Genetic population structure and ecophysiological differentiation of Japanese flounder

点击翻译按钮获取中文摘要

Analyses on sequence of mtDNA control region were conducted for Japanese flounder collected in Hokkaido, Kochi, Mie, southern Korea and near Qingdau, China. Composition of major 2 haplotypes and Fst value analyses for all data previously published including Sado Island analyzed by Fujii and Nishida (1997) demonstrated homogeneous genetic structure in the Japanese flounder distributed around Japan although slight but significant difference was only found between Sado Island and the others. A different haplotype composition was observed in Chinese population. On the other hand, the flounder collected from southern Korea showed almost same base alignment, and they were supposed to be discarded hatchery-raised juveniles.Rearing experiments were done to see differences in eco-physiological characteristics between cold-water adapted northern population and warm-adapted southern population. Fertilized flounder eggs were transported from Miyako, Iwate and from Amakusa, Kumamoto to the Fisheries Station of Kyoto University, and the larvae were reared from hatching through completion of metamorphosis at water temperatures 14, 18, and 22℃ using closed circulating aquaria. Early juveniles reared at 18℃ were transferred to 6 temperature regimes 10, 14, 18, 22, 26, 30℃ and reared until 50mm SL. These rearing experiments suggested that northern population has higher growth potential than southern population under lower temperatures.Based on these data we could conclude that Japanese flounder local population has different physiological characteristics adapted to regional environments even when they demonstrate a homogeneous genetic structure.