Maternal or early life effects may prepare offspring for similar social conditions to those experienced by their mothers. For males, the ability to achieve mating and fertilization success is a key social challenge. Competitive conditions may therefore favour increased body size or ejaculate production in male offspring. We tested this experimentally by comparing reproductive traits of adult male bank voles (Myodes glareolus), whose mothers had experienced contrasting encounter regimes with female conspecifics while breeding. We found that daily sperm production rates and epididymis mass were significantly higher when dams had experienced more frequent encounters with female conspecifics. This response to maternal and early life experience was specific to sperm production and storage, with no evidence for effects on male body mass or the size of testes and accessory reproductive glands. Our findings reveal a potentially adaptive effect of maternal and early life experience on the development of sperm production, which is worthy of wider investigation.

母亲或早期生活的影响可能会让后代为与母亲经历的类似的社会条件做好准备。对于雄性来说，成功交配和受精的能力是一项关键的社会挑战。因此，竞争条件可能有利于雄性后代体型的增大或射精量的增加。我们通过比较成年雄性田鼠（ Myodes glareolus ）的生殖特征进行了实验测试，这些田鼠的母亲在繁殖过程中经历了与雌性同种截然不同的遭遇方式。我们发现，当母鼠更频繁地接触雌性同种动物时，每日精子生成率和附睾质量显着更高。这种对母亲和早期生活经历的反应特定于精子的产生和储存，没有证据表明对男性体重或睾丸和辅助生殖腺的大小有影响。我们的研究结果揭示了母亲和早期生活经历对精子产生发展的潜在适应性影响，这值得更广泛的研究。