University Program in Genetics and Genomics, Duke University, Durham, North Carolina, USA.
Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA.
Am J Biol Anthropol. 2023 Apr;180(4):618-632. doi: 10.1002/ajpa.24686. Epub 2023 Jan 9.
Pregnancy failure represents a major fitness cost for any mammal, particularly those with slow life histories such as primates. Here, we quantified the risk of fetal loss in wild hybrid baboons, including genetic, ecological, and demographic sources of variance. We were particularly interested in testing the hypothesis that hybridization increases fetal loss rates. Such an effect would help explain how baboons may maintain genetic and phenotypic integrity despite interspecific gene flow.
We analyzed outcomes for 1020 pregnancies observed over 46 years in a natural yellow baboon-anubis baboon hybrid zone. Fetal losses and live births were scored based on records of female reproductive state and the appearance of live neonates. We modeled the probability of fetal loss as a function of a female's genetic ancestry (the proportion of her genome estimated to be descended from anubis [vs. yellow] ancestors), age, number of previous fetal losses, dominance rank, group size, climate, and habitat quality using binomial mixed effects models.
Female genetic ancestry did not predict fetal loss. Instead, the risk of fetal loss is elevated for very young and very old females. Fetal loss is most robustly predicted by ecological factors, including poor habitat quality prior to a home range shift and extreme heat during pregnancy.
Our results suggest that gene flow between yellow and anubis baboons is not impeded by an increased risk of fetal loss for hybrid females. Instead, ecological conditions and female age are key determinants of this component of female reproductive success.
妊娠失败是任何哺乳动物的主要适应代价，尤其是对于那些生活史缓慢的物种，如灵长类动物。在这里，我们量化了野生杂交狒狒胎儿丢失的风险，包括遗传、生态和人口统计学方面的差异来源。我们特别感兴趣的是检验杂交增加胎儿丢失率的假设。这种效应可以帮助解释为什么狒狒可以在种间基因流动的情况下保持遗传和表型的完整性。
我们分析了在自然黄狒狒-努比亚狒狒杂交区观察到的 46 年期间 1020 次妊娠的结果。胎儿丢失和活产是根据雌性生殖状态的记录和活产幼崽的出现来评分的。我们使用二项混合效应模型，将胎儿丢失的概率作为女性遗传背景（估计其基因组中源自努比亚（与黄狒狒相比）祖先的比例）、年龄、以前的胎儿丢失次数、优势等级、群体大小、气候和栖息地质量的函数进行建模。
女性遗传背景并不能预测胎儿丢失。相反，非常年轻和非常年老的雌性的胎儿丢失风险增加。胎儿丢失最可靠地由生态因素预测，包括在栖息地发生变化之前的恶劣栖息地质量和怀孕期间的极端高温。
我们的结果表明，黄狒狒和努比亚狒狒之间的基因流动并没有因杂交雌性的胎儿丢失风险增加而受到阻碍。相反，生态条件和雌性年龄是决定这一雌性生殖成功组成部分的关键因素。
