XVI International Botanical Congess

Previous attempts to resolve relationships among the Ulvophyceae have yielded ambiguous results. Current analyses of morphology and 18S rDNA sequences suggest that ulvophycean algae are not monophyletic, but specific results from these data sets differ. Morphological data suggest that the ulvophycean orders are a basal paraphyletic group and that the Ulvales and Ulotrichales clade is the sister group of the Chlorophyceae and Trebouxiophyceae. Analyses of 18S rDNA data, however, suggest that the Caulerpales, Dasycladales and Cladophorales is the sister group of chlorophycean clade. The relative strength of these results and the implications for character evolution will be discussed.