Linking adaptive evolution and reproductive barriers in budding yeasts

物种如何形成是生物学中的一个基本问题。虽然物种通常被认为是独立的类别，但情况并非总是如此。繁殖障碍阻止物种产生合适的后代，它们是保持物种差异的主要机制。例如，驴和马可以交配生出骡子，这是两者的杂交，但骡子是不育的，不能自己生育后代。这种不育是一种生殖障碍，因为骡子是一条“死胡同”——它们无法进一步传递自己的基因。有时候混血儿能够存活并繁殖，它们的后代也会有很大的变异。结果可能是积极的，使物种能够在极端条件下生存，或优化农业或生物技术过程所需的特性。相反，它可能会导致新的疾病出现。气候变化导致不稳定的环境条件，增加了这种杂交事件发生的可能性。我的目的是了解导致生殖障碍和杂交的因素，以及这些因素存在的原因。生殖障碍主要有两种类型：外在障碍，由生物体与环境的相互作用产生；内在障碍，由生物体自身产生。外在障碍和内在障碍是否经常有相同的潜在原因尚不清楚，这正是我想要找出的。我将利用一种成熟的模式生物的力量，即微生物酵母，酿酒酵母及其近亲。这些酵母以其在生物技术中的作用而闻名，包括啤酒和葡萄酒的发酵，但它们也得到了充分的研究，并且易于在实验室中操作。为了了解这些酵母的繁殖障碍，我将使用三种具有不同最佳生长温度（外在障碍）的物种。这些物种之间的杂交可以生长，但大部分是不育的（内在障碍）。我将确定这两种障碍的遗传原因，看看它们是否相同。首先，我会找到在不同温度下负责生长的基因。除了告诉我们外在的屏障外，这些基因对生物技术的发展也很有用，因为在某些温度下优化生长是至关重要的。其次，我将确定基因组中负责杂交不育的区域。这些类型的区域被认为对所有物种的存在都很重要，但已知的例子很少。然后，我将确定对温度的反应和杂交不育是否涉及相同的基因，并在生物物种存在的基础因素之间建立联系。这项研究将在埃克塞特大学进行，这是一个研究微生物进化的卓越中心。我将置身于一个高度协作的研究环境中，与来自高度相关学科的世界知名专家共享实验室空间和资源。为了扩大我的研究的影响，我还将得到埃克塞特研究真菌病原体的世界级研究人员小组的支持。最后，我将与国际同事Gianni Liti博士（法国）和Sarah Otto教授（加拿大）合作。Gianni Liti博士是确定复杂性状背后的基因方法的专家，Sarah Otto教授是进化生物学数学建模的世界专家。气候变化是联合国公认的超越国界的全球紧急情况。通过了解新出现的真菌病原体，了解生物体如何应对不断变化的气候，特别是新创造的杂交品种，可以影响农业和健康。通过整合分子生物学和进化生物学之间的信息，我将推进生物科学发现的前沿。

How species form is a fundamental question in biology. While species are often thought of as discrete categories, this is not always the case. Reproductive barriers prevent species from being able to make fit offspring, and they are the main mechanism that keeps species distinct. For example, donkeys and horses can mate to produce mules, a hybrid between the two, but mules are sterile and cannot produce offspring themselves. This sterility is a reproductive barrier because the mules are a "dead end" - they are not able to pass on their genes any further. Sometimes hybrids can survive and reproduce, and their offspring can be highly variable. The results can be positive, allowing species to survive extreme conditions or optimising a desirable trait for agriculture or biotechnological processes. Conversely, it can allow new diseases to emerge. Climate change, leading to unstable environmental conditions, increases the likelihood of such hybridisation events to occur. I aim to understand the factors contributing to reproductive barriers and hybridization, and why these factors exist. There are two main types of reproductive barriers: extrinsic, resulting from the organisms' interactions with the environment, and intrinsic, resulting from the organisms themselves. It is unknown whether extrinsic and intrinsic barriers often have the same underlying causes, and this is what I want to find out. I will harness the power of a well-established model organism, the microbial yeast Saccharomyces cerevisiae and its close relatives. These yeasts are best known for their role in biotechnology, including beer and wine fermentation, but they are also well-studied and easy to manipulate in the lab. To understand reproductive barriers in these yeasts, I will use three species that have different optimal growth temperatures (extrinsic barrier). Hybrids between these species can grow, but are largely sterile (intrinsic barrier). I will determine the genetic reasons for these two barriers to see if they are the same. First, I will find the genes responsible for growth in different temperatures. Beyond informing us about extrinsic barriers, these genes will be useful for the development of biotechnology, where optimizing growth at certain temperatures can be critical. Second, I will determine regions of the genome responsible for hybrid sterility. These types of regions are expected to be important for the existence of species of all kinds, but there are few known examples. I will then determine whether the same genes are involved in both response to temperature and hybrid sterility, and make connections between factors that underlie the existence of biological species.This research will be carried out at the University of Exeter, a centre of excellence for studying microbial evolution. I will be embedded in a highly collaborative research environment, sharing laboratory space and resources with world-renowned experts from highly relevant disciplines. To broaden the impacts of my research, I will also be supported by a world-class group of researchers in Exeter who study fungal pathogens. Finally, I will collaborate with international colleagues Dr Gianni Liti (France), an expert on methods for determining the genes underlying complex traits, and Prof Sarah Otto (Canada), a world expert on mathematical modelling of evolutionary biology. Climate change is a UN recognized global emergency that transcends borders. Understanding how organisms respond to changing climate, especially newly created hybrids, can impact agriculture and health through understanding of emerging fungal pathogens. By integrating information between molecular and evolutionary biology, I will advance the frontiers of bioscience discovery.