The formation of eusocial groups: partner choice, conflict and the role of the market

在群居或合作繁殖的动物群体中，一些个体充当助手，抚养其他个体（蚁后或繁殖者）的后代。例子包括蜜蜂、蚂蚁、裸鼹鼠和猫鼬。这些群体如何以及为什么形成是生物学中的一个关键问题。主要的试验场是所谓的原始群居物种，在这些物种中，蚁后和帮助者在形态上没有区别，所以所有的个体仍然可以选择在群体之外独立繁殖。纸蜂（Polistes）是研究得最好的昆虫系统。在春天，越冬的雌性，被称为奠基者，单独或成群地建立新的巢穴。在多个奠基者的巢穴中，一个“优势”的雌性产卵，而其他的则作为助手，觅食喂养优势的幼虫。然而，尽管有一个完善的理论框架来理解为什么个体会成为帮助者，但群体形成的过程本身却很少被研究。在先前工作的基础上，本提案将结合三个新的操纵实验和DNA分析来研究Polistes的群体形成。这项工作将：(1)测试先前工作中隐含的关键假设：就其他合作伙伴加入而言，创始人有哪些选择，居民之间是否存在团体成员关系的冲突？(2)操纵市场力量——现有群体对潜在参与者的供应——以揭示对社会主要特征的影响，如伙伴转换、帮助努力和群体生产力。(3)检验伴侣选择在决定群体生产力、繁殖分配和合作行为中的重要性。结果将提供对原始群居昆虫群体形成的最全面的理解，并允许对先前的模型和数据进行批判性评估。

In eusocial or cooperatively-breeding groups of animals, some individuals act as helpers, rearing the offspring of other individuals (queens or breeders). Examples include honeybees, ants, naked mole-rats and meerkats. How and why these groups form is a key question in biology. The main testing-grounds are so-called primitively eusocial species, in which queens and helpers are not morphologically differentiated so that all individuals still have the option of independent reproduction outside the group. Paper wasps (Polistes) are the best studied insect system. In spring, overwintered females, known as foundresses, initiate new nests alone or in groups. On multiple-foundress nests, one 'dominant' female lays most of the eggs, while the others act as helpers, foraging to feed the dominant's larvae. However, although there is a well developed theoretical framework for understanding why individuals become helpers, the process of group formation itself has been little studied. Building on previous work, this proposal will combine three novel manipulative experiments with DNA profiling to investigate group formation in Polistes. The work will:(1) Test critical assumptions implicit in previous work: what options do foundresses have, in terms of alternative partners to join, and is there conflict between residents over group membership?(2) Manipulate market forces - the supply of pre-existing groups available to potential joiners - to reveal the effect on major features of eusociality such as partner switching, helping effort and group productivity. (3) Test the importance of partner choice in determining group productivity, partitioning of reproduction and cooperative behaviour.Results will provide the most comprehensive understanding of group formation in a primitively eusocial insect, and allow a critical evaluation of previous models and data.