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25 February 2021 Complex Historical Biogeography of the Eastern Japanese Skink, Plestiodon finitimus (Scincidae, Squamata), Revealed by Geographic Variation in Molecular and Morphological Characters
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Abstract

We investigated the geographic diversification of Plestiodon finitimus, which occurs in the central to northern parts of the Japanese Islands, based on a time-calibrated mitochondrial DNA (mtDNA) phylogeny and external morphological characters. The mtDNA phylogeny suggests that P. finitimus diverged from its sister species Plestiodon japonicus in western Japan 2.82–4.63 million years ago (MYA), which can be explained by geographic isolation due to the spread of sedimentary basins in the Pliocene. The primary intraspecific divergence was that between P. finitimus lineages in central and northeastern Japan 1.58–2.76 MYA, which could have been caused by the upliftings of major mountain ranges. In the northeastern lineage, mtDNA and morphological characters suggest a geographic differentiation between sub-lineages of the northwestern Tohoku District (α) and other areas (β). Although the sub-lineage β occurs in a disjunct geographic range, consisting of Hokkaido and the central to south of Tohoku, these areas are bridged by populations with intermediate characteristics along the Pacific side of northern Tohoku. Overall, the geographic variation in P. finitimus in northern Japan can be explained by an initial allopatric divergence of the sub-lineages α and β at 0.71–1.39 MYA, a recent northward expansion of the sub-lineage β, and subsequent secondary introgressive hybridization between the sub-lineages.

© 2021 Zoological Society of Japan
Taku Okamoto, Seita Tsukamoto, Masaki Kuro-o, Takeo Kuriyama, and Masaharu Motokawa "Complex Historical Biogeography of the Eastern Japanese Skink, Plestiodon finitimus (Scincidae, Squamata), Revealed by Geographic Variation in Molecular and Morphological Characters," Zoological Science 38(2), 148-161, (25 February 2021). https://doi.org/10.2108/zs200051
Received: 10 April 2020; Accepted: 24 November 2020; Published: 25 February 2021
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