Evolutionary diversification and adaptation to novel environments in Navarretia (Polemoniaceae)

Phylogenetic relationships in Navarretia were examined using morphological data, and DNA sequence data from nuclear ribosomal DNA internal transcribed spacers. Analyses of molecular and morphological datasets produced similar consensus trees. A combined analysis resulted in increased resolution and stronger bootstrap support for most clades. Results support the hypothesis that sections Mitracarpium and Navarretia are monophyletic, with somewhat weaker support for a third monophyletic group consisting of sections Aegochloa and Masonia. Evolutionary rate heterogeneity among sections is evident. An early radiation is suggested for the Aegochloa-Masonia clade, in contrast to a relatively late radiation of ephemeral pool species (including the single South American member of the genus) in section Navarretia. No such radiation of taxa is evident following three separate instances of adaptation to serpentine