Higher social status is expected to result in fitness benefits as it secures access to potential mates. In promiscuous species, male reproductive success is also determined by an individual’s ability to compete for fertilization after mating by producing high-quality ejaculates. However, the complex relationship between a male’s investment in social status and ejaculates remains unclear. Here, we examine how male social status influences ejaculate quality under a range of social contexts in the pygmy halfbeak Dermogenys collettei, a small, group-living, internally fertilizing freshwater fish. We show that male social status influences ejaculate traits, both in the presence and absence of females. Dominant males produced faster swimming and more viable sperm, two key determinants of ejaculate quality, but only under conditions with frequent male–male behavioral interactions. When male–male interactions were experimentally reduced through the addition of a refuge, differences in ejaculate traits of dominant and subordinate males disappeared. Furthermore, dominant males were in a better condition, growing faster, and possessing larger livers, highlighting a possible condition dependence of competitive traits. Contrary to expectations, female presence or absence did not affect sperm swimming speed or testes mass. Together, these results suggest a positive relationship between social status and ejaculate quality in halfbeaks and highlight that the strength of behavioral interactions between males is a key driver of social-status-dependent differences in ejaculate traits.

中文翻译：

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男性与男性之间的行为互动推动射精特质的社会主导性差异

较高的社会地位有望带来健身益处，因为它可以确保与潜在配偶的接触。在杂种中，雄性繁殖的成功还取决于个体交配后通过生产优质射精而竞争受精的能力。但是，男性对社会地位的投入与射精之间的复杂关系仍然不清楚。在这里，我们研究了侏儒半喙Dermogenys collettei在一系列社会背景下男性的社会地位如何影响射精质量，是一种小型的，有群体生活的内部施肥的淡水鱼。我们表明，无论有无女性，男性的社会地位都会影响射精特征。雄性雄性产生更快的游泳速度和更强的精子活力，这是决定射精质量的两个关键因素，但仅在频繁发生雄性-雄性行为相互作用的条件下。当通过增加庇护所实验性地减少了男性与男性的互动时，优势男性和从属男性的射精特征的差异就消失了。此外，优势男性的状况更好，生长更快，肝脏更大，这突出说明了竞争特征可能与条件有关。与预期相反，女性的有无并不影响精子的游泳速度或睾丸质量。一起，