QUEEN-WORKER COADAPTATION AND CONFLICT IN A PRIMITIVELY EUSOCIAL BEE

了解家庭内部发生的利益冲突一直是进化生物学研究的一个主要焦点：除非它们在基因上是相同的，否则家庭成员的确切进化利益往往不同。家庭冲突在群居昆虫中得到了特别好的研究，在这些问题上，女王和她的工蚁之间存在潜在的冲突，比如谁应该产卵，后代的性别比是多少，以及女王的任期有多长。然而，虽然现在人们对这些冲突的进化终点知道得很多，但对潜在的遗传结构和女王和工蚁表达的基因之间相互适应的模式却知之甚少。这项提议将调查英国社会汗蜂Lasioglossum marachurum(膜翅目：Halictidae)的蜂王和工蜂之间的相互作用。一种关键的方法将是交叉养育：就在工蚁成年之前，蜂王将在不同的巢之间切换。因为杂交后的蜂王不再与遗传相关的工蚁(通常是它们自己的后代)共用一个巢，所以交叉养育意味着(1)蜂王和工蚁对后代特征的影响可以分开；(2)蜂王和工蚁(现在在单独的巢中)行为之间的任何后续相关性必须反映工蚁从蜂王那里继承的基因，而不是共同环境的影响；(3)蚁后和工蚁的特征之间会产生“不匹配”--在进化冲突中预计会出现的那种不匹配，但通常不能用于研究，因为进化在很大程度上消除了这种不匹配。通过结合交叉培养和DNA指纹图谱来确定每个后代是由蚁后还是工蚁产生的，这项工作将实现以下目标。目标1：测试进化是否导致了蜂王在与新巢中的工蚁的繁殖冲突中获胜的能力，以及工蚁在与无关的蚁后的相同冲突中获胜的能力之间的相关性。目标2：对蜂王是否为了自身利益而操纵工蚁的大小和数量进行第一次直接测试，例如，通过减少工蜂的大小，从而减少工蚁在后代生产上与工蚁竞争的能力。目标3：将蜂后的影响与工蚁对后代大小的影响分开，并从理论上调查潜在的遗传结构。目标4：对帮助膜翅目进化的一个关键假设进行第一次直接测试：即更大的工蚁群体导致更多的雌性偏向后代的性别比。由于工蚁与女王后代的亲缘关系比雄蜂更密切，这种影响可能有助于提供帮助。该研究系统允许在自然选择进行的领域中获得非常大的样本量。总体结果将是迄今为止对蜂王和工蚁共同进化过程的最全面的理解，包括对几个关键假说的第一次测试。将在苏塞克斯大学开展实证性工作，该项目将与项目合作伙伴Mathias Kölliker教授(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).