Kusaka et al.: Genetic population structure of Dipturus chinensis around Japan 
109 
Acknowledgments 
We thank H. Kanehara, T. Aoshima, G. Kume, and the staffs 
of the training ships Nagasaki-Maru (Nagasaki Univer- 
sity) and Kagoshima-Maru (Kagoshima University), the 
staffs of the RV Mizuho-Maru (Japan Sea National Fish- 
eries Research Institute) and the RV Heian-Maru (Kyoto 
Institute of Oceanic and Fishery Science), and trawl fish- 
ermen of the FV Kosei-Maru (Mimase, Kochi Prefecture) 
and FV Kyuei-Maru (Hachinohe, Aomori Prefecture) for 
collecting samples. This work was supported in part by the 
Japan Fisheries Agency. 
Literature cited 
Akihito, A. Fumihito, Y. Ikeda, M. Aizawa, T. Makino, Y. Umehara, 
Y. Kai, Y. Nishimoto, M. Hasegawa, T. Nakabo, et al. 
2008. Evolution of Pacific Ocean and the Sea of Japan popula- 
tions of the gobiid species, Pterogobius elapoides and Ptero- 
gobius zonoleucus, based on molecular and morphological 
analyses. Gene 427:7-18. 
Bouckaert, R., J. Heled, D. Kiihnert, T. Vaughan, C.-H. Wu, D. Xie, 
M. A. Suchard, A. Rambaut, and A. J. Drummond. 
2014. BEAST 2: a software platform for Bayesian evolution- 
ary analysis. PLoS Comput. Biol. 10(4):e1003537. 
Brander, K. 
1981. Disappearance of common skate Raja batis from Irish 
Sea. Nature 290:48—49. 
Chevolot, M., J. R. Ellis, G. Hoarau, A. D. Rijnsdorp, W. T. Stam, 
and J. L. Olsen. 
2006a. Population structure of the thornback ray (Raja clav- 
ata L.) in British waters. J. Sea Res. 56:305-316. 
Chevolot, M., G. Hoarau, A. D. Rijnsdorp, W. T. Stam, and 
J. L. Olsen. 
2006b. Phylogeography and population structure of thornback 
rays (Raja clavata L., Rajidae). Mol. Ecol. 15:3693-3705. 
Chevolot, M., P. H. J. Wolfs, J. Palsson, A. D. Rijnsdorp, W. T. Stam, 
and J. L. Olsen. 
2007. Population structure and historical demography of the 
thorny skate (Amblyraja radiata, Rajidae) in the North 
Atlantic. Mar. Biol. 151:1275-1286. 
Clement, M., D. Posada, and K. A. Crandall. 
2000. TCS: a computer program to estimate gene genealogies. 
Mol. Ecol. 9:1657—-1659. 
Domingues, R. R. D., A. W. S. Hilsdorf, and O. B. F. Gadig. 
2018. The importance of considering genetic diversity in shark 
and ray conservation policies. Conserv. Genet. 19:501—525. 
Drummond, A. J., A. Rambaut, B. Shapiro, and O. G. Pybus. 
2005. Bayesian coalescent inference of past population 
dynamics from molecular sequences. Mol. Biol. Evol. 
22:1185-1192. 
Dulvy, N. K., J. D. Metcalfe, J. Glanville, M. G. Pawson, and 
J. D. Reynolds. 
2000. Fishery stability, local extinctions, and shifts in com- 
munity structure in skates. Conserv. Biol. 14:283-293. 
El Nagar, A., M. McHugh, T. Rapp, D. W. Sims, and M. J. Genner. 
2010. Characterisation of polymorphic microsatellite mark- 
ers for skates (Elasmobranchii: Rajidae) from expressed 
sequence tags. Conserv. Genet. 11:1203-1206. 
Excoffier, L., and H. E. L. Lischer. 
2010. Arlequin suite ver 3.5: a new series of programs to per- 
form population genetics analyses under Linux and Win- 
dows. Mol. Ecol. Resour. 10:564—567. 
