Relating to the evolutionary relationships of organisms. A phylogenetic tree, for example, refers to a graphic representation of the evolutionary history of organisms described in a branching pattern. Such trees are made with a variety of information, but for bacteria, a powerful technique is to use the similarity of DNA sequences to deduce relatedness. An assumption is that close relatives share more DNA similarity than distant ones. However, there are complications with this method, which is described in detail in the last part of the lab.