Social status and ejaculate investment in the house mouse c4pr_liv

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 (Mus musculus domesticus), combining experimental data with a quantitative proteomics analysis of seminal fluid composition. Our analyses reveal that both sperm production and the relative production of proteins found in seminal fluid differ according to social dominance. Notably, whereas dominant males produce and ejaculate more sperm, subordinate males produce greater relative amounts of key proteins used in the formation of copulatory plugs. These findings have important implications for understanding the dynamics and outcome of sperm competition.