Excoffier, L., P. E. Smouse, and J. M. Quattro. 
1992. Analysis of molecular variance inferred from metric 
distances among DNA haplotypes: application to human 
mitochondrial DNA restriction data. Genetics 131:479—491. 
Felsenstein, J. 
1985. Confidence limits on phylogenies: an approach using 
bootstrap. Evolution 39:783-791. 
Ferrari, A., F. Tinti, V. B. Maresca, A. Velona, R. Cannas, I. Thasitis, 
F. O. Costa, M. C. Follesa, D. Golani, F. Hemida, et al. 
2018. Natural history and molecular evolution of demersal 
Mediterranean sharks and skates inferred by comparative 
phylogeographic and demographic analyses. PeerJ 6:e5560. 
Frodella, N., R. Cannas, A. Vilona, P. Carbonara, E. D. Farrell, 
F. Fiorentino, M. C. Follesa, G. Garofalo, F. Hemida, C. Mancusi, 
et al. 
2016. Population connectivity and pylogeography of the Med- 
iterranean endemic skate Raja polystigma and evidence of 
its hybridization with the parapatric sibling R. montagut. 
Mar. Ecol. Prog. Ser. 554:99-113. 
Fu, Y.-X. 
1997. Statistical tests of neutrality of mutations against 
population growth, hitchhiking and background selection. 
Genetics 147:915-925. 
Gallagher, S. J., A. Kitamura, Y. Iryu, T. Itaki, I. Koizumi, and 
P. W. Hoiles. 
2015. The Pliocene to recent history of the Kuroshio and 
Tsushima currents: a multi-proxy approach. Prog. Earth 
Planet. Sci. 2:17. 
Goudet, J. 
2002. FSTAT: a program to estimate and test gene diversities 
and fixation indices, vers. 2.9.3.2. [Available from website, 
accessed September 2018.] 
Grant, W. A. S., and B. W. Bowen. 
1998. Shallow population histories in deep evolutionary lin- 
eages of marine fishes: insights from sardines and ancho- 
vies and lessons for conservation. J. Hered. 89:415—426. 
Griffiths, A. M., D. W. Sims, S. P. Cotterell, A. El] Nagar, J. R. Ellis, 
A. Lynghammar, M. McHugh, F. C. Neat, N. G. Pade, N. Queiroz, 
et al. 
2010. Molecular markers reveal spatially segregated cryp- 
tic species in a critically endangered fish, the common 
skate (Dipturus batis). Proc. R. Soc., B 277:1497-1503. 
Griffiths, A. M., D. W. Sims, A. Johnson, A. Lynghammar, 
M. McHugh, T. Bakken, and M. J. Genner. 
2011. Levels of connectivity between longnose skate (Dip- 
turus oxyrinchus) in the Mediterranean Sea and the north- 
eastern Atlantic Ocean. Conserv. Genet. 12:577-582. 
GSI (Geographical Survey Institute). 
1990. The national atlas of Japan, rev. ed., 219 p. GSI, Tokyo, 
Japan. [Available from website.] 
Guo, S. W., and E. A. Thompson. 
1992. Performing the exact test for Hardy—Weinberg propor- 
tion for multiple alleles. Biometrics 48:361—372. 
Han, Z., T. Yanagimoto, Y. Zhang, and T. Gao. 
2012. Phylogeography study of Ammodytes personatus in 
northwestern Pacific: Pleistocene isolation, temperature 
and current conducted secondary contact. PLoS ONE 
7(5):e37425. 
Hara, K., K. Furumitsu, and A. Yamaguchi. 
2014. Record of a Korean skate, Hongeo koreana (Jeong and 
Nakabo, 1997) from off Goto islands. Rep. Jap. Soc. Elasmo- 
branch Stud. 50:21—26. [In Japanese.] 
Hara, K., K. Furumitsu, T. Aoshima, H. Kanehara, and 
A. Yamaguchi. 
2018a. Age, growth, and age at sexual maturity of the 
commercially landed skate species, Dipturus chinensis 
