Genetic population structure and ecophysiological differentiation of Japanese flounder

对采自朝鲜南部北海道、高知县、密西西比州和中国青岛市附近的日本比目鱼的线粒体DNA控制区序列进行了分析。Fujii和Nishida(1997)对包括佐渡岛在内的所有已发表数据的主要两种单倍型的组成和Fst值分析表明，分布在日本各地的牙鲆具有同质性的遗传结构，但只有佐渡岛与其他鱼类存在轻微但显着的差异。在中国人群中观察到一种不同的单倍型组成。另一方面，从韩国采集的比目鱼显示出几乎相同的碱基排列，它们应该是被丢弃的孵化饲养的幼鱼。重新实验观察了冷水适应的北方种群和温暖适应的南方种群的生态生理特征的差异。受精卵分别从岩手县宫古县和熊本市的阿马库萨运至京都大学渔业站，在水温14、18、22℃的水温下用闭式循环水族箱进行孵化和变态培育。在18℃饲养的早期幼鱼被转移到10、14、18、22、26、30℃6个温度段，饲养到50 mm SL。这些饲养实验表明，在较低的温度下，北方种群比南方种群具有更高的增长潜力。根据这些数据，我们可以得出结论，即使在遗传结构相同的情况下，南方种群也具有不同的生理特征来适应区域环境。

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.