Department of Biology, University of Western Ontario, London, ON, Canada, N6A 5B7.
J Exp Biol. 2012 Sep 15;215(Pt 18):3207-17. doi: 10.1242/jeb.068965. Epub 2012 Jun 12.
Variation in the prenatal and postnatal environments can have long-term effects on adult phenotype. In humans and other animals, exposure to stressors can lead to long-term changes in physiology. These changes may predispose individuals to disease, especially disorders involving energy metabolism. In addition, by permanently altering metabolic rates and energy requirements, such effects could have important fitness consequences. We determined the effects of early-life food restriction and corticosterone (CORT) treatment on growth and adult body size, body composition (assessed via quantitative magnetic resonance) and metabolic rates in the song sparrow, Melospiza melodia. Nestlings were hand-raised in captivity from 3 days of age. Treatments (ad libitum food, food restriction or CORT treatment) lasted from day 7 to day 60. Both experimental treatments had sex-specific effects on growth. In the nestling period, CORT-treated males weighed more than controls, whereas CORT-treated females weighed less than controls. Food-restricted males weighed the same as controls, whereas food-restricted females weighed less than controls. Both experimental treatments also had sex-specific effects on standard metabolic rate (SMR). Females exposed to food restriction or CORT treatment during development had higher SMRs in adulthood than control females, but neither stressor affected SMR in males. There were no effects of either treatment on adult body size, body composition (lean or fat mass) or peak metabolic rate. Therefore, early-life stress may have sex-specific programming effects on metabolic rates and energy expenditure in song sparrows. In addition, both treatments affected nestling growth in a manner that exaggerated the typical sex difference in nestling mass, which could provide male nestlings with a competitive advantage over their sisters when developing in a poor-quality environment.
产前和产后环境的变化会对成年表型产生长期影响。在人类和其他动物中，暴露于应激源会导致生理上的长期变化。这些变化可能使个体易患疾病，尤其是涉及能量代谢的疾病。此外，通过永久改变代谢率和能量需求，这些影响可能对适应度产生重要影响。我们确定了早期生活中食物限制和皮质酮（CORT）处理对鸣禽黑顶麻雀生长和成年体型、体成分（通过定量磁共振评估）和代谢率的影响。雏鸟从 3 天大时开始在人工饲养环境中由人工饲养。处理（自由采食、食物限制或 CORT 处理）从第 7 天持续到第 60 天。两种实验处理都对生长有性别特异性影响。在育雏期，CORT 处理的雄性比对照重，而 CORT 处理的雌性比对照轻。食物限制的雄性与对照相同，而食物限制的雌性比对照轻。两种实验处理也对标准代谢率（SMR）有性别特异性影响。在发育过程中暴露于食物限制或 CORT 处理的雌性成年后的 SMR 高于对照雌性，但两种应激源都没有影响雄性的 SMR。两种处理都没有对成年体型、体成分（瘦体重或脂肪量）或峰值代谢率产生影响。因此，早期生活应激可能对鸣雀的代谢率和能量消耗有性别特异性编程影响。此外，两种处理都以夸大幼鸟质量典型性别差异的方式影响幼鸟的生长，这可能为在劣质环境中发育的雄性幼鸟提供相对于其姐妹的竞争优势。
