Ball Gregory F, Ketterson Ellen D
Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
Philos Trans R Soc Lond B Biol Sci. 2008 Jan 27;363(1490):231-46. doi: 10.1098/rstb.2007.2137.
Although it is axiomatic that males and females differ in relation to many aspects of reproduction related to physiology, morphology and behaviour, relatively little is known about possible sex differences in the response to cues from the environment that control the timing of seasonal breeding. This review concerns the environmental regulation of seasonal reproduction in birds and how this process might differ between males and females. From an evolutionary perspective, the sexes can be expected to differ in the cues they use to time reproduction. Female reproductive fitness typically varies more as a function of fecundity selection, while male reproductive fitness varies more as a function sexual selection. Consequently, variation in the precision of the timing of egg laying is likely to have more serious fitness consequences for females than for males, while variation in the timing of recrudescence of the male testes and accompanying territory establishment and courtship are likely to have more serious fitness consequences for males. From the proximate perspective, sex differences in the control of reproduction could be regulated via the response to photoperiod or in the relative importance and action of supplementary factors (such as temperature, food supply, nesting sites and behavioural interactions) that adjust the timing of reproduction so that it is in step with local conditions. For example, there is clear evidence in several temperate zone avian species that females require both supplementary factors and long photoperiods in order for follicles to develop, while males can attain full gonadal size based on photoperiodic stimulation alone. The neuroendocrine basis of these sex differences is not well understood, though there are many candidate mechanisms in the brain as well as throughout the entire hypothalamo-pituitary-gonadal axis that might be important.
虽然雄性和雌性在与生殖相关的生理、形态和行为等许多方面存在差异是不言而喻的，但对于控制季节性繁殖时间的环境线索的反应中可能存在的性别差异，我们所知甚少。这篇综述关注鸟类季节性繁殖的环境调节以及这个过程在雄性和雌性之间可能存在的差异。从进化的角度来看，可以预期两性在用于确定繁殖时间的线索上存在差异。雌性的生殖适应性通常更多地随繁殖力选择而变化，而雄性的生殖适应性更多地随性选择而变化。因此，产卵时间的精确性变化对雌性的适应性影响可能比对雄性更严重，而雄性睾丸再发育的时间以及随之而来的领地建立和求偶行为的时间变化对雄性的适应性影响可能更严重。从近因角度来看，生殖控制中的性别差异可能通过对光周期的反应或在调节繁殖时间以使其与当地条件同步的补充因素（如温度、食物供应、筑巢地点和行为相互作用）的相对重要性和作用方面进行调节。例如，在几种温带鸟类物种中有明确证据表明，雌性需要补充因素和长光周期才能使卵泡发育，而雄性仅基于光周期刺激就能达到性腺的完全大小。尽管大脑以及整个下丘脑 - 垂体 - 性腺轴中有许多可能重要的候选机制，但这些性别差异的神经内分泌基础尚未得到很好的理解。
