Microbial eukaryote diversity and evolution in extraordinary environments

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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.