When homoplasy is not homoplasy: dissecting trait evolution by contrasting composite and reductive coding

The conceptualization and coding of characters is a difficult issue in phylogenetic systematics, no matter which inference method is used when reconstructing phylogenetic trees or if the characters are just mapped onto a specific tree. Complex characters are groups of features that can be divided into simpler hierarchical characters (reductive coding), although the implied hierarchical relational information may change depending on the type of coding (composite vs reductive). Up to now, there is no common agreement to either code characters as complex or simple. Phylogeneticists have discussed which coding method is best, but have not incorporated the heuristic process of reciprocal illumination to evaluate the coding. Composite coding allows to test 1) if several characters were linked resulting in a structure described as a complex character or trait, or 2) if independently evolving characters resulted in the configuration incorrectly interpreted as a complex character. We propose tha...