A competitive environment influences sperm production, but not testes tissue composition, in house mice

Due to the physiological cost of sperm production, males are expected to be prudent in their expenditure and adjust their investment according to current social conditions. Strategic adjustments in sperm expenditure during development can be made via changes in testes size, sperm production rates, or testes tissue composition. Here, using house mice, we test the hypothesis that elevated sperm production is driven by a plastic response in the spatial organisation of the testes. We reared males under different social conditions (competitive vs. non-competitive) and quantified sperm number and the proportion of sperm‐producing tissue within the testes. Further, because sperm quality is a critical determinant of competitive fertilization success, we used computer-assisted sperm analysis to quantify six sperm motility traits. Our investigation revealed that males reared in an environment with a perceived risk of reproductive competition produced more sperm in the absence of changes in testes...

鉴于精子生成存在生理成本，雄性个体理应审慎分配资源投入，并依据当前社会情境调整繁殖投资策略。发育过程中，精子投入的策略性调整可通过改变睾丸尺寸、精子生成速率或睾丸组织组成来实现。本研究以小家鼠为实验对象，验证了“精子生成量提升是由睾丸空间结构的可塑性响应所驱动”这一假说。我们将雄性小家鼠饲养于两种不同社会情境下（存在繁殖竞争vs.无繁殖竞争），并对其精子数量以及睾丸内产精子组织的占比进行了定量检测。此外，由于精子质量是决定竞争受精成功率的关键因素，我们采用计算机辅助精子分析（computer-assisted sperm analysis, CASA）技术，定量检测了六项精子运动参数。本研究结果显示，处于感知存在繁殖竞争风险环境中的雄性个体，在睾丸尺寸未发生改变的情况下，精子生成量更高……