Measuring the heritability of sex ratio in a social insect

动物社会行为如何进化的理论是进化生态学的一个基本问题，它假设社会行为受到基因的影响。这个关键的假设很少得到验证，而且人们对社会特征背后的基因知之甚少。在实验中，研究人员将性状进行人工选择，结合现代遗传和基因组技术，可以帮助精确定位和识别这些性状的基因。未来，我的团队将在大黄蜂Bombus terrestris中进行这样的实验，使用性别比例（新蜂后与雄蜂的比例）作为感兴趣的社会特征。虽然进化模型很好地预测了社会性昆虫的性别比例，但与其他社会性特征一样，人们对其遗传基础知之甚少。然而，为了开展这项工作，我们首先需要确定性别比例确实是由遗传变异决定的，也就是说，性别比例是可遗传的，因为不可遗传的性状既不能对自然选择也不能对人工选择作出反应。因此，在提议的工作中，我试图测量土刺的性别比例的遗传性。这个物种非常适合这项工作，因为它简单，每年一次的社会，它对实验室饲养和繁殖的适应性，以及其基因组结构中日益复杂的遗传信息的存在。我将通过比较女王女儿和母亲所生的性别比例来衡量遗传能力。女儿和母亲性别比例之间的正相关关系将建立遗传力（正式估计为该关联回归系数的两倍）。除了解决了进化生态学中的一个基本问题外，这一建议也是新颖的，因为性别比例的遗传性此前还没有在任何群居昆虫中进行过测量。由于这个原因，也因为它应该导致一个未来的项目，也将是新颖的和基础的，拟议的研究应该大大推进该领域。

Theories for how social behaviour evolves in animals, which represents a fundamental issue in evolutionary ecology, assume that social behaviour is influenced by genes. This critical assumption has rarely been tested, and very little is known about the genes underlying social traits. Experiments in which researchers subject traits to artificial selection, combined with modern genetic and genomic techniques, can help pinpoint and identify genes for these traits. In future, my group seeks to conduct such experiments in the bumble bee Bombus terrestris, using sex ratio (the ratio of new queens to males) as the social trait of interest. Although the value of the sex ratio in social insects is well predicted by evolutionary models, as with other social traits very little is known about its genetic basis. However, to conduct this work we first need to establish that sex ratio is indeed underpinned by genetic variation, i.e. is heritable, since non-heritable traits cannot respond to either natural or artificial selection. In the proposed work I therefore seek to measure the heritability of sex ratio in B. terrestris. This species is uniquely suited to the proposed work because of its simple, annual societies, its amenability to laboratory rearing and breeding, and the existence of increasingly sophisticated genetic information on its genomic architecture. I will measure heritability by comparing the sex ratios produced by daughter queens with those produced by their mothers. A positive association between daughter and maternal sex ratios will establish heritability (which is formally estimated as twice the regression coefficient of this association). As well as addressing a fundamental issue in evolutionary ecology, this proposal is novel, because the heritability of sex ratio has not previously been measured in any social insect. For this reason, and because it should lead to a future project that would also be novel and fundamental, the proposed research should substantially advance the field.