XVI International Botanical Congess

When attempting to combine morphological data with large molecular data sets, problems of taxon definition, character extrapolation, and inapplicable structural form can affect homology assessment. However, based on the often weak branch support present in molecular trees, it is clear that morphological characters potentially can have a dramatic effect on cladistic results. We propose that problems in homology assessment for morphological characters are usually no greater, and often less severe than problems encountered with molecular data. With the use of NONA (Goloboff) and the parsimony ratchet (Nixon), very large combined matrices can be quickly analyzed and relative levels of homoplasy in molecular and morphological data can be compared.