QUEEN-WORKER COADAPTATION AND CONFLICT IN A PRIMITIVELY EUSOCIAL BEE

理解家族内部发生的利益冲突一直是进化生物学研究的主要焦点：除非他们在基因上是相同的，否则个体家庭成员的确切进化利益往往是不同的。在群居昆虫中，家庭冲突已经得到了很好的研究，蜂王和工蜂之间存在着潜在的冲突，比如谁应该产卵，后代的性别比例是多少，以及蜂王的任期长短。然而，虽然现在对这些冲突的进化终点了解很多，但对潜在的遗传结构和蚁后和工蜂表达基因之间相互适应的模式知之甚少。本研究将研究英国社会汗蜂Lasioglossum malachurum（膜翅目：蜂科）中蜂王与工蜂之间的相互作用。一个关键的方法是交叉抚养：就在工蚁成年之前，蚁后将在不同的巢穴之间交换。因为交叉培养的蚁后不再与有遗传关系的工蜂（通常是它们自己的后代）共享一个巢穴，所以交叉培养意味着(1)蚁后和工蜂对后代特征的影响可以分开；(2)蚁后和工蜂（现在在不同的巢穴中）行为之间的任何后续相关性必须反映工蜂从蚁后那里遗传的基因，而不是共同环境的影响；(3)蚁后和工蚁特征之间产生了“不匹配”——这种不匹配是在持续的进化冲突中预期的，但通常无法用于研究，因为进化在很大程度上消除了它们。通过结合交叉培育和DNA指纹来确定每个后代是由蚁后还是工蜂所生，这项工作将实现以下目标。目标1：测试进化是否导致了蚁后在与新巢工蜂的繁殖冲突中获胜的能力与工蜂在与不相关的蚁后的相同冲突中获胜的能力之间的相关性。目标2：进行第一次直接测试，看看蚁后是否通常为了自己的利益而操纵工蜂的大小和数量，例如，通过减少工蜂的大小，从而降低工蜂与蚁后竞争后代的能力。目的3：分离蜂后和工蜂对后代关键性状体型的影响，并从理论上研究潜在的遗传结构。目标4：对膜翅目昆虫进化的一个关键假设进行第一次直接检验：一个更大的工蜂群体导致后代的性别比例更偏向于雌性。由于工蜂与蚁后的雌性后代的亲缘关系比与雄性后代的亲缘关系更密切，因此这种效应可能会促进帮助。该研究系统允许在自然选择起作用的领域获得特别大的样本量。总体结果将是迄今为止对蚁后-工蜂协同进化过程最全面的理解，包括对几个关键假设的首次测试。实证工作将在苏塞克斯大学进行，该项目将与项目合作伙伴Mathias教授Kölliker（瑞士巴塞尔大学）合作。

Understanding the conflicts of interest that occur within families has been a major focus of research in evolutionary biology: unless they are genetically identical, the precise evolutionary interests of individual family members often differ. Family conflicts have been particularly well studied in social insects, where there is potential conflict between the queen and her workers over questions such as who should lay the eggs, what sex-ratio of offspring to produce, and the length of tenure of the queen. However, while much is now known about the evolutionary endpoint of these conflicts, little is known about the underlying genetic architecture and the pattern of reciprocal adaptation between queen- and worker-expressed genes. This proposal will investigate queen-worker interactions in the UK social sweat bee Lasioglossum malachurum (Hymenoptera: Halictidae). A key method will be cross-fostering: just before workers reach adulthood, queens will be switched between nests. Because cross-fostered queens no longer share a nest with genetically related workers (which would normally be their own offspring), cross-fostering means that (1) queen and worker influences on offspring characteristics can be separated; (2) any subsequent correlations between the behaviour of a queen and her workers (now in separate nests) must reflect genes inherited by workers from queens rather than effects of the common environment; (3) 'mismatches' between queen and worker characteristics are generated - mismatches of the kind expected during on-going evolutionary conflict, but not normally available to study because evolution has largely eliminated them.By using a combination of cross-fostering, and DNA fingerprinting to determine whether each offspring was produced by queen or workers, the work will achieve the following objectives.Objective 1: Test whether evolution has led to a correlation between a queen's ability to prevail in reproductive conflicts with the workers in her new nest, and the ability of her workers to prevail in the same conflicts with an unrelated queen. Objective 2: Carry out the first direct test of whether queens normally manipulate worker size and number in their own interests, for example by reducing worker size and therefore a worker's ability to compete with the queen over offspring production.Objective 3: Separate queen influences from worker influences on body size, a key offspring trait, and investigate the underlying genetic architecture theoretically.Objective 4: Carry out the first direct test of a key hypothesis for the evolution of helping in Hymenoptera: the hypothesis that a larger group of workers leads to a more female-biased sex-ratio of offspring. Because workers are more closely related to female- than male offspring of the queen, such an effect could facilitate helping. The study system allows exceptionally large sample sizes to be obtained in the field, where natural selection operates. The overall result will be the most comprehensive understanding to date of the process of queen-worker coevolution, including the first tests of several key hypotheses. Empirical work will be carried out at the University of Sussex, and the project will involve collaboration with Project Partner Prof Mathias Kölliker (University of Basel, Switzerland).