Phylogeography of the Microcoleus vaginatus (Cyanobacteria) from Three Continents – A Spatial and Temporal Characterization

It has long been assumed that cyanobacteria have, as with other free-living microorganisms, a ubiquitous occurrence. Neither the geographical dispersal barriers nor allopatric speciation has been taken into account. We endeavoured to examine the spatial and temporal patterns of global distribution within populations of the cyanobacterium Microcoleus vaginatus, originated from three continents, and to evaluate the role of dispersal barriers in the evolution of free-living cyanobacteria. Complex phylogeographical approach was applied to assess the dispersal and evolutionary patterns in the cyanobacterium Microcoleus vaginatus (Oscillatoriales). We compared the 16S rRNA and 16S-23S ITS sequences of strains which had originated from three continents (North America, Europe, and Asia). The spatial distribution was investigated using a phylogenetic tree, network, as well as principal coordinate analysis (PCoA). A temporal characterization was inferred using molecular clocks, calibrated from fossil DNA. Data analysis revealed broad genetic diversity within M. vaginatus. Based on the phylogenetic tree, network, and PCoA analysis, the strains isolated in Europe were spatially separated from those which originated from Asia and North America. A chronogram showed a temporal limitation of dispersal barriers on the continental scale. Dispersal barriers and allopatric speciation had an important role in the evolution of M. vaginatus. However, these dispersal barriers did not have a permanent character; therefore, the genetic flow among populations on a continental scale was only temporarily present. Furthermore, M. vaginatus is a recently evolved species, which has been going through substantial evolutionary changes

Jacksonvillea apiculata

Two strains of an unusual, filamentous, Geitlerinema-like cyanobacterium inhabiting sandy sediments in Lake Oneida (Jacksonville, Florida) were isolated. These strains possessed a unique combination of specific morphological and molecular characters that enable the establishment of a new monospecific genus on the basis of the type species Jacksonvillea apiculata sp. nov. named in honor of the city of Jacksonville. Morphologically, the species differed from Geitlerinema splendidum and other representatives of the genus Geitlerinema by the presence of spherical structures in the cell walls at cross-walls. Similarly, sequences of the 16S ribosomal RNA gene were below the currently accepted similarity for inclusion into the same genus (i.e. 86% sequence similarity), and were most similar to Desertifilum (88%). To acknowledge the high difference of the Jacksonvillea-Desertifilum clade from members of the family Coleofasciculaceae, we established the new family Desertifilaceae fam. nov., which formed a poorly supported sister clade to some unclear Geitlerinema such the black-band disease strains