School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
Anim Reprod Sci. 2012 Apr;131(3-4):109-22. doi: 10.1016/j.anireprosci.2012.02.007. Epub 2012 Feb 22.
Sexual dimorphisms (SDs) have evolved in mammals to assure greater reproductive success for individuals, usually males. Secondary sexual characteristics (SSC) developed to further this objective, tending to be more pronounced in species which are polygynous, diurnal and open-habitat dwellers. Sexual selection has underpinned many of these changes, which are not necessarily advantageous for individual survival. Domestication has affected certain characteristics, more in terms of their quantitative rather than qualitative expression. However, restrictions imposed by domestication can also affect behaviors such as isolation and post-natal bonding while artificial selection can, by focusing on certain traits, cause unforeseen effects in genetically linked traits, which, when sex-specific or sex-linked, can be reflected in SD. On a global scale, environmental changes can have important phylogenetic implications for species which rely upon environmental cues for activities as migration, hibernation and breeding, especially when SD occurs in response to such cues. Understanding the evolutionary rationale behind the development of SDs, as well as the dynamics which occur at the interface between natural and artificial selection, allows positive insights into areas as diverse as wildlife preservation and livestock management. For both, greatest "success" should be achieved when artificial selection occurs in harmony with natural selection within a supportive environment. Thus the aim of this review is to discuss current knowledge relating to the evolution, benefits and costs of mammalian sexual dimorphisms and, where possible, draw conclusions that might be beneficial for the husbandry and propagation of mammals today.
哺乳动物中存在性二态性（SD），以确保个体（通常是雄性）有更高的繁殖成功率。第二性征（SSC）的发展是为了进一步实现这一目标，在那些多配偶制、昼行性和开阔栖息地居住的物种中，这些特征往往更为明显。性选择是这些变化的基础，这些变化并不一定对个体的生存有利。驯化影响了某些特征，更多的是在其数量而不是质量表达方面。然而，驯化所施加的限制也会影响隔离和产后结合等行为，而人工选择可以通过关注某些特征，导致与遗传相关的特征出现意想不到的影响，这些特征在特定性别或性连锁时，可以反映在性二态性中。在全球范围内，环境变化对依赖环境线索进行活动的物种（如迁徙、冬眠和繁殖）具有重要的系统发育意义，特别是当 SD 是对这些线索的反应时。了解 SD 发展背后的进化原理，以及自然选择和人工选择之间界面上发生的动态，可以为野生动物保护和家畜管理等领域提供积极的见解。对于这两个领域，当人工选择与自然选择在支持性环境中和谐共存时，应该取得最大的“成功”。因此，本综述的目的是讨论与哺乳动物性二态性的进化、益处和成本相关的现有知识，并在可能的情况下得出对当今哺乳动物饲养和繁殖有益的结论。
