Data from: Conditional fetal and infant killing by male baboons

Sexually selected feticide—the death of infants in utero as a result of male behavior—has only rarely been described or analyzed, although it is presumed to be favored by the same selective pressures that favor sexually selected infanticide. To test this hypothesis, we measured the frequency of feticide and infanticide by male baboons of the Amboseli basin in Kenya, and examined which characteristics of a male and his environment made him more likely to commit feticide and/or infanticide. We found a dramatic increase in fetal and infant death rates, but no increase in death rates of 1-2 year-old individuals, following the immigration of males who stood to benefit from feticide and infanticide. Specifically, fetal and infant death rates were highest following immigrations in which: (1) the immigrant male rapidly attained high rank, (2) that male remained consistently resident in the group for at least three months, (3) food availability and social group range overlap was relatively low, and (4) relatively many pregnant females and/or dependent infants were present. Together, these results provide strong evidence for the existence of both sexually selected feticide and infanticide in our population, and they indicate that feticide and infanticide are conditional male behavioral strategies employed under particular circumstances.

性选择杀胎（Sexually selected feticide）——指雄性行为引发的宫内胎儿死亡——此前极少被描述与分析，尽管学界推测其与性选择杀婴（sexually selected infanticide）受相同的选择压力青睐。为验证这一假说，我们对肯尼亚安博塞利盆地雄性狒狒的杀胎与杀婴行为频率进行了测定，并分析了雄性个体及其所处环境的哪些特征会使其更易实施杀胎或杀婴行为。我们发现，在有可能从杀胎、杀婴行为中获益的雄性狒狒迁入种群后，胎儿与幼崽的死亡率显著上升，但1至2岁个体的死亡率并无变化。具体而言，当满足以下条件的雄性迁入后，胎儿与幼崽死亡率达到峰值：（1）迁入雄性迅速获得较高社会地位；（2）该雄性持续定居种群至少三个月；（3）食物可获得性与种群活动范围重叠度相对较低；（4）种群内怀孕雌性或依赖亲代的幼崽数量相对较多。综上，这些结果为我们研究的种群中存在性选择杀胎与杀婴行为提供了有力证据，同时表明杀胎与杀婴是雄性在特定情境下采用的条件性行为策略。