Phylogenetics and Biogeography of Lilium ledebourii from the Hyrcanian Forest

Abstract

Lilium ledebourii (Baker) Boiss is one of the most endangered lilies, restricted to only a few small and fragmented areas in the Hyrcanian forest. This study aimed at evaluating the taxonomy of this unique Iranian lily and reconstructing divergence time from other species of the genus Lilium to address the role of this region in its diversification. Phylogenetic trees based on nuclear ITS and chloroplastic matK strongly supported the monophyly of the genus Lilium and division into subclades hardly matching prior morphological classifications. Biogeographic analyses using S-DIVA revealed East Asia as the ancestral range from where Lilium presented a multidirectional expansion towards North America, West-Central Asia, North Asia, and Europe. Diverging from ancestral Lilium during the beginning of Eocene (50 Ma; 95% HDP: 68.8–36.8). Specific members of Lilium colonized Iran (Western Asia) separated from the Clade IV (West-Central Asia and Europe lineage), and then yielded the Iranian L.ledebourri. Accordingly, the north of Iran appears to have promoted both long-term persistence and migration of Lily species from Asia to the Europe.