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。染色中稳定的多态性为研究进化过程提供了机会，包括自然选择、基因流动和野生环境中的遗传漂移。在某些情况下，颜色的变化是个体在生理、行为和其他复杂特征上差异的外部指标。颜色和其他性状之间的这种遗传相关性对于维持种群内的变异可能是重要的。在某些情况下，这种相关性是由于紧密连锁的多个基因，即所谓的超基因，但在另一些情况下，复杂的多态似乎有非常简单的遗传基础。在这里，我们将研究木老虎蛾Arctia ants aginis的遗传相关性。雄性有黄色或白色的后翼，但这些变种在行为、信息素、免疫反应和防御化学方面也不同。相反，雌性幼虫的后翼色表现出连续的变化，这与幼虫的警示色呈负相关。该系统在遗传分析方面具有许多优点，易于大量饲养，并在野外得到了良好的研究。关于男性多态的初步工作已经确定了一个控制形态差异的狭窄基因组区域，只包含六个基因。在这里，我们将通过基因表达和基因敲除实验来确定导致黄/白色多态的基因。接下来，我们将测试不同形态之间的复杂性状是否作为主要黄/白基因座的多效性效应而变化，或者它们是否代表可能保持连锁不平衡的其他基因座的变异。我们还将探索成虫和幼虫颜色特征的遗传结构，这些特征表现出更连续的变化。在这里，我们将利用已经可以用于基因分析的大型家系。我们将利用我们在芬兰的Co-I Johanna Mappes进行额外的育种和家庭表型鉴定。最后，我们将利用已有的大量野生捕获个体来研究野生物种的遗传变异模式。特别是，我们将在控制多态和变色表型的基因座上测试平衡选择的标志。我们还将测试控制多个品系的基因座之间的关联模式(连锁不平衡)。总而言之，这个项目为开发新的进化遗传系统提供了一个令人兴奋的机会。木老虎蛾在田间和实验室已经得到了很好的研究。关于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，我们知道很多。然而，尽管遗传分析具有许多优点，包括易于大量饲养和相对较小的基因组，但到目前为止，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。这个项目有可能开发一个令人兴奋的新教科书例子，在这个例子中，可以通过从基因型到表型再到野外适应性来研究进化力量。

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.