Fourie Nicolaas H, Jolly Clifford J, Phillips-Conroy Jane E, Brown Janine L, Bernstein Robin M
Biobehavioral Branch, Intramural Research Program, National Institute of Nursing Research, National Institutes of Health, Room 2N104, 10 Center Drive, Bethesda, MD, 20892, USA,
Primates. 2015 Jul;56(3):259-72. doi: 10.1007/s10329-015-0469-z. Epub 2015 Apr 23.
Male olive (Papio anubis) and hamadryas (P. hamadryas) baboons have distinctive sociobehavioral and physical characteristics. In the Awash National Park, Ethiopia, a hybrid population at the contact zone between these two species, exhibits heterogeneous sociobehavioral and physical characteristics. The ambiguity of the hybrid social environment and disruption of parental stress genotypes may be sources of physiological stress for hybrids. We examined levels of chronic stress among males of the three populations and tested the prediction that chronic cortisol levels would be higher among the hybrids. Animals were captured, sampled, and released during the wet season, and a hair sample was taken for assay. Cortisol was extracted from 182 hair samples with methanol and quantified by ELISA. We included age, age class, rainfall variation, and species affiliation in models examining variation in hair cortisol levels. Species and age significantly contributed to models explaining variation in hair cortisol. Infant hypercortisolism was observed in all three groups, and a decline in cortisol through juvenile and adolescent stages, with a subsequent rise in adulthood. This rise occurred earliest in hamadryas, corroborating other evidence of the precocious development of hamadryas baboons. As expected, hybrids had significantly elevated hair cortisol compared with olive baboons and hamadryas, irrespective of age, except for very young animals. Infant hypercortisolism was also less pronounced among hybrids. Species differences and age-related differences in cortisol levels suggest a dysregulated cortisol phenotype in hybrids, and possibly reflect some form of hybrid disadvantage. More work will be required to disentangle the effects of genetic factors and the social environment.
雄性东非狒狒（Papio anubis）和阿拉伯狒狒（P. hamadryas）具有独特的社会行为和身体特征。在埃塞俄比亚的阿瓦什国家公园，这两个物种接触区域的杂交种群表现出异质的社会行为和身体特征。杂交社会环境的模糊性以及亲本应激基因型的破坏可能是杂交种生理应激的来源。我们研究了这三个种群雄性的慢性应激水平，并检验了杂交种慢性皮质醇水平会更高的预测。在雨季捕获、采样并放生动物，采集毛发样本进行检测。用甲醇从182份毛发样本中提取皮质醇，并通过酶联免疫吸附测定法进行定量。在研究毛发皮质醇水平变化的模型中，我们纳入了年龄、年龄组、降雨变化和物种归属。物种和年龄对解释毛发皮质醇变化的模型有显著贡献。在所有三个组中都观察到婴儿高皮质醇血症，皮质醇在幼年和青少年阶段下降，随后在成年期上升。这种上升在阿拉伯狒狒中出现得最早，这证实了阿拉伯狒狒早熟发育的其他证据。正如预期的那样，除了非常年幼的动物外，杂交种的毛发皮质醇水平与东非狒狒和阿拉伯狒狒相比显著升高，与年龄无关。杂交种中的婴儿高皮质醇血症也不太明显。皮质醇水平的物种差异和年龄相关差异表明杂交种的皮质醇表型失调，可能反映了某种形式的杂交劣势。需要更多的工作来厘清遗传因素和社会环境的影响。
