Andrological Records of Swiss Male Mice

Male sexual behavior has traditionally been viewed as genetically determined and highly stereotyped, leading to the assumption that ejaculatory phenotypes are stable traits, potentially serving as genetically inherited endophenotypes. However, how consistent, i.e., how they diverge after being challenged by intrinsic and/or extrinsic factors among the population, remains insufficiently studied. Evidence suggests that behavioral manifestations are highly variable, transient, and adaptable over time. Moreover, interactions between behavioral and cognitive traits could influence the stability of endophenotypes. Here, we assessed the anxiety index (AI) in a naturally anxious mouse strain, the adult Swiss males, using a single session in the elevated plus maze before and after seven copulatory encounters. Males were phenotyped as fast, average, slow, or sluggish ejaculators based on mean ejaculation latency (EL) and categorized as high, middle, low, or non-ejaculators based on accumulated ejaculation number (EN). We also measured morphometric and andrological characteristics. To evaluate the consistency of these ejaculatory endophenotypes, we performed hierarchical clustering and principal component analysis using AI as an external factor or covariate.