School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK.
Biol Lett. 2020 Mar;16(3):20190764. doi: 10.1098/rsbl.2019.0764. Epub 2020 Mar 18.
The 'haplodiploidy hypothesis' argues that haplodiploid inheritance in bees, wasps, and ants generates relatedness asymmetries that promote the evolution of altruism by females, who are less related to their offspring than to their sisters ('supersister' relatedness). However, a consensus holds that relatedness asymmetry can only drive the evolution of eusociality if workers can direct their help preferentially to sisters over brothers, either through sex-ratio biases or a pre-existing ability to discriminate sexes among the brood. We show via a kin selection model that a simple feature of insect biology can promote the origin of workers in haplodiploids without requiring either condition. In insects in which females must found and provision new nests, body quality may have a stronger influence on female fitness than on male fitness. If altruism boosts the quality of all larval siblings, sisters may, therefore, benefit more than brothers from receiving the same amount of help. Accordingly, the benefits of altruism would fall disproportionately on supersisters in haplodiploids. Haplodiploid females should be more prone to altruism than diplodiploid females or males of either ploidy when altruism elevates female fitness especially, and even when altruists are blind to sibling sex.
“单倍二倍性假说”认为，在蜜蜂、黄蜂和蚂蚁中，单倍二倍性遗传产生了亲缘关系的不对称性，这种不对称性促进了雌性的利他主义进化，因为雌性与其后代的亲缘关系不如与其姐妹的亲缘关系密切（“超级姐妹”亲缘关系）。然而，人们普遍认为，只有当工蜂能够优先将帮助指向姐妹而不是兄弟时，亲缘关系的不对称性才能驱动社会性的进化，这可以通过性别比例偏差或预先存在的在后代中辨别性别的能力来实现。我们通过一个亲缘选择模型表明，昆虫生物学的一个简单特征可以促进单倍二倍性中工蜂的起源，而无需满足上述任何条件。在雌性必须建立和提供新巢穴的昆虫中，身体质量对雌性的适合度可能比对雄性的适合度有更强的影响。如果利他主义提高了所有幼虫兄弟姐妹的质量，那么姐妹从获得相同数量的帮助中获益可能会比兄弟更多。因此，在单倍二倍性中，利他主义的好处将不成比例地落在超级姐妹身上。当利他主义特别提高雌性适合度时，与双倍体雌性或任一倍性的雄性相比，单倍体雌性应该更倾向于利他主义，即使利他主义者对兄弟姐妹的性别一无所知。
