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ID 33948
file
creator
Nishitani, Takuma
Katsuren, Seiki
Oumi, Shohei
subject
crocodile newts
divergence age
endangered species
mitochondrial genome
Ryukyu Islands
NDC
Zoology
abstract
Crocodile newts, which constitute the genera Echinotriton and Tylototriton, are known as living fossils, and these genera comprise many endangered species. To identify mitochondrial (mt) genes suitable for future population genetic analyses for endangered taxa, we determined the complete nucleotide sequences of the mt genomes of the Japanese crocodile newt Echinotriton andersoni and Himalayan crocodile newt Tylototriton verrucosus. Although the control region (CR) is known as the most variable mtDNA region in many animal taxa, the CRs of crocodile newts are highly conservative. Rather, the genes of NADH dehydrogenase subunits and ATPase subunit 6 were found to have high sequence divergences and to be usable for population genetics studies. To estimate the inter-population divergence ages of E. andersoni endemic to the Ryukyu Islands, we performed molecular dating analysis using whole and partial mt genomic data. The estimated divergence ages of the inter-island individuals are older than the paleogeographic segmentation ages of the islands, suggesting that the lineage splits of E. andersoni populations were not caused by vicariant events. Our phylogenetic analysis with partial mt sequence data also suggests the existence of at least two more undescribed species in the genus Tylototriton. We also found unusual repeat sequences containing the 3′ region of cytochrome apoenzyme b gene, whole tRNA-Thr gene, and a noncoding region (the T-P noncoding region characteristic in caudate mtDNAs) from T. verrucosus mtDNA. Similar repeat sequences were found in two other Tylototriton species. The Tylototriton taxa with the repeats become a monophyletic group, indicating a single origin of the repeat sequences. The intra-and inter-specific comparisons of the repeat sequences suggest the occurrences of homologous recombination-based concerted evolution among the repeat sequences.
journal title
Genes & Genetic Systems
volume
Volume 87
issue
Issue 1
start page
39
end page
51
date of issued
2012
publisher
日本遺伝学会
issn
1341-7568
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 2012 by The Genetics Society of Japan
relation url
department
Graduate School of Science