Hotspots of intraspecific diversity: how are morphologically distinct populations generated and maintained within a species?

种内多样性的热点：一个物种内形态不同的种群是如何产生和维持的？

基本信息

批准号：
NE/P011764/1
负责人：
Beverley Jane Glover
金额：
$ 51.74万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FP011764%2F1
关键词：
Hotspots intraspecific diversity how morphologically

项目摘要

Many species, including humans, show morphological variation. Not all members of the species look the same, and they may vary in any number of traits. The presence of this morphological variation is very important, because it is a source of evolutionary change. Since populations contain individuals with different characteristics, natural selection may work to favour certain forms and repress others, or it may be the case that different forms are successful in different parts of the range of the organism, generating multiple species from a single starting species. In this project we aim to understand how morphological variation within a species is produced genetically, how variation is affected by natural selection resulting from ecological context, and how such variation is maintained when varieties meet. By understanding the production and maintenance of morphological variation we will gain greater insight into how evolution and speciation occur and provide input into models of how different species will respond to the various challenges that might occur as a result of climate change.We have developed a South African daisy species, Gorteria diffusa, as the best model system for this work. Gorteria produces classic "daisy" flowerheads composed of small circular disk florets in the centre and large elongated ray florets round the outside. All the florets are orange but some of the ray florets sometimes produce raised black spots that mimic the fly that pollinates the species. Within Gorteria's range in South Africa it exists as around 15 distinct forms (called morphotypes), each of which has a unique combination of floral traits, such as ray floret number and colour, presence or absence of spots, number of spots, presence and position of highlights in the spot, and presence and position of papillae in the spots. This species therefore provides an excellent example of extreme morphological variation, but is nonetheless easy to collect, grow and work with. The relative immobility of plants removes problems of migration and self-selection of environment. We have established procedures for molecular biological work with Gorteria. We can perturb gene expression using transgenic approaches, a very powerful way of understanding how genes control plant morphology. We have a good understanding of the molecular genetic basis of the development of a single petal spot type. We have also developed a strong collaboration with Dr Allan Ellis, a pollination ecologist at the University of Stellenbosch, South Africa, who will help with this project by providing support in the field.We have already defined how the different morphotypes of Gorteria are related to one another. In this project we will map different aspects of floral morphology and pollinator behaviour onto this phylogenetic tree to understand which direction evolution has taken for each trait and how many times each trait has evolved. Working together in the field, we will quantify the ecological context of each morphotype to understand how selection has favoured different morphologies in different geographic locations, and then test the hypotheses we generate by transplanting plants between different sites. We will then define the molecular evolution underpinning this morphological evolution - analysing what changes to key genes have allowed the visible changes we observe. Finally, to explain why morphologies don't merge into a continuum when populations meet, we will analyse the morphology and genetic structure of Gorteria populations at the places where different morphotypes meet, and explore post-zygotic isolation between morphotypes.Taken together, these data will give us an integrated eco-evo-devo understanding of how this enormous variation in flower types exists within Gorteria, providing us with insight into how species radiate so rapidly in the Cape Flora and other biodiversity hotspots.

许多物种，包括人类，都表现出形态变异。并非该物种的所有成员看起来都一样，并且它们在许多特征上可能有所不同。这种形态变异的存在非常重要，因为它是进化变化的根源。由于种群包含具有不同特征的个体，自然选择可能会偏爱某些形式并抑制其他形式，或者可能是不同形式在生物体范围的不同部分取得成功，从单个起始物种产生多个物种。在这个项目中，我们的目标是了解物种内的形态变异是如何通过遗传产生的，变异是如何受到生态背景下的自然选择的影响，以及当品种相遇时如何维持这种变异。通过了解形态变异的产生和维持，我们将更深入地了解进化和物种形成是如何发生的，并为不同物种如何应对气候变化可能出现的各种挑战的模型提供输入。非洲雏菊品种 Gorteria diffusa 是这项工作的最佳模型系统。 Gorteria 产生经典的“雏菊”花头，由中心的小圆盘小花和外围的大细长舌状花组成。所有的小花都是橙色的，但一些射线小花有时会产生凸起的黑点，模仿为该物种授粉的苍蝇。在南非的 Gorteria 分布范围内，它以大约 15 种不同的形式（称为形态型）存在，每种形式都有独特的花性状组合，例如舌状花的数量和颜色、斑点的存在或不存在、斑点的数量、存在和位置斑点中的亮点，以及斑点中乳头的存在和位置。因此，该物种提供了极端形态变异的绝佳范例，但仍然易于收集、种植和使用。植物的相对固定性消除了迁移和环境自我选择的问题。我们已经制定了与 Gorteria 进行分子生物学工作的程序。我们可以使用转基因方法扰乱基因表达，这是理解基因如何控制植物形态的一种非常有效的方法。我们对单一花瓣斑点类型发育的分子遗传基础有了很好的了解。我们还与南非斯泰伦博斯大学的授粉生态学家 Allan Ellis 博士建立了强有力的合作，他将通过提供现场支持来帮助完成该项目。我们已经定义了 Gorteria 的不同形态类型与彼此。在这个项目中，我们将把花卉形态和传粉者行为的不同方面映射到这个系统发育树上，以了解每个性状的进化方向以及每个性状进化了多少次。我们将在现场共同努力，量化每种形态类型的生态背景，以了解选择如何有利于不同地理位置的不同形态，然后通过在不同地点之间移植植物来测试我们产生的假设。然后，我们将定义支撑这种形态进化的分子进化——分析关键基因的哪些变化导致了我们观察到的可见变化。最后，为了解释为什么当种群相遇时形态不会融合成一个连续体，我们将分析不同形态型相遇处的 Gorteria 种群的形态和遗传结构，并探索形态型之间的合子后隔离。综合起来，这些数据将使我们对 Gorteria 内花卉类型的巨大差异如何存在有一个综合的生态-进化-发展了解，使我们深入了解物种如何在弗洛拉角和其他生物多样性中如此迅速地辐射热点。