Study on phylogeography and species taxonomy of Ateuchosaurus pellopleurus (Reptilia, Squamata, Scincidae)

概要

The Ryukyu Archipelago is an island chain located between the Japanese main islands
and Taiwan. Its northern, central and southern parts geographically delimited by two sea
straits, Tokara and Kerama Gaps, are also called as the Northern, Central, and Southern
Ryukyus. The high biodiversity in this archipelago has attracted the interests of taxonomists
and biogeographers. Especially, the reptile fauna of the Central Ryukyus shows high
endemicity, and the major endemics have the late Miocene origin. Many of the endemic
reptiles are also known to show the large genetic divergences between the Amami and
Okinawa Groups, which sometimes make demands of taxonomic revision. On the other hand,
some native reptiles and amphibians have the exceptionally wide distributions including the
Northern and Southern Ryukyus and shows continuous or complex geographic pattern of
genetic variation.
Ateuchosaurus pellopleurus (Hallowell, 1861) is a scincid lizard distributed in the
Northern and Central Ryukyus. This species has been treated as one of the Central Ryukyu
endemics because the congener does not occur the adjacent region including the Southern
Ryukyus and Taiwan. However, A. pellopleurus is distributed in the both sides of Tokara Gap.
This distribution pattern of A. pellopleurus questions the biogeographic status of this species.
In addition, A. pellopleurus has been generally considered as a single species since its original
description whereas the geographic variation data has not been investigated using genetic data
ever. Thus, the taxonomy of this species should also be assessed by molecular information.
In this study, the biogeographic status, geographic variation pattern and taxonomy of A.
pellopleurus was assessed based on molecular and morphological investigations.
MATERIALS AND METHODS
The A. pellopleurus specimens were collected to cover its whole distribution. These
specimens were morphologically observed using a stereoscopic binocular microscope. The
divergence time among A. pellopleurus and the congener was estimated using several
outgroups and DNA sequences of seven nuclear loci. The phylogenetic relationship and
population genetic characteristics were assessed using DNA sequences of mitochondrial DNA
(mtDNA) and one nuclear locus (RAG1). In addition, the detailed geographic variation in
Okinawa Group was investigated using population genetic analyses on a genome-wide SNP
dataset. ...