Data from: Retracted: Experimental evidence that maternal corticosterone controls adaptive offspring sex ratios

THIS ARTICLE HAS BEEN RETRACTED 1. Sex allocation theory has received considerable attention, yet the mechanism(s) by which mothers skew offspring sex ratios remain unknown. In birds, females are the heterogametic sex, which potentially gives them control of whether gametes will be male or female. How females might control the sex of the gamete is unclear, but one possibility is that variation in steroid hormones may mediate this process. 2. We experimentally altered circulating levels of corticosterone in female Gouldian finches (Erythrura gouldiae), a species that demonstrates both extreme stress responses and extreme offspring sex ratio biases when breeding with a low-quality (genetically-incompatible) partner. 3. During egg production, individual females received both corticosterone and metyrapone (a corticosterone-synthesis inhibitor) implants, in random order, to induce both high and low levels of circulating stress hormones (within physiological limits). 4. We found that females with elevated corticosterone levels produced male-biased sex ratios, but when the same females were treated with metyrapone they produced female-biased offspring sex ratios. 5. These stress responses are adaptive because females constrained to breeding with low-quality males can substantially increase their fitness by overproducing sons. Changes in maternal corticosterone levels during stressful situations, such as the quality of a breeding partner, may provide an endocrine mechanism that can be exploited for strategic sex allocation.本文已被撤回。1. 性别分配理论（sex allocation theory）已受到广泛关注，但母体调控后代性别比例的具体机制仍未明确。在鸟类中，雌性为异配性别（heterogametic sex），这使其理论上具备控制配子性别生成的能力。目前学界尚未阐明雌性调控配子性别的具体方式，但一种潜在可能性为：类固醇激素（steroid hormones）的水平变异可介导这一过程。2. 我们对雌性Gouldian雀（Erythrura gouldiae）的循环皮质酮（corticosterone）水平开展了实验干预——该物种在与低质量（遗传不相容）配偶繁殖时，既会表现出强烈的应激反应，也会出现极端的后代性别比例偏差。3. 在产卵阶段，我们为个体雌鸟先后随机植入皮质酮与美替拉酮（metyrapone，一种皮质酮合成抑制剂），以在生理范围内分别诱导其循环应激激素达到高水平与低水平状态。4. 研究结果显示，皮质酮水平升高的雌鸟所产后代性别比例偏雄性，而同一批雌鸟接受美替拉酮处理后，所产后代性别比例则偏雌性。5. 这类应激反应具有适应性意义：当雌鸟被迫与低质量雄鸟交配时，通过过量产雄可显著提升自身的进化适合度（fitness）。当雌鸟面临配偶质量这类应激情境时，其体内皮质酮水平的变化或许提供了一种内分泌机制，可用于实现策略性性别分配。