Fig. 2
A phylogenetic character statement compared to a phenotype description based on the EQ model. The upper line represents the character statement “eye color: red”, following the syntax suggested by Sereno [77], with L1 indicating the (first) locator and V the variable, which together constitute the character part of a character statement. The character state is represented by the value v1, which is one of the possible states defined for the character statement. This phylogenetic character statement can be translated into the EQ statement eye+red, with eye from, e.g., the Mouse Adult Gross Anatomy Ontology (id MA:0000261), representing the locator L1 part of the character and red from PATO (id PATO:0000322) representing the value v1 of the character state. Because PATO organizes quality terms in a nested hierarchy of increasingly differentiated attributes, the reference to red implicitly references also color (id PATO:0000020) and thus the variable V part of the character (cf. [52])