Figure 1.

Cluster diagram of 867 prokaryotic genomic DNA sequences compared pair-wise using hexanucleotide-based genomic signatures. 867 prokaryotic genomic DNA sequences were compared pair-wise with hexanucleotide-based genomic signatures. Hierarchical clustering was performed on the resulting 867 × 867 correlation matrix using average linkage and Euclidean distance. The cluster diagram was grouped into different segments, Groups 1-7, based on the cluster-tree which reflected how the prokaryotic DNA sequences compared pair-wise. Lighter colors mean higher correlation scores, and thus closer similarity between the compared genomes. The multi-colored horizontal bar on top indicates each chromosome's respective phylum, while the vertical red and blue coloured bar shows AT/GC content, where red means GC content larger than 50% and blue AT content larger than 50%. Groups 5 and 7 are mainly populated with free-living, GC rich, prokaryotes with diverse metabolic capabilities. Groups 1 and 3 consist predominantly of AT rich and host-associated archaea and bacteria, while group 2 and 6 consisted mainly of larger host-associated γ-Proteobacteria. Group 4, was the smallest and most dissimilar group, consisting of many extremophiles.