian fluid of two females in a total of eleven blocks. Our results suggest that the ovarian fluid affects sperm performance differently from freshwater. Specifically, sperm velocity, motility and longevity were higher in the ovarian fluid than in freshwater, whereas sperm linearity and beat cross frequency showed the opposite pattern. Moreover, these effects varied according to male and female identities, supporting the potential for cryptic female choice mediated by ovarian fluid in this species.,Freshwater vs Ovarian fluid effect on sperm traitsEffect of ovarian fluid compared to freshwater on different sperm traits measured every ten seconds for the first minute after sperm activation (sperm curvilinear velocity VCL, sperm linearity LIN, sperm beat-cross frequency BFC, sperm motility, proportion of motile sperm)FRF dataset.csvRepeatability measurements of sperm motility traits in freshwater and ovarian fluidRepeatability measurements of sperm traits (sperm curvilinear velocity VCL, sperm linearity LIN, sperm beat-cross frequency BFC, sperm motility, proportion of motile sperm) in freshwater and ovarian fluid measured every ten seconds for the first minute after sperm activation.REPEATABILITY.csv,在一妻多夫制交配体系中，雌性具备在交配后偏倚雄性受精成功率的机会，该过程被称为隐蔽雌性选择（cryptic female choice）。隐蔽雌性选择的机制已在体内受精与体外受精类群中被报道，可在受精前、受精时及受精后的不同阶段对受精过程产生影响。对于体内受精物种，雌性对精子储存与受精过程拥有较强的调控能力；而在体外受精物种中，雌性的调控能力则相对有限。目前被提出用于介导隐蔽雌性选择的关键因素是卵细胞周围的液体——卵巢液（ovarian fluid），因其可直接影响精子的运动表现。本研究以斑马鱼（Danio rerio）为实验对象，探讨了卵巢液在交配后性选择中的作用。 首先，我们以淡水环境为对照，评估了卵巢液对精子运动性能的影响。本研究重点关注与体外受精鱼类竞争性受精成功率相关的精子运动性、运动速度、游泳轨迹及寿命等性状。其次，我们采用北卡罗来纳II型设计（North Carolina II design），通过将2尾雄性的精子分别置于2尾雌性的卵巢液中进行检测，共设置11个重复组，以此探究雌性、雄性以及雌性×雄性的交互效应。 研究结果表明，卵巢液对精子运动性能的影响与淡水环境存在显著差异。具体而言，卵巢液环境中的精子运动速度、运动性及寿命均高于淡水环境，而精子线性度与跨频搏动频率则呈现相反的变化趋势。此外，这些效应因雄性与雌性的个体身份而异，这支持了本物种中卵巢液介导的隐蔽雌性选择的潜在可能性。 淡水与卵巢液对精子性状的影响 本数据集包含精子激活后首分钟内每10秒测定的各类精子性状数据，涵盖精子曲线速度（sperm curvilinear velocity, VCL）、精子线性度（sperm linearity, LIN）、精子跨频搏动频率（sperm beat-cross frequency, BFC）、精子运动性（活动精子占比）。对应数据文件为FRF dataset.csv。 淡水与卵巢液环境下精子运动性状的重复性测定 本数据集包含精子激活后首分钟内每10秒测定的淡水与卵巢液环境下的各类精子性状重复性测量数据，涵盖精子曲线速度（sperm curvilinear velocity, VCL）、精子线性度（sperm linearity, LIN）、精子跨频搏动频率（sperm beat-cross frequency, BFC）、精子运动性（活动精子占比）。对应数据文件为REPEATABILITY.csv。