Phylogeny and biogeography of Artemisia subgenus Seriphidium (Asteraceae: Anthemideae)

Abstract

Artemisia subg. Seriphidium is one of the largest groups within Artemisia, encompassing more than one hundred species, some of them having considerable ecological and economical importance. However, the evolution of subg. Seriphidium has received less attention in comparison to other subgenera of Artemisia, probably, apart from the difficulty of sampling throughout its very large distribution area, because of the low molecular and morphological variability observed in previous studies. Here, we use thorough taxonomic sampling within both Artemisia and subg. Seriphidium to reconstruct the evolutionary history of the subgenus, employing nuclear and plastid DNA sequences as well as various phylogenetic, biogeographic and diversification dynamics tools to analyse the data. Our results show that subg. Seriphidium is not monophyletic, but segregated into two main clades: one large monophyletic group corresponding to the formerly recognised sect. Seriphidium and a second, small clade, phylogenetically distant from the first. Biogeographic and diversification analyses indicate that a rapid radiation of species within sect. Seriphidium occurred in Central Asia during the Miocene-Pliocene transition. The results of our biogeographic analysis suggest that this diversification process started around the Tian-Shan, Pamir and Hindu Kush mountain ranges, subsequently expanding into the Eurasian continent. Finally, we uncovered numerous incongruences between taxonomic and genetic information in several sect. Seriphidium species, which could be explained by morphological uniformity, hybridisation and/or incomplete lineage sorting processes.