The Prokaryotes

The prokaryotes consist of various thousands of known species to which some order has been applied with the advent of 16S rRNA sequencing. The resulting phylogenetic tree in Figure 1 has been used as an indication of how life begins. To view the two kingdoms in the prokaryotes as primitive is an oversimplification as both the Archaea and the Bacteria are extremely well adapted to their environments. A brief survey of Archaea and Bacteria cannot hope to encompass their diversity and may even give a misguided view in which the Bacteria are predominantly pathogenic or in which Archaea are predominantly thermophilic. However, the best studied Bacteria are pathogenic despite the numerous examples of beneficial species and the best studied Archaea are thermophiles.

                         Figure.  Phylogenetic tree showing the relationship of the Bacteria, Eukarya and Archaea