| Summary: | The Irano‐Turanian (IT) floristic region is considered an important centre of origin for many taxa. However, there is a lack of studies dealing with typical IT genera that also occur in neighbouring areas. The species-rich monocot genus Gagea Salisb. shows a centre of diversity in IT region and a distribution in adjacent regions, therefore representing a good study object to investigate spatial and temporal relationships among IT region and its neighbouring areas (East-Asia, Euro-Siberia, Himalaya, and Mediterranean). We aimed at (i) testing the origin of the genus and of its major lineages in the IT region, (ii) reconstructing divergence times and (iii) reconstructing colonisation events. To address these problems, sequences of the ribosomal DNA internal transcribed spacer (ITS) region of 418 individuals and chloroplast intergenic spacers sequences (psbA-trnH, trnL-trnF) of 497 individuals, representing 116 species from all sections of the genus and nearly its entire distribution area were analysed. Divergence times were estimated under a random molecular clock based on nrITS phylogeny, which was the most complete data set regarding the representation of species and distribution areas. Ancestral distribution ranges were estimated for the nrITS data set as well as for a combined data set, revealing that Gagea most likely originated in southwestern Asia. This genus first diversified there starting in the Early Miocene. In the Middle Miocene, Gagea migrated to the Mediterranean and to East Asia, while migration into Euro-Siberia took place in the Late Miocene. During the Pleistocene, the Arctic was colonised and Gagea serotina, the most widespread species, reached North America. The Mediterranean basin was colonised multiple times from southwestern Asia or Euro-Siberia. Most of the currently existing species originated during the last 3 Ma. Biogeography of Gagea Appendix including TableS1, Figures S1-S4Includes the information on studied material (voucher, origin and references, origin), cpDNA haplotype (HT) and ...
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