Microbial biodiversity and biogeography

This chapter summarizes the major groups of microorganisms found in high latitude aquatic ecosystems and the methodological approaches used to study their biodiversity. The underlying mechanisms that influence microbial biodiversity, including both the survival and dispersal of microorganisms in polar aquatic environments, are explored. The chapter considers the biogeography of microorganisms (i.e., the distribution of taxa) in polar aquatic ecosystems and presents studies that reveal a degree of endemism. To date, studies have shown that among the microorganisms of polar aquatic habitats, morphological class hides a much greater genetic diversity; the extent of the biodiversity uncovered is proportional to sample effort; the vast majority of biodiversity is as yet uncultivated; cosmopolitan groups are present; and that the key environmental factors controlling microbial distribution are temperature and biotic interactions.