A phylogenetic tree maker is a computer program that allows a user to input data about a group of organisms. The program then analyses the data and determines how the various organisms are related. It displays this information in the form of a phylogenetic tree. Phylogenetic trees are very similar to family trees. However, they depict the relationships among various species rather than the relationships between family members.
Phylogenetic trees can have different resolutions. For example, a researcher working with a small group of primitive mollusks may produce a phylogenetic tree that only includes a handful of species, while another researcher may be considering the relationships of a large group of organisms, such as insects, and produce a phylogenetic tree with thousands of individual species.
Often, scientists investigating phylogeny include a species or group of species that are distantly related to the group being studied. This is called an “outgroup comparison.” For example, if a researcher is studying primates, the primary group he is working with includes humans, chimpanzees and gorillas, among others. To try to understand the relationships among the primates, he may use rodents as an outgroup. This helps to provide a backbone to which the computer program attaches the primate phylogenetic tree.