Social evolution in ground and twig-nesting bees

利他主义是指个体牺牲自己的繁殖来帮助其他个体繁殖的行为。利他主义的基因是如何在处于健康劣势的人群中传播的？这个谜题通常用亲缘选择来解释：利他主义者确实牺牲了个人繁殖，但通过帮助培养共享基因的近亲来弥补这一损失。亲缘选择表明，当利他主义者把他们的合作行为目标放在抚养亲属上时，利他主义可以在人群中传播，这些亲属就像他们自己的后代一样，也携带着利他主义者的基因。利他主义的动物生活在社会中，其中一些最著名的是群居昆虫，包括许多种类的蜜蜂。在两个蜜蜂群体中，汗蜂和木蜂，行为是高度可变的，从完全孤独的蜜蜂，在没有其他蜜蜂帮助的情况下抚养他们的孩子，到平等主义或“公共”社会，所有的个体都平等合作，到由自私的蜂后和利他的工蜂组成的基于种姓的社会。我的研究旨在解释蜜蜂社会中的这种变化。我也在研究为什么有些女性个体比其他女性更可能是利他主义者。我正在测试几种理论来解释利他主义和蜜蜂社会的形式。这些理论包括亲缘选择，雌性质量假说，认为小，弱或不育的雌性更有可能成为帮助者而不是繁殖者，以及环境质量假说，认为蜜蜂更有可能在蜂群更多产的环境中形成社会，如果成年蜜蜂合作。50多年来，生物学家一直在积累对蜜蜂社会多样性的观察。这里提出的研究将使我和我的学生能够解决有关动物社会行为的重要问题，这些问题几十年来一直困扰着进化生物学家，但直到最近才得以研究。

Altruism is behaviour in which an individual sacrifices its own reproduction in order to help other individuals reproduce. How do genes for altruism spread through populations when they are at a fitness disadvantage? The puzzle is often explained by kin selection: altruists do sacrifice personal reproduction, but more than make up for it by helping to raise close relatives which share their genes. Kin selection suggests that altruism can spread through populations when altruists target their cooperative behaviour towards raising relatives, which, like their own offspring, also carry the altruist's genes. Altruistic animals live in societies, and some of the best known are those of social insects, including many species of bees. In two bee groups, the sweat bees and carpenter bees, behaviour is highly variable, from bees that are completely solitary and raise their young with no help from other bees, to egalitarian or 'communal' societies where all individuals are equally cooperative, to caste-based societies composed of selfish queens and altruistic workers. My research is geared towards explaining this variation in bee societies. I am also studying why some individual females are more likely to be altruistic than others. I am testing several theories to explain both altruism and the forms of bee societies. These theories include kin selection, the female quality hypothesis, which suggests that small, weak or infertile females are more likely to become helpers than breeders, and the environmental quality hypothesis, which suggests that bees are more likely to form societies in environments where colonies are more productive if adults cooperate. For more than 50 years, biologists have been accumulating observations on bee social diversity. The studies proposed here will allow me and my students to address important questions about animal social behaviour, questions that have preoccupied evolutionary biologists for decades, but which until recently, have not been amenable to study.