Fig. 2: Chronogram of east Asian mandarin citrus speciation and biogeography in the Ryukyu Arc and mainland Japan.
From: Diversification of mandarin citrus by hybrid speciation and apomixis
a Population divergence times of C. ryukyuensis (2.2–2.8 Mya) and two subspecies of mainland Asian mandarins (C. reticulata): common mandarin and mangshanyeju (1.4–1.7 Mya). Extant common mandarins are recent admixtures with both mangshanyeju and pummelos. b Geological history of the Ryukyu Arc and evolutionary origins of east Asian citrus during four representative time periods: (1) initial radiation of citrus during the late Miocene20 with subsequent dispersal to regions including Mangshan of the Nanling mountain range. The exact arrival time of primitive mandarins at Mangshan cannot be determined and could be as late as the Pliocene epoch (5.3–2.6 Mya) (top left), (2) geographical isolation and genetic divergence of C. ryukyueneis in the Ryukyu Arc from mainland Asian mandarins during early Pleistocene (top right), (3) divergence of mangshanyeju and common mandarins (bottom left), and (4) current distribution of east Asian citrus with C. ryukyuensis ancestry in the Ryukyu Arc and mainland Japan, as a result of distinct hybridization events with different migrant mainland mandarins (bottom right). (Maps are adapted from Kimura25 with paleo-landmasses in light green.) Source data underlying Fig. 2a are provided as a Source Data file.
