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离散的类别，但情况并不总是如此。生殖障碍使物种无法产生合适的后代，这是使物种保持独特的主要机制。例如，驴和马可以交配产生骡子，这是两者之间的杂交，但骡子是不育的，不能自己繁殖后代。这种不孕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，杂交种可以存活和繁殖，它们的后代可能非常不同。结果可能是积极的，允许物种在极端条件下生存，或者优化农业或生物技术过程中理想的特征。相反，它可能会导致新的疾病出现。气候变化导致环境条件不稳定，增加了此类杂交事件发生的可能性。我的目标是了解导致生殖障碍和杂交的因素，以及为什么这些因素存在。生殖障碍主要有两种类型：外在的，由生物体与环境的相互作用产生的；内在的，由有机体本身产生的。目前尚不清楚外在障碍和内在障碍是否往往具有相同的根本原因，这也是我想要找出的。我将利用一种久负盛名的模式生物--微生物酵母酿酒酵母及其近亲的力量。这些酵母菌最为人所知的是它们在生物技术中的作用，包括啤酒和葡萄酒发酵，但它们也得到了充分的研究，很容易在实验室进行操作。为了了解这些酵母的繁殖障碍，我将使用三种具有不同最适生长温度的物种(外部障碍)。这些物种之间的杂交可以生长，但很大程度上是不育的(内在障碍)。我将确定这两个障碍的遗传原因，看看它们是否相同。首先，我将找到在不同温度下负责生长的基因。除了告诉我们外在障碍外，这些基因还将对生物技术的发展有用，在生物技术中，在特定温度下优化生长可能是至关重要的。其次，我将确定导致杂交不育的基因组区域。这些类型的区域预计对所有种类的物种的存在都很重要，但已知的例子很少。然后，我将确定是否相同的基因参与了对温度和杂交不育的反应，并将生物物种存在的因素之间联系起来。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一个世界级研究人员小组的支持，他们研究真菌病原体。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的方法专家，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，了解生物如何应对气候变化，特别是新创造的杂交生物，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.