IDENTIFICATION OF APOMORPHIES AND THE ROLE OF GROUNDPATTERNS IN MOLECULAR SYSTEMATICS

Putative apomorphic character states are the only relevant phylogeneti c signal contained in sets of sequence data. Using the sequence positi on as a character, a way to identify putative apomorphies prior to phy logenetic analysis is proposed. It is shown that distance-matrix metho ds use trivial characters. The concept of the asymmetrical split is pr esented for determination of character polarity. It is furthermore arg ued that groundpatterns (node sequences) should be reconstructed prior to the study of relationships between taxa of high phylogenetic age. The 'evolutionary noise' contained in groundpatterns can be illustrate d with a network of distances using a split-decomposition analysis.