A phylogeny of Delphinieae (Ranunculaceae) shows that Aconitum is nested within Delphinium and that Late Miocene transitions to long life cycles in the Himalayas and Southwest China coincide with bursts in diversification

Abstract

The tribe Delphinieae (Ranunculaceae) comprises two species-rich genera, Aconitum and Delphinium, the latter including Consolida and Aconitella. The 650-700 species are distributed in Eurasia and North America; three species occur on tropical African mountains. Maximum likelihood analyses of 2088 aligned nucleotides of plastid and nuclear sequences obtained from up to 185 species of Delphinieae from throughout the geographic range (plus relevant outgroups) show that three short-lived (facultative annual or biennial) Mediterranean species belonging to Delphinium subgenus Staphisagria are the sister clade to all other Delphinieae, implying that Staphisagria needs to be raised to genus status if Delphinium and Aconitum are to become mutually monophyletic. Molecular clock dating suggests an origin of the sampled Delphinieae in the Early Oligocene (c. 32.3 Ma) and expansion to North America of Aconitum and Delphinium around 3.3 and 2.9 Ma ago, respectively; the East African Mts. were reached by long-distance dispersal some 2.4 Ma ago, coincident with the major uplift of the East African Rift system. The ancestral growth form of the Delphinieae could not be reconstructed, but Late Miocene bursts in diversification rates in the Himalayan and southwestern Chinese clades of Aconitum and Delphinium appear to be associated with transitions from short-lived to long-lived life histories.