Adkins-Regan Elizabeth
Department of Psychology, Uris Hall, Cornell University, Ithaca, NY 14853-7601, USA.
Philos Trans R Soc Lond B Biol Sci. 2008 May 12;363(1497):1599-609. doi: 10.1098/rstb.2007.0005.
Hormonal control systems are complex in design and well integrated. Concern has been raised that these systems might act as evolutionary constraints when animals are subject to anthropogenic environmental change. Three systems are examined in vertebrates, especially birds, that are important for assessing this possibility: (i) the hypothalamic-pituitary-gonadal (HPG) axis, (ii) the activational effects of sex steroids on mating effort behaviour, and (iii) sexual differentiation. Consideration of how these systems actually work that takes adequate account of the brain's role and mechanisms suggests that the first two are unlikely to be impediments to evolution. The neural and molecular networks that regulate the HPG provide both phenotypic and evolutionary flexibility, and rapid evolutionary responses to selection have been documented in several species. The neuroendocrine and molecular cascades for behaviour provide many avenues for evolutionary change without requiring a change in peripheral hormone levels. Sexual differentiation has some potential to be a source of evolutionary inertia in birds and could contribute to the lack of diversity in certain reproductive (including life history) traits. It is unclear, however, whether that lack of diversity would impede adaptation to rapid environmental change given the role of behavioural flexibility in avian reproduction.
激素控制系统设计复杂且整合良好。有人担心，当动物面临人为环境变化时，这些系统可能会成为进化限制因素。本文研究了脊椎动物，尤其是鸟类中对评估这种可能性很重要的三个系统：（i）下丘脑 - 垂体 - 性腺（HPG）轴，（ii）性类固醇对交配行为的激活作用，以及（iii）性别分化。充分考虑大脑作用和机制来思考这些系统实际如何运作表明，前两个系统不太可能成为进化的障碍。调节HPG的神经和分子网络提供了表型和进化的灵活性，并且在几个物种中都记录了对选择的快速进化反应。行为的神经内分泌和分子级联反应为进化变化提供了许多途径，而无需外周激素水平的改变。性别分化在鸟类中有可能成为进化惯性的一个来源，并且可能导致某些生殖（包括生活史）性状缺乏多样性。然而，鉴于行为灵活性在鸟类繁殖中的作用，尚不清楚这种多样性的缺乏是否会阻碍对快速环境变化的适应。
