Phylogenetic relationships of bryophytes inferred from nuclear-encoded rRNA gene sequences

We investigate phylogenetic relationships among hornworts, liverworts and mosses, and their relationships to other green plant groups, by analysis of nucleotide variation in complete 18s rRNA gene sequences of three green algae, two hornworts, seven liverworts, nine mosses, and six tracheophytes. Parsimony and maximum-likelihood analyses yield a single optimal tree in which the hornworts are resolved as the basal group among land plants, and the liverworts and mosses are sister taxa that together form the sister clade to the tracheophytes. This phylogeny is internally robust as indicated by decay indices and by comparison (using both parsimony and likelihood criteria) to topologies representing five alternative hypotheses of bryophyte relationships. We discuss some possible reasons for differences between the phylogeny inferred from the rRNA data and those inferred from other character sets.