Ambaryan A B, Maltzev A N, Kotenkova E V
Zh Obshch Biol. 2015 May-Jun;76(3):212-24.
Some physiological parameters that determine quality of male sperm (its concentration, spermatozoa morphology) and testicle size vary in integrity, i.e. the bigger are testicles the higher is sperm quality. Therefore, the estimate of testicles relative mass is often used as a characteristic of sperm competitive ability when comparing phylogenetically close mammal species. In house mice belonging to the superspecies complex Mus musculus s.l., testicles relative mass is greater in exoanthropic species than in synanthropic ones. It is shown in our study that this pattern is apparent also at the intraspecies level since testicles mass index, sperm concentration, and percentage of morphologically normal spermatozoa in subspecies Mus musculus wagneri, which is facultatively synanthropic, are higher compared with synanthropic subspecies M m. musculus. An analysis of sexual behavior of the three forms (namely, exoanthropic species M. spicilegus and two subspecies mentioned above) indicates that in M. spicilegus both sexual behavior efficiency and ejaculation rate during coupling were higher as compared with other two subspecies. Based on the analysis of life pattern, reproduction systems, and group spatial-ethological structure, the hypotheses are formulated that explain the maintenance of selection directed to increase of sperm competitive ability in exoanthropic house mice species.
一些决定雄性精子质量（精子浓度、精子形态）和睾丸大小的生理参数在完整性方面存在差异，即睾丸越大，精子质量越高。因此，在比较系统发育关系相近的哺乳动物物种时，睾丸相对质量的估计常被用作精子竞争能力的一个特征。在属于小家鼠复合种（Mus musculus s.l.）的家鼠中，外栖物种的睾丸相对质量大于共栖物种。我们的研究表明，这种模式在种内水平上也很明显，因为兼性共栖的亚种瓦格纳小家鼠（Mus musculus wagneri）的睾丸质量指数、精子浓度和形态正常精子的百分比高于共栖亚种小家鼠（M. m. musculus）。对三种类型（即外栖物种尖齿鼠（M. spicilegus）和上述两个亚种）性行为的分析表明，与其他两个亚种相比，尖齿鼠在交配期间的性行为效率和射精率都更高。基于对生活模式、繁殖系统和群体空间行为结构的分析，提出了一些假设，用以解释在外栖家鼠物种中维持旨在提高精子竞争能力的选择的原因。
