Tuesday, July 16, 2019

[Herpetology • 2019] Relict Distribution of Microhyla (Amphibia: Microhylidae) in the Ryukyu Archipelago: High Diversity in East Asia maintained by Insularization

 Microhyla okinavensis 
in Tominaga, Matsui, Shimoji, Khonsue, et al., 2019. 

The Ryukyu Archipelago, located at the southwestern part of Japan, is known as a group of continental islands and harbours many endemic taxa, supposedly reflecting its fairly long isolation from the Eurasian continent, Taiwan and the Japanese main islands. Microhyla okinavensis has been known as an endemic member of the terrestrial fauna of this archipelago. Molecular phylogenetic analyses using samples from nearly all island populations of the species and representative samples of other east Asian congeneric species revealed that M. okinavensis consists of four distinct subclades, of which the Amami, Okinawa and Miyako subclades, though exhibiting distinct genetic differentiations from each other, formed a monophyletic group (clade A). The remaining Yaeyama subclade was exclusively sister to M. mixtura from inland China, forming another monophyletic group (clade B), rendering M. okinavensis in the current definition paraphyletic. These results, as well as estimated dates of divergence from related taxa, indicate that M. okinavensis actually includes more than one distinct species. The results indicate that M. okinavensis and M. mixtura are relict species with disjunct distributions which had been most probably caused by invasion of M. fissipes in intervening areas.

Keywords: Continental Island, East Asia, Microhyla, phylogeography, relict lineage

Figure 2: Maximum likelihood phylogenetic tree of total 826 bp of the mitochondrial genes (12S and 16SrRNA) for 75 samples of Microhyla and additional five M. beilunensis.

Atsushi Tominaga, Masafumi Matsui, Naoko Shimoji, Wichase Khonsue, Chi‐Shiun Wu, Mamoru Toda, Koshiro Eto, Kanto Nishikawa and Hidetoshi Ota. 2019. Relict Distribution of Microhyla (Amphibia: Microhylidae) in the Ryukyu Archipelago: High Diversity in East Asia maintained by Insularization. Zoologica Scripta. 48(4); 440-453.  DOI: 10.1111/zsc.12361 


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