A postgenomic approach to the role of odour and gustatory receptors in speciation

所有动物都依赖于对环境中挥发性和非挥发性化学物质的感知（分别是气味和味觉）。它们利用这些信息来寻找食物、躲避捕食者、寻找配偶和其他重要功能。化学感觉不同于其他感觉，因为它们需要对每种化合物或化合物类别作出反应的特定受体。最近，在很大程度上通过基因组测序项目，已经确定了编码气味和味觉受体的基因类别，并且它们的特征正在迅速进行。它们很可能是理解在许多情况下对化学信息的识别和处理的关键。气味和味觉信号在许多动物的物种形成中发挥着核心作用，通过它们在栖息地和配偶选择方面的功能，可以说是早熟和生殖隔离的两种主要形式。因此，气味和味觉受体基因类别的识别为采取系统方法研究物种形成过程中这一关键组成部分的遗传基础提供了一个令人兴奋的机会。在这个项目中，我们将利用基因组信息和黑腹果蝇亚群的物种来调查选择的气味和味觉受体位点在物种内部和物种之间的差异。我们将比较物种之间的序列差异和物种内部的变异水平，以检测在自然选择下迅速进化的位点。我们将在物种间杂交的重组自交系中测试气味和味觉受体位点与关键行为特征（如配偶和栖息地选择）之间的关联。这将证实候选基因座在关键行为步骤中的作用。我们将在同一组菌株中检查基因表达，以测试改变表达模式和潜在新功能的位点。这将为结构和表达修饰在适应性进化中的相对作用这一长期存在的问题提供系统的答案，并指出候选的“物种形成基因”。该项目是在该领域具有互补专业知识的三个实验室之间的合作。除了对物种形成遗传学的无与伦比的洞察力外，该项目还将提供有关这些迷人而重要的基因进化的新数据，这对许多其他物种和环境（包括害虫和疾病媒介控制）的研究具有重要意义。

All animals rely on sensing volatile and non-volatile chemicals in their environment (odour and gustatory senses, respectively). They use this information for detecting food, avoiding predators, finding mates and other crucial functions. The chemical senses are unlike other senses in that they require specific receptors for each compound or class of compounds to which they respond. Recently, in large part through genome sequencing projects, classes of genes coding for odorant and gustatory receptors have been identified and their characterisation is now proceeding rapidly. They may well be the key to understanding the recognition and processing of chemical information in many contexts. Odour and gustatory signals have central roles in speciation in many animals through their functions in both habitat and mate choice, arguably the two primary forms of premating reproductive isolation. The identification of odorant and gustatory receptor gene classes thus provides an exciting opportunity to take a systematic approach to the genetic basis of this key component of the speciation process. In this project, we will use genomic information and species of the Drosophila melanogaster subgroup to survey selected odorant and gustatory receptor loci for variation within and between species. We will compare sequence divergence between species with levels of variation within species to detect loci that have evolved rapidly under natural selection. We will test for associations between odorant and gustatory receptor loci and key behavioural traits, such as mate and habitat choice, in recombinant inbred lines of crosses between species. This will confirm the roles of candidate loci in critical behavioural steps. We will examine gene expression in the same set of strains to test for loci that have altered expression patterns and so potentially novel functions. This will provide a systematic answer to the longstanding question of the relative roles of structural and expression modifications in adaptive evolution as well as pointing to candidate 'speciation genes'. The project is a collaboration between three laboratories with complementary expertise in this area. As well as the unparalleled insight into the genetics of speciation, the project will provide new data on the evolution of these fascinating and important genes with implications for their study in many other species and contexts including pest and disease vector control.