PHYLOGENIES CAN REFLECT GENEALOGY AND AMOUNT OF CHANGE
By comparing the inferred rRNA sequences (or those of any other appropriate molecule) it is possible to estimate the historical branching order of the species, and also the total amount of sequence change. An example of a 16S rRNA-based phylogenetic tree showing the three (identified) Domains of life - Bacteria, Archaea and Eucarya - is below. In this tree, lineages diverge from a common ancestral lineage on the far left. The lengths of the individual lines reflect the amount of sequence change (note that some lineages have modified the gene sequence substantially more than others, and thus have accumulated longer total branch lengths).