Molecular evidence for ancient relicts of arctic‐alpine plants in E ast A sia

Following climate cooling at the end of the T ertiary, arctic‐alpine plants attained most of their extant species diversity. Because E ast A sia was not heavily glaciated, the importance of this region as a location for the long‐term persistence of these species and their subsequent endemism during the P leistocene was proposed in early discussions of phytogeography. However, this hypothesis remains to be fully tested. Here, we address this hypothesis by elucidating the phylogenetic history of P hyllodoce ( E ricaceae). A phylogenetic tree based on multiple nuclear loci revealed that Phyllodoce nipponica was not derived from widespread species such as the arctic‐alpine Phyllodoce caerulea , but rather represented an independent lineage sister to the clade of widespread relatives. Molecular dating indicated a mid‐ P leistocene divergence of P . nipponica . These findings exclude the hypothesis that P . nipponica was derived from an arctic‐alpine species that extended its range southwards during recent glacial periods. Instead, our results support the hypothesis that P . nipponica is an ancestral species which persisted in the Japanese archipelago during the mid‐ and late Pleistocene. Our findings demonstrate support for the early proposal and shed light on the importance of the Japanese archipelago for the evolution and persistence of arctic‐alpine species.