背景:在一夫多妻制物种中,第二性征的发展通常是男性生殖成功的决定性因素。然而,我们对这些性状的生长与生殖效率之间的联系的理解仍然难以捉摸。该主题的大多数研究工作也集中在成年男性身上,虽然一些第二性征的发展,像牛角一样,通常在出生后开始,在青春期和某些物种中继续,比如普通的土地,在成年期减慢甚至停止。在这项研究中,我们采用综合考虑生精参数和精子参数的综合方法,研究了普通地区性发育过程中角大小与睾丸功能之间的关系。方法:本研究使用22种非性成熟的普通eland。喇叭大小,体重,睾丸质量,和性腺指数进行评估。通过细胞学和组织学分析确定生精活性。精子浓度,形态学,形态计量学,在附睾精子样本上评估精子大小的膜内变化。进行聚类分析以探讨年龄对角大小与生殖功能之间关系的影响。结果:我们发现较大的角与睾丸支持细胞效率增加和精子大小内变异减少有关。这两个参数彼此无关,但已显示它们与有蹄类动物的精子质量增强有关。此外,角的大小与睾丸质量呈正相关,精子浓度,和睾丸对生精上皮的投资。螺旋长度和基围是与生精和精子参数以及与该物种性二态性有关的角特征。聚类分析分为两组:第一组包括≤30个月的男性,而第二个是>30个月大。角发育和生殖功能在年龄组内仍然相关,在>30个月的男性中,角大小与精子大小同质性之间的关系最强。结论:综合来看,我们的结果表明,角大小可以被认为是性发育过程中男性生殖潜力的良好指标,并提供了对第二性征在性选择动态中的作用的见解。
Background: In polygynous species, the development of secondary sexual characters is usually decisive for male reproductive success. However, our understanding about the links between the growth of these traits and reproductive efficiency is still elusive. Most research efforts in this topic have been also focused on adult males, although the development of some secondary sexual characters, like bovid horns, typically starts after birth, continues during the puberty and in some species, such as the common eland, slows or even stops during adulthood. In this study, we investigated the relationships between horn size and testicular function during sexual development in common elands using a comprehensive approach that considers both spermatogenic and sperm parameters. Methods: Twenty-two non-sexually mature common elands were used for the present study. Horn size, body mass, testes mass, and gonadosomatic index were assessed. Spermatogenic activity was determined by cytological and histological analyses. Sperm concentration, morphology, morphometry, and intramale variation in sperm size were evaluated on epididymal sperm samples. Cluster analysis was performed to explore the influence of age on relationships between horn size and reproductive function. Results: We found that bigger horns are associated with increased Sertoli cell efficiency and reduced intramale variation in sperm size. Both parameters were not related to one another while they have shown to be associated with enhanced sperm quality in ungulates. Moreover, horn size was positively linked to the testis mass, sperm concentration, and testicular investment in the seminiferous epithelium. Spiral length and basal circumference were the horn traits most strongly correlated with spermatogenic and sperm parameters as well as those responsible for the sexual dimorphism in this species. Cluster analysis rendered two groups: the first one including males ≤30 months old, while the second one those >30 months old. Horn development and reproductive function were still correlated within age groups, with the strongest relationship found between horn size and sperm size homogeneity in males >30 months old. Conclusion: Taken together, our results indicate that horn size can be regarded as a good index of male reproductive potential during sexual development and provide insights into the role of secondary sexual characters in sexual selection dynamics.