Microbial eukaryote diversity and evolution in extraordinary environments

自由生活的原生动物代表了很大一部分物种和较高类别的真核生物(即比细菌更复杂的一切)，然而，我们对它们的生物多样性的了解远远落后于其他真核生物，如动物、植物、真菌、藻类和寄生虫。这个项目试图了解在通常被认为几乎没有真核生物的特殊生境中原生动物的生物多样性：缺氧生境(几乎没有氧气)和高盐生境(那里的盐浓度是正常海水中的3-10倍)。我们将在这些栖息地培养小型自由生活的原生动物，并通过比较基因序列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出来的原生动物的进化关系。我们的目标是了解原生动物在进化史上是否在很少的情况下或在许多情况下适应了这些环境。其中一些生物将代表新的更高的类群(可能相当于新的“门”)，并将使用电子显微镜和进一步的DNA序列特征和分析进行详细描述。就缺氧原生动物而言，我们还将直接从环境中获得特定群体的DNA序列，并将它们与培养物种的序列进行比较：这将使我们能够确定我们在培养中的物种是否很好地代表了自然界中这些生物的实际多样性。在来自高盐度生境的原生动物的例子中，我们看到了一种奇怪的现象，其中一些生活在极端咸水中的原生动物看起来与在海洋样本中发现的原生动物完全相同。我们将比较这些“相同”的海洋和高盐度原生动物的多个分离株的基因序列，以确定它们实际上在基因上有多相似，以及它们是否根据它们生长最好的盐度划分为不同的进化群。这将有助于理解一个物种到底是什么(如果有的话)，那就是复杂的、可能是无性的微生物世界。

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.