Age and biogeography of major clades in Liliales.

A robust phylogeny of 40 genera and all seven families of the Liliales based on rbcL sequences was dated by the mean branch-length method of Bremer and Gustafsson and by Sanderson's nonparametric rate smoothing. The basal node was set to 82 million years (my) from the results of a previous more extensive dating involving all monocots. Confidence intervals for the age estimates were generated by bootstrap analysis. The results indicate that four well-supported clades of Liliales date back to the Cretaceous ∼65 million years ago (mya), Campynemataceae, Melanthiaceae, Smilacaceae + Liliaceae, and Alstroemeriaceae + Luzuriagaceae + Colchicaceae. Aspects of historical biogeography were investigated by dispersal-vicariance analysis. Several dispersal and vicariance events were found to coincide with Late Cretaceous-Early Tertiary changes in continental interconnections. The study contains the first published sequence of Campynemanthe, supporting the Campynemataceae as a monophyletic group.