Supplementary Figure S1 and Table S1 from Social status and ejaculate composition in the house mouse

Sperm competition theory predicts that males should tailor ejaculates according to their social status. Here, we test this in a model vertebrate, the house mouse (<i>Mus musculus domesticus</i>), combining experimental data with a quantitative proteomics analysis of seminal fluid composition. Our analyses reveal that both sperm production and the composition of proteins found in seminal vesicle secretions differ according to social status. Dominant males invested more in ejaculate production overall. Their epididymides contained more sperm than those of subordinate or control males, despite similar testes size between the groups. Dominant males also had larger seminal vesicle glands than subordinate or control males, despite similar body size. However, the seminal vesicle secretions of subordinate males had a significantly higher protein concentration than those of dominant males. Moreover, detailed proteomic analysis revealed subtle but consistent differences in the composition of secreted seminal vesicle proteins according to social status, involving multiple proteins of potential functional significance in sperm competition. These findings have significant implications for understanding the dynamics and outcome of sperm competition, and highlight the importance of social status as a factor influencing both sperm and seminal fluid investment strategies.This article is part of the theme issue ‘Fifty years of sperm competition’.

精子竞争（sperm competition）理论预测，雄性可根据自身社会地位调整射精策略。本研究以模式脊椎动物家鼠（*Mus musculus domesticus*）为实验对象，结合实验数据与精浆成分的定量蛋白质组学（quantitative proteomics）分析，对该理论开展验证。分析结果显示，精子生成量与精囊腺分泌蛋白的组成均会随社会地位的不同而发生显著差异。总体而言，优势雄性在射精相关产出上的投入更高：尽管各组小鼠的睾丸尺寸无显著差异，但优势雄性附睾内的精子数量多于从属地位雄性与对照组雄性；尽管各组小鼠的体型大小无显著差异，但优势雄性的精囊腺体积也大于从属地位雄性与对照组雄性。然而，从属地位雄性的精囊腺分泌液蛋白浓度显著高于优势雄性。此外，精细化的蛋白质组学分析还发现，精囊腺分泌蛋白的组成会随社会地位呈现细微但稳定的差异，涉及多种在精子竞争中具备潜在功能重要性的蛋白质。本研究结果对于理解精子竞争的动态过程与结局具有重要意义，并凸显了社会地位作为影响精子与精浆投入策略的关键因素的重要性。本文隶属于“精子竞争五十年”专题议题。