Tsugaru Strait hybrid zone between two Japanese marine sculpins (genus Cottiusculus)
Mitochondrial and nuclear DNA variations in the marine sculpin sister species Cottiusculus schmidti and C. nihonkaiensis, distributed along the Pacific coast of northern Japan and in the Sea of Japan, respectively, indicated a ca. 250-km-wide hybrid zone across the Tsugaru Strait, connecting the Pacific Ocean and Sea of Japan. In addition to incomplete postzygotic isolation between the two species, the hybrid zone may have been shaped and formed by reduced dispersal, the preferred habitat of Cottiusculus being generally deeper than Tsugaru Strait (maximum depth ca. 140 m).
KeywordsCottiusculus schmidti Cottiusculus nihonkaiensis Mitochondrial DNA Cyt-b Nuclear DNA myh6
We greatly appreciate the assistance of Y.Yagi (Japan Sea National Fisheries Research Institute), A. Yamasaki, A. Iwao, T. Miyajima and S. Noguchi and the crews of the R/V Heian-maru (Kyoto Prefectural Agriculture, Forestry and Fisheries Technology Center), K. Itoh, T. Miura and the crews of the crews of the R/V Seiho-maru (Aomori Prefectural Industrial Technology Center), and K. Sakai (Noto Marine Center, Ishikawa) in collecting specimens. We also thank G. S. Hardy (Ngunguru, New Zealand) for his critical reading of the manuscript. This study was supported in part by a grant-in-aid for scientific research (C) from JSPS (26440212).
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