Tandavanitj Nontivich, Ota Hidetoshi, Cheng Yuan-Cheng, Toda Mamoru
Graduate School of Engineering and Science, University of the Ryukyus, Nishihara, Okinawa, Japan.
Zoolog Sci. 2013 Aug;30(8):633-41. doi: 10.2108/zsj.30.633.
The Ryukyu-Taiwan region is an island arch with intervening waters of varying distances and depths. This study examines the geographic genetic structure of two sympatric sea kraits, Laticauda laticaudata and L. semifasciata, in the region, to infer factors affecting the extent of dispersal and other biogeographical traits of these amphibious reptiles. Sequence analyses of the mitochondrial cytochrome b gene revealed four and 16 haplotypes for L. laticaudata (136 individuals) and L. semifasciata (177 individuals), respectively. For both species, population pairwise F ST analyses revealed significant genetic differentiations among islands and island groups, which are separated by deep straits, suggesting that deep waters serve as obstacles for dispersal in both species. Significant genetic differentiation was detected even among islands of the same basin in L. laticaudata, but not in L. semifasciata, and the isolation by distance analyses revealed no significant correlation between geographic and genetic distances in the former species. These results further suggest that L. laticaudata has stronger site fidelity or degree of philopatry than L. semifasciata. Based on the geographic genetic patterns, the historical biogeography of the two species in the Ryukyu-Taiwan region is also discussed.
琉球 - 台湾地区是一个岛屿群岛，其间水域距离和深度各不相同。本研究考察了该地区两种同域分布的海蛇——蓝灰扁尾海蛇（Laticauda laticaudata）和半环扁尾海蛇（L. semifasciata）的地理遗传结构，以推断影响这些两栖爬行动物扩散范围及其他生物地理特征的因素。线粒体细胞色素b基因的序列分析分别揭示了蓝灰扁尾海蛇（136个个体）有4个单倍型，半环扁尾海蛇（177个个体）有16个单倍型。对于这两个物种，群体间的F ST分析表明，被深水海峡隔开的岛屿和岛屿群之间存在显著的遗传分化，这表明深水对两个物种的扩散均构成障碍。在蓝灰扁尾海蛇中，即使在同一海域的岛屿之间也检测到了显著的遗传分化，但在半环扁尾海蛇中未检测到，并且距离隔离分析表明前一个物种的地理距离和遗传距离之间没有显著相关性。这些结果进一步表明，蓝灰扁尾海蛇比半环扁尾海蛇具有更强的位点忠诚度或恋巢程度。基于地理遗传模式，还讨论了这两个物种在琉球 - 台湾地区的历史生物地理学。
