An Example in Phylogenetic Research
The following table contains observations (fictitious) that were carried out on 7 species of fish and one species that was chosen as the sister group to the group (=the closest relative to the group) that we want to study.
I - Polarization Using the Outgroup Comparison.
In this example, the sister group (SG) will be used for the outgroup comparison. This comparison will enable you to polarize the state of each of the characters that you have found. When a character state is present in the outgroup, it is coded "0".
When this state is also present in a member of the ingroup (the group studied), it is also coded "0". If a state is different from that observed within the ingroup, it is apomorphic and must be coded "1" (when that character is binary: 0, 1) or "1" or "2" when that character displays three states (0, 1, 2).
