Divergence and Long-Distance Overseas Dispersals of Island Populations of the Ryukyu Five-Lined Skink, Plestiodon Marginatus (Scincidae: Squamata), in the Ryukyu Archipelago, Japan, as Revealed by Mitochondrial DNA Phylogeography

Abstract

We assessed the historical biogeography of the Ryukyu five-lined skink, Plestiodon marginatus, and related species (P. stimpsonii and P. elegans). Our specific aims were to reveal the origin, tim- ing, and route of the colonization to three volcanic islands in the northern Tokara Group of the northern Ryukyus: Kuchinoshima, Nakanoshima, and Suwanosejima. We conducted phylogenetic analyses and divergence time estimation using a partial sequence of the mitochondrial cytochrome b gene for P. marginatus collected from across its whole range (the northern and central Ryukyus), and for P. stimpsonii (from the Yaeyama Group of the southern Ryukyus) and P. elegans (from Taiwan). Our results suggest three major clades (A, B, and C). Clades A and B consist of P. marginatus, excluding the Kuchinoshima population, and Clade C consisted of the Kuchinoshima population, P. stimpsonii, and P. elegans. These clades are estimated to have diverged during the Late Miocene to the Late Pliocene. Among the three examined northern Tokara populations, the Kuchinoshima population was shown to be a sister group of P. stimpsonii. The two other populations from Nakanoshima and Suwanosejima Islands were closely related to P. marginatus from the northern part of the Okinawa Group and that from Kodakarajima Island in the southern Tokara Group, respectively. These populations are estimated to have diverged from their respective related spe cies in various ages of the Early to Late Pleistocene, suggesting that they colonized the islands by independent overseas dispersals of approximately 50-850 km via the Kuroshio Current. Taxonomic implications for P. marginatus are also discussed.

The evolutionary history and taxonomic reevaluation of the Japanese coral snake,Sinomicrurus japonicus(Serpentes, Elapidae), endemic to the Ryukyu Archipelago, Japan, by use of molecular and morphological analyses

“…Similarly, divergence of the Kumejima population from populations of Okinawajima and adjacent islets is also estimated to have taken place in the same period (Node D in Fig. ), being well compatible to those for a few other taxa examined so far (scincid lizards, Kurita and Hikida ; natricine snakes, Kaito and Toda ). The divergences in this location are also considered to have resulted from vicariance by the same geohistorical movements.…”

“…; crocodile newts, Honda et al. ; five‐lined skinks, Kurita and Hikida ), and the Japanese coral snake is also well concordant with this estimation (Node C in Fig. , Table ).…”

Fine‐scale demographic processes resulting from multiple overseas colonization events of the Japanese stream tree frog, Buergeria japonica

“…Several researchers suggested that the Kuroshio Current, a major ocean current that flows north‐eastward from Taiwan, has been a major factor influencing overseas dispersal of organisms from southern to northern islands (Kurita & Hikida, ). The current is thought to have driven long‐distance dispersals of small terrestrial animals over thousands of kilometres.…”

Complex inter‐island colonization and peripatric founder speciation promote diversification of flightless Pachyrhynchus weevils in the Taiwan–Luzon volcanic belt

“…This northward "stepping-stone by island distance" model of colonization may have been facilitated by the regionally dominant surface Kuroshio current, which originates at the equator and flows northerly towards the Philippines, Taiwan-Luzon volcanic belt and Japanese islands. The Kuroshio current is thought to be a strong oceanic mechanism in shaping the distribution of tropical sea grasses (Kuo, Kanamoto, Iizumi, Aioi, & Mukai, 2006) and population genetic structures of skinks in the Ryukyu Archipelago (Kurita & Hikida, 2014). However, the stepping-stone model of colonization in the Taiwan-Luzon volcanic belt has never been rigorously tested using a molecular phylogeographical approach, with the exception of some phylogenetic studies of shrews (Esselstyn & Oliveros, 2010), birds (Oliveros & Moyle, 2010) and geckos (Siler, Oaks, Cobb, Ota, & Brown, 2014), which indicated a direction of colonization from either Northern Taiwan (shrews) and Batanes (birds) or Southern Luzon (geckos).…”