The Current Conventions for Designating Microbial Species – Strengths and Limitations

RECONCILING MICROBIAL SYSTEMATICS & GENOMICS Microorganisms are fantastically diverse, both genetically and phenotypically. The amount and depth of genetic diversity represented among the named microbial species is greater than that represented among the animals and plants combined. If the distinctions and testing in use today could be applied to all microorganisms (even those that cannot be grown in the laboratory), the number of microbial species easily could reach into the billions. Moreover, the current statistical approaches all tend to underestimate microbial diversity. Linear metrics, in particular, are likely to lead to very large errors because they fail to account for population size, age of clades, and variation in rates of nucleotide substitution. Hence, microbial diversity is vast, and the currently available techniques for estimating the extent of this diversity probably under represent it.