Microbial eukaryote diversity and evolution in extraordinary environments

自由生活的原生动物代表了大部分物种和更高的真核生物群（即比细菌更复杂的一切），然而，我们对它们的生物多样性的理解远远落后于其他真核生物，例如动物，植物，真菌，藻类和寄生虫。 该项目旨在了解原生动物在特殊栖息地的生物多样性，这些栖息地通常被认为几乎没有真核生物：缺氧栖息地（几乎没有氧气）和高盐栖息地（盐浓度是正常海水的3-10倍）。 我们将从这些栖息地培养小型自由生活的原生动物，并使用基因序列的比较来确定它们彼此之间的进化关系，以及与以前从这些栖息地和其他环境中分离的原生动物的进化关系。 我们的目标是了解原生动物是否已经成为适应这些环境在进化史上的几次或多次。 一些生物体将代表新的高等分类群（可能相当于新的“门”），并将使用电子显微镜以及进一步的DNA序列表征和分析进行详细描述。 在缺氧原生动物的情况下，我们还将直接从环境中获得特定群体的DNA序列，并将其与培养物种的序列进行比较：这将使我们能够确定我们培养的物种是否是自然界中这些生物体实际多样性的良好代表或不良代表。 在原生动物的情况下，从高盐栖息地，我们看到了一个奇怪的现象，其中一些原生动物生活在极端盐水看起来完全一样的原生动物在海洋样品中发现。 我们将比较这些“相同”的海洋和高盐原生动物的多个分离株的基因序列，以确定它们实际上在遗传上有多相似，以及它们是否根据它们生长最好的盐度分离成不同的进化组。 这将有助于理解一个物种到底是什么（如果有的话）复杂的，可能是无性微生物的世界。

Free-living protozoa represent a large fraction of species and higher groups of eukaryotic organisms (i.e. everything more complex than bacteria), however, our understanding of their biodiversity lags way behind that of other eukaryotes, e.g. animals, plants, fungi, algae, and parasites. This project seeks to understand the biodiversity of protozoa in extraordinary habitats that are often considered to have very few eukaryotic organisms in them at all: anoxic habitats (were there is little or no oxygen), and hypersaline habitats (where the concentration of salt is 3-10 times that in normal seawater). We will culture small free-living protozoa from these habitats, and use comparisons of gene sequences to determine their evolutionary relationships to each other, and to previously isolated protozoa from these habitats and from other environments. We aim to understand whether protozoa have become adapted to these environments on few occasions or many occasions in evolutionary history. Some of the organisms will represent new higher taxa (maybe the equivalent of new 'phyla'), and will be described in detail using electron microscopy, and further DNA sequence characterisation and analysis. In the case of anoxic protozoa we will also obtain DNA sequences for particular groups directly from the environment, and compare them to the sequences from cultured species: This will allow us to determine whether the species we have in culture are a good representation, or a poor representation, of the actual diversity of these organisms present in nature. In the case of protozoa from hypersaline habitats we see a strange phenonemon where some of the protozoa that live in extremely saline water look exactly the same as protozoa that are found in marine samples. We will compare gene sequences from multiple isolates of thse 'identical' marine and hypersaline protozoa to determine how genetically similar they actually are, and whether they segregate into distinct evolutionary groups based on the salinity they grow best at. This will contribute to understanding what a species really is (if anything) the world of complex, possibly asexual microbes.