Social evolution in ground and twig-nesting bees

利他主义是一种行为，在这种行为中，一个人牺牲了自己的繁衍，以帮助其他人繁衍后代。当人群处于健康劣势时，利他主义基因是如何在人群中传播的？这个谜题通常可以通过亲属选择来解释：利他主义者确实牺牲了个人的生殖，但更多的是通过帮助抚养拥有相同基因的近亲来弥补这一点。亲属选择表明，当利他主义者将他们的合作行为目标定为抚养亲属时，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。无私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--汗蜂和木工蜂中，行为差异很大，从完全与世隔绝、在没有其他蜜蜂帮助的情况下抚养后代的蜜蜂，到所有个人都平等合作的平等主义或“公社”社会，再到由自私的女王和无私的工人组成的种姓社会。我的研究旨在解释蜜蜂社会中的这种变异。我还在研究为什么一些女性个体比其他女性更有可能利他主义。我正在测试几种理论，以解释利他主义和蜜蜂社会的形式。这些理论包括亲属选择，即雌性质量假说，它表明身材矮小、虚弱或不育的雌性更有可能成为帮手，而不是繁殖者；以及环境质量假说，它表明，如果成年蜜蜂合作，蜜蜂更有可能在蜂群更多的环境中结成群落。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关于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，还不适合研究。

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.