Am Nat. 2020 Oct;196(4):487-500. doi: 10.1086/710210. Epub 2020 Sep 10.
AbstractEvolution of adaptation requires predictability and recurrence of functional contexts. Yet organisms live in multifaceted environments that are dynamic and ever changing, making it difficult to understand how complex adaptations evolve. This problem is particularly apparent in the evolution of adaptive maternal effects, which are often assumed to require reliable and discrete cues that predict conditions in the offspring environment. One resolution to this problem is if adaptive maternal effects evolve through preexisting, generalized maternal pathways that respond to many cues and also influence offspring development. Here, we assess whether an adaptive maternal effect in western bluebirds is influenced by maternal stress pathways across multiple challenging environments. Combining 18 years of hormone sampling across diverse environmental contexts with an experimental manipulation of the competitive environment, we show that multiple environmental factors influenced maternal corticosterone levels, which, in turn, influenced a maternal effect on aggression of sons in adulthood. Together, these results support the idea that multiple stressors can induce a known maternal effect in this system. More generally, they suggest that activation of general pathways, such as the hypothalamic-pituitary-adrenal axis, may simplify and facilitate the evolution of adaptive maternal effects by integrating variable environmental conditions into preexisting maternal physiological systems.
摘要 适应的进化需要功能环境的可预测性和重现性。然而，生物生活在多方面的环境中，这些环境是动态的且不断变化的，这使得理解复杂的适应如何进化变得困难。这个问题在适应性母性行为的进化中尤为明显，因为人们通常认为适应性母性行为需要可靠和离散的线索来预测后代环境中的条件。解决这个问题的一个方法是，如果适应性母性行为是通过对许多线索做出反应并影响后代发育的预先存在的、通用的母性行为途径进化而来的。在这里，我们评估了在西部蓝鸟中，一种适应性母性行为是否受到多种挑战性环境中母性应激途径的影响。我们结合了 18 年来在不同环境背景下的激素采样，并对竞争环境进行了实验操作，结果表明，多种环境因素影响了母鸟皮质酮水平，而皮质酮水平又反过来影响了母鸟对雄性后代成年期攻击性的影响。总的来说，这些结果支持了这样一种观点，即多种胁迫因素可以在这个系统中引发已知的母性行为。更一般地说，它们表明，一般途径的激活，如下丘脑-垂体-肾上腺轴，可以通过将可变的环境条件整合到预先存在的母性生理系统中，简化和促进适应性母性行为的进化。
