Journey to the west: Migration patterns of the riparian montane genus Myricaria

Myricaria Desv. (Tamaricaceae) is a genus of riparian plants found in montane regions throughout Eurasia. We present molecular phylogenies covering the entire Eurasian range of the genus using the chloroplast interspacer region psbA-trnH, the chloroplast region trnL-trnF, and the nuclear ribosomal Internal Transcribed Spacer (ITS). Biogeographical analyses of the DNA sequencing data based on Takhtajan's Floristic Provinces using a Bayesian Binary Markov Chain Monte Carlo reconstruction show that the origin of Myricaria is the Tibetan Floristic Province, specifically in the Qinghai-Tibetan Plateau. A molecular clock analysis was also performed. We estimate that the crown age of Myricaria is around 22.8 Ma and that the common ancestor of all European Myricaria occurred around 8.8 Ma ago. By covering the entire native range of the genus, our analyses confirm previous hypotheses on the origin and migration patterns of Myricaria, namely a central Asian centre of origin, followed by a westward migration to Europe via the central Asian mountain ranges, the Caucasus, and Eastern Europe. The divergence times and migration routes of Myricaria are remarkably similar to that of the genus Hippophae L.