Data from: Monogamy promotes altruistic sterility in insect societies

Monogamy is associated with sibling-directed altruism in multiple animal taxa, including insects, birds, and mammals. Inclusive-fitness theory readily explains this pattern by identifying high relatedness as a promoter of altruism. In keeping with this prediction, monogamy should promote the evolution of voluntary sterility in insect societies if sterile workers make for better helpers. However, a recent mathematical population-genetics analysis failed to identify a consistent effect of monogamy on voluntary worker sterility. Here, we revisit that analysis. First, we relax genetic assumptions, considering not only alleles of extreme effect—encoding either no sterility or complete sterility—but also alleles with intermediate effects on worker sterility. Second, we broaden the stability analysis—which focused on the invasibility of populations where either all workers are fully-sterile or all workers are fully-reproductive—to identify where intermediate pure or mixed evolutionarily-stable states may occur. Third, we consider a broader range of demographically-explicit ecological scenarios relevant to altruistic worker non-reproduction and to the evolution of eusociality more generally. We find that, in the absence of genetic constraints, monogamy always promotes altruistic worker sterility and may inhibit spiteful worker sterility. Our extended analysis demonstrates that an exact population-genetics approach strongly supports the prediction of inclusive-fitness theory that monogamy promotes sib-directed altruism in social insects.在包括昆虫、鸟类和哺乳类在内的多个动物类群中，单配制（monogamy）与同胞导向的利他行为存在关联。广义适合度理论（inclusive-fitness theory）将高亲缘性视为利他行为的促进因素，从而轻松解释了这一现象。按照该理论的预测，若不育工蚁能成为更优秀的协助者，那么单配制应当会推动昆虫社会中自愿不育性状的演化。然而，近期一项基于种群遗传学（population-genetics）的数学分析并未发现单配制对工蚁自愿不育存在一致的影响效应。在此，我们重新审视了该分析：首先，我们放宽了遗传假设，不仅考虑极端效应的等位基因（alleles）——即要么不编码不育、要么编码完全不育——还同时考虑了对工蚁不育具有中等效应的等位基因；其次，我们拓展了原有的稳定性分析——原分析仅聚焦于两种种群状态的可入侵性：即所有工蚁完全不育，或所有工蚁完全可育——以识别可能存在的中等纯合或混合进化稳定状态（evolutionarily-stable states）；第三，我们考虑了更广泛的、与利他性工蚁不繁殖以及更广泛的真社会性（eusociality）演化相关的纳入人口统计学细节的生态场景。我们发现，在不存在遗传约束的情况下，单配制始终会促进利他性工蚁不育，且可能抑制恶意性工蚁不育。我们的拓展分析表明，精确的种群遗传学方法有力支持了广义适合度理论的预测：单配制会推动社会性昆虫的同胞导向利他行为演化。