Figure 1.

The character-state data model used in evolutionary comparative analysis. The character-state data model is illustrated here with an example showing members of a protein family, with a single set of labels for Operational Taxonomic Units, 2 phylogenies, and 3 types of characters (modified from [5]). The biological entities to be compared— whether genes, species, individuals, or some other unit— are known as “OTUs” or “Taxa”. Each OTU may be characterized as having a “state” for a given “character”, e.g., the OTU C_elegans_17537797 has the state “A” (Alanine) for the 2nd amino acid character. Phylogenetic trees (typically, directional, acyclic, singly-linked graphs in which no node has more than one ancestor) connect all the OTUs, representing their descent from a common ancestor.

Stoltzfus et al. BMC Research Notes 2012 5:574   doi:10.1186/1756-0500-5-574
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