Krackow S
Biol Rev Camb Philos Soc. 1995 May;70(2):225-41. doi: 10.1111/j.1469-185x.1995.tb01066.x.
Sex ratio skews in relation to a variety of environmental or parental conditions have frequently been reported among mammals and, though less commonly, among birds. However, the adaptive significance of such sex ratio variation remains unclear. This has, in part, been attributed to the absence of a low-cost physiological mechanism for sex ratio manipulation by the parent. It is shown here that several recent findings in reproductive biology are suggestive of many potential pathways by which gonadotropins and steroid hormones could interfere with the sex ratio at birth. And these hormone levels are well-known to be influenced by many parameters which have been invoked in correlating with offspring sex ratios. Hence, it is argued that the significant, but inconsistent sex ratio biases reported in mammalian and avian populations are coherent with current knowledge on reproductive physiology in those species. However, whether such variations can be viewed at as a consequence of physiological constraint or as adaptive sex ratio adjustment, has still to be determined.
在哺乳动物中，经常有报道称性别比例会因各种环境或亲代条件而出现偏差，鸟类中也有此类情况，不过相对较少。然而，这种性别比例变化的适应性意义仍不明确。部分原因在于缺乏一种亲代操纵性别比例的低成本生理机制。本文表明，生殖生物学领域最近的一些发现提示了促性腺激素和类固醇激素可能干扰出生时性别比例的多种潜在途径。而且众所周知，这些激素水平会受到许多与后代性别比例相关的参数影响。因此，有人认为在哺乳动物和鸟类种群中报道的显著但不一致的性别比例偏差与这些物种当前的生殖生理学知识是相符的。然而，这种变化究竟是生理限制的结果还是适应性性别比例调整，仍有待确定。
