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Vicariant speciation due to 1.55 Ma isolation of the R yukyu islands, J apan, based on geological and G en B ank data
Author(s) -
Osozawa Soichi,
Su ZhiHui,
Oba Yuichi,
Yagi Takashi,
Watanabe Yasushi,
Wakabayashi John
Publication year - 2013
Publication title -
entomological science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 28
eISSN - 1479-8298
pISSN - 1343-8786
DOI - 10.1111/ens.12037
Subject(s) - vicariance , biology , rift , phylogenetic tree , botany , trough (economics) , paleontology , phylogeography , tectonics , genetics , macroeconomics , economics , gene
The R yukyu island arc, originally a continental margin arc, separated from the C hinese continent by the rifting of the O kinawa trough, a process which began at 1.55 million years ago ( M a) and continues to the present. In addition, the R yukyu arc was simultaneously divided into the northern A mami– O kinawa and southern Y aeyama islands by the K erama rift valley, and consequently formed two isolated island units. The K uroshio warm current began to flow into the O kinawa trough from the Y onaguni S trait, and flow out through the T sushima and T okara straits also at 1.55 Ma, and these seaways effectively acted as barriers between the R yukyu islands and T aiwan, C hina and J apan. Through this geological process, vicariant speciation generated R yukyu endemic animal species. We support this hypothesis by drawing linearized maximum likelihood ( ML ) phylogenetic trees of the species in four endemic insect groups (peacock butterfly, C hinese windmill butterfly, golden‐ringed dragonfly, window firefly) using G en B ank sequence data. We determined the precise branching ages for these phylogenetic trees, and show simultaneous speciation at 1.55 Ma for A mami– O kinawa and Y aeyama units. The T aiwan and T sushima straits, barriers between T aiwan and C hina, and J apan and K orea, respectively, did not form sufficient barriers to migration during glacial low stands, and species were intermingled. A marine embayment may have posed as a migration barrier between northern and southern C hina in the Q uaternary or a little earlier. From our study we also estimate the precise molecular evolution rate and justify the molecular clock.