Molecular phylogeography of four endemic S agittaria species ( A lismataceae) in the S ino‐ J apanese F loristic R egion of E ast A sia

To reveal the role of climate oscillations of the Q uaternary in forming the contemporary plant diversity in the temperate S ino‐ J apanese F loristic R egion of mainland C hina, we assess the phylogeographical patterns of four S agittaria species in the region using sequence data from plastid DNA non‐coding regions ( psbA‐trnH , the rpl16 intron and trnC‐ycf6 ) and the internal transcribed spacers of nuclear ribosomal DNA (nr ITS ). Based on both datasets, the divergence time among the four studied species was estimated to fall in the L ate T ertiary (plastid DNA : 7.1–13.7  M ya; ITS : 11.1–16.1  M ya). The ancestral distribution analyses revealed that regions with a great diversity in topography, climate and ecological conditions, e.g. the H engduan M ountains, C entral C hina and E ast C hina, were the areas where the endemics originated. Mismatch distribution analyses revealed that each species had experienced a range expansion in response to Q uaternary climatic oscillations. Our findings contradict the hypothesis of Q uaternary origins of the endemic S agittaria spp.; we support the view that modern species in the N orthern H emisphere originated mostly during the Tertiary. Range expansion may have profoundly modified the current distribution ranges of S agittaria species in the S ino‐ J apanese F loristic R egion.  © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society , 2016, 180 , 6–20.