Paradoxes of biodiversity, phylogeny, and taxonomy of cyanobacteria

Abstract

The biodiversity of cyanobacteria is paradoxical since these bacteria vary in cytological characters although are metabolically uniform. Cyanobacterial phylogeny is also paradoxical as the structural genes of rRNA are too conservative for a large phylum. On the paradoxical evolutionary tree, neighbors have strongly contrasting phenotypes, while objects with similar phenotypes demonstrate a heterological structure of 16S rDNA. The systematics of cyanobacteria is paradoxical, too, since it is logically contradictory: on the one hand, phylum BX Cyanobacteria generally is separated on molecular-biological grounds. On the other hand, in accordance with the traditional botanical algorithm used in classification of blue-green algae, this phylum is artificially subdivided into morphological groups (ultrastructural characters are taken into account only in rare cases). A unique trait of the taxonomy of cyanobacteria (with rare exceptions, e.g., Cyanobacterium stanieri) is its general nonusage of the category of species. The species epithet is replaced by a stain index (e.g., Anabaena PCC 7122).