1. Our Understanding of the Tree of Life Continues to Change Based on New Data

2. Classifying Before Molecular Homology
In the late 1960’s the kingdoms were divided into five kingdoms. (When I was in school, we learned about 5 kingdoms). It soon came to be that the kingdom monera became obsolete and was divided into the domains of Archea and Eubacteria.
Eubacteria contains most bacteria, Archea contains prokaryotes that live in extreme environments, and everything else everything else falls into Eukarya.

3. Horizontal Gene Transfer
Figure 26.21
Horizontal gene transfer is a process in which genes are transferred from one genome to another through mechanisms exchange of transposable elements and plasmids, viral infection, and the fusion of two organisms.
Figure 26.23