Evolution of elaborate parental care: genetic architecture and selection

是什么造就了一个好父母？后代应该如何应对不同的父母策略？父母的目标是为他们的孩子提供一个良好的生活开端，因为父母对子女的照顾可能是其自身生存和繁殖成功的重要决定因素。父母提供照顾的方式可能有很大的差异，从对蛋的大量投资到特殊行为，如准备巢、提供食物或保护后代免受捕食者的伤害。然而，一个领域的高投资(例如，在后代孵化之前投入大量努力，通过对鸡蛋的大量投资)可能会减少对另一个领域的投资潜力(例如，孵化后的努力)。同样，后代在发育过程中最大化获取资源的方式可能会有所不同：例如，花费大量时间或精力向父母乞讨会降低他们花时间独立喂养的能力。因此，很明显，父母的照顾和子女的行为涉及父母和子女表型的多个方面，这些不同方面之间可能存在权衡。然而，令人惊讶的是，到目前为止，关于父母照顾的研究通常只集中在父母和/或子女行为的一个或两个关键方面。因此，我们对所涉及的许多性状之间的联系知之甚少，也不知道它们实际上如何影响后代的生长和存活。最重要的是，为了了解这些关键生活史特征的进化，我们对父母行为的多个方面与后代发育之间的遗传联系了解很少。编码父母提供的某一方面的高比率的基因是否与另一方面的低比率有关？后代是否在基因上遵循某种特定的策略？这些问题不仅对我们理解父母养育的进化至关重要，而且还支撑了当前进化生物学的最大挑战之一：解释了遗传多样性的维持，当时达尔文理论预测，自然选择应该淘汰除最成功的基因以外的所有基因。在不同的行为和策略之间存在这样的“权衡”，没有一个单一的基因在所有方面都是最好的，这为基因变异的其他悖论的持久性提供了一个吸引人的解释。在这个项目中，我们将使用三种不同的实验技术和一个无脊椎动物模型系统--埋头甲虫--来解决我们对父母照料演变的理解中的这些差距。首先，我们使用经典的“育种设计”来确定一系列重要特征(从父母筑巢准备到后代存活)的遗传基础，并解决这样一个问题：父母和后代是否在遗传上被编程为以特定的方式行事？其次，我们进行了一项“选择实验”，在这个实验中，我们考察了亲代和子代性状组合对后代生长的人工选择的进化反应：尤其是，是否有可能为允许后代通过乞讨最大化从父母那里得到的父母-子代特征组合而选择，或者选择有利于能够独立生活的后代的组合？最后，我们用“交叉养育”实验来确定选择在多大程度上有利于父母和子女行为的特定组合：与父母行为相似的父母一起抚养，还是父母行为相似的父母抚养的孩子表现最好，而父母的父母截然不同？我们相信，这三种替代方法与我们自己在行为生态学(PTS)和数量遗传学(LEBK)方面的专业知识相结合，提供了一种独特而强大的手段，大大提高了我们对父母照料中的差异的理解。

What makes a good parent? And how should offspring respond to different parental strategies? Parents aim to provide their young with a good start in life, as the parental care that an offspring experiences can be an important determinant of its own survival and reproductive success. The ways in which parents provide care may vary greatly, ranging from high investment in eggs to specialized behaviours such as the preparation of a nest, provisioning of food or protection of offspring from predators. However high investment in one area (for example, putting in a lot of effort before offspring have hatched through heavy investment into eggs) may reduce potential for investment in another area (for example, post-hatching effort). Similarly, offspring may vary in the ways in which they aim to maximise access to resources whilst developing: for example, spending a lot of time or energy begging from parents will reduce their ability to spend that time feeding independently. It is therefore clear that parental care and offspring behaviour involve multiple aspects of parent and offspring phenotypes, and that there may be trade-offs between these different aspects. However, surprisingly, to date studies of parental care have typically focused on only one or two key aspects of either parental and/or offspring behaviour. We therefore know very little about the associations between the many traits involved, or how they actually affect offspring growth and survival. Most importantly, for an understanding of the evolution of these key life history traits, we have very little understanding of the genetic associations between the multiple aspects of parental behaviour and offspring development. Are the genes that code for high rates of one aspect of parental provisioning associated with low rates of another trait? Are offspring genetically programmed to follow a particular strategy? As well as being critical to our understanding of the evolution of parental care, these questions underpin one of the greatest challenges of current evolutionary biology: explaining the maintenance of genetic diversity, when Darwinian theory predicts that natural selection should weed out all but the most successful genotype. The existence of such 'trade-offs' between different behaviours and strategies, such that no single genotype is best on all counts, provides an appealing explanation for the otherwise paradoxical persistence of genetic variance. In this project we will address these gaps in our understanding of the evolution of parental care using three different experimental techniques and a model invertebrate system, the burying beetle Nicrophorus vespilloides. Firstly, we use a classic 'breeding design' to determine the genetic basis of a suite of important traits (ranging from parental nest preparation through to offspring survival), and to address the question are parents and offspring genetically programmed to behave in a particular way? Secondly, we undertake a 'selection experiment' in which we examine the evolutionary response of suites of parental and offspring traits in response to artificial selection on offspring growth: in particular, is it possible to select either for a combination of parent-offspring traits that allows offspring to maximize what they get out of their parents through begging versus for a combination of traits that favours offspring who can fare independently? Finally, we use a 'cross-fostering' experiment to determine the extent to which selection favours particular combinations of parental and offspring behaviours: do offspring do best when reared with their own parents or with parents with similar behaviour, versus with very different parents? We believe that the combination of these three alternative approaches with our own expertise in behavioural ecology (PTS) and quantitative genetics (LEBK) provides a uniquely powerful means of substantially advancing our understanding of variation in parental care.