Understanding the genetic control of a complex polymorphism

动物的颜色千差万别，可以适应多种功能，包括伪装、警告、性信号和体温调节。稳定的多态性提供了一个机会来研究进化过程，包括自然选择、基因流动和遗传漂变在野外的作用。在某些情况下，颜色的变化是个体之间生理、行为和其他复杂特征差异的外部指标。这种颜色和其他性状之间的遗传相关性对于维持种群内的变异是很重要的。在某些情况下，这种相关性是由于紧密连接的多个基因，即所谓的超基因，但在其他情况下，复杂多态性似乎具有非常简单的遗传基础。本文将研究木虎蛾的遗传相关性。雄性有黄色或白色的后翅，但这些形态在行为、信息素、免疫反应和防御化学方面也有所不同。雌蜂后翅颜色呈连续变化，与幼虫警告色呈负相关。该系统具有遗传分析的优点，易于大量饲养和野外研究。对男性多态性的初步研究已经确定了一个控制形态差异的狭窄基因组区域，该区域仅包含6个基因。在这里，我们将通过基因表达和基因敲低实验来确定导致黄/白多态性的基因。接下来，我们将测试不同变体之间的复杂性状差异是否作为主要黄/白基因座的多效性效应而变化，或者它们是否代表其他基因座可能在连锁不平衡中保持的变异。我们还将探索在成虫和幼虫颜色性状中表现出更连续变化的权衡的遗传结构。在这里，我们将利用已经可用于遗传分析的大型系谱。将与我们在芬兰的Co-I Johanna Mappes一起进行额外的家庭育种和表型分析。最后，我们将利用已有的大量野生捕获的个体来研究野生遗传变异的模式。特别是，我们将在控制多态和可变颜色表型的位点上测试平衡选择的特征。我们还将测试控制多个性状的位点之间的关联模式（连锁不平衡）。总之，这个项目为开发一个新的进化遗传系统提供了一个令人兴奋的机会。木虎蛾已经在野外和实验室得到了很好的研究。我们对它与捕食者和生物环境的相互作用，以及它的行为和生态生理都了解得很多。然而，尽管遗传分析有许多优点，包括易于大量饲养和相对较小的基因组，但迄今为止很少进行遗传分析。在这里，我们将探索该系统中关键性状的遗传基础，并在遗传水平上探索自然选择在野生种群中的作用。这个项目有潜力开发一个令人兴奋的新教科书范例，其中进化力量可以研究从基因型到表型再到野外的适应性。

Animals are hugely varied in their colouration, which can be adapted for a multiplicity of functions including camouflage, warning, sexual signals and thermoregulation. Stable polymorphisms in colouration offer an opportunity to study evolutionary processes including natural selection, gene flow and genetic drift acting in the wild. In some cases, variation in colour is an external indicator of differences between individuals in their physiology, behaviour and other complex traits. Such genetic correlations among colouration and other traits can be important for the maintenance of variation within populations. In some cases, such correlations are due to multiple genes in tight linkage, so-called supergenes, but in other cases complex polymorphisms seem to have a very simple genetic basis. Here we will study genetic correlations in the wood tiger moth, Arctia plantaginis. Males have either yellow or white hindwings, but these morphs also differ in behaviour, pheromones, immune responses and defensive chemistry. In contrast, females show continuous variation in hindwing colour, which is negatively correlated with larval warning colour. The system has many advantages for genetic analysis, being tractable to rear in large numbers and well-studied in the wild. Preliminary work on the male polymorphism has identified a narrow genomic region that controls morph differences, containing just six genes. Here we will identify the gene responsible for the yellow/white polymorphism using gene expression and gene knockdown experiments. Next, we will test whether the complex traits that differ between morphs vary as pleiotropic effects of the major yellow/white locus, or whether they represent variation at other loci perhaps maintained in linkage disequilibrium. We will also explore the genetic architecture of trade-offs in adult and larval colour traits that show more continuous variation. Here, we will take advantage of large pedigrees that are already available for genetic analysis. Additional breeding and phenotyping of families will be carried out with our Co-I Johanna Mappes in Finland. Finally, we will take advantage of large numbers of wild caught individuals already available to study patterns of genetic variation in the wild. In particular, we will test for signatures of balancing selection at loci controlling polymorphic and variable colour phenotypes. We will also test for patterns of association (linkage disequilibrium) between loci controlling multiple traits.In summary, this project offers an exciting opportunity to develop a new evolutionary genetic system. The wood tiger moth is already well studied in the field and laboratory. We know a great deal about its interaction with predators and with the biotic environment, as well as its behaviour and eco-physiology. However, despite many advantages for genetic analysis including ease of rearing in large numbers and relatively small genome, little genetic analysis has been carried out to date. Here we will explore the genetic basis for key traits in this system and explore the action of natural selection in wild populations at a genetic level. This project has the potential for developing an exciting new text-book example, in which evolutionary forces can be studied through from genotype to phenotype to fitness in the wild.