Mokodongan Daniel F, Montenegro Javier, Mochida Koji, Fujimoto Shingo, Ishikawa Asano, Kakioka Ryo, Yong Lengxob, Hadiaty Renny K, Mandagi Ixchel F, Masengi Kawilarang W A, Wachi Nakatada, Hashiguchi Yasuyuki, Kitano Jun, Yamahira Kazunori
Tropical Biosphere Research Center, University of the Ryukyus, Okinawa 903-0213, Japan.
Tropical Biosphere Research Center, University of the Ryukyus, Okinawa 903-0213, Japan; Department of Biology, Keio University, Kanagawa 223-8521, Japan.
Mol Phylogenet Evol. 2018 Jan;118:194-203. doi: 10.1016/j.ympev.2017.10.005. Epub 2017 Oct 9.
The Oryzias woworae species group, composed of O. asinua, O. wolasi, and O. woworae, is widely distributed in southeastern Sulawesi, an island in the Indo-Australian Archipelago. Deep-elongated body shape divergence is evident among these three species to the extent that it is used as a species-diagnostic character. These fishes inhabit a variety of habitats, ranging from upper streams to ponds, suggesting that the body shape divergence among the three species may reflect adaptation to local environments. First, our geometric morphometrics among eight local populations of this species group revealed that the three species cannot be separated by body shape and that riverine populations had more elongated bodies and longer caudal parts than lacustrine populations. Second, their phylogenetic relationships did not support the presence of three species; phylogenies using mitochondrial DNA and genomic data obtained from RNA-Seq revealed that the eight populations could not be sorted into three different clades representing three described species. Third, phylogenetic corrections of body shape variations and ancestral state reconstruction of body shapes demonstrated that body shape divergence between riverine and lacustrine populations persisted even if the phylogenies were considered and that body shape evolved rapidly irrespective of phylogeny. Sexual dimorphism in body shape was also evident, but the degree of dimorphism did not significantly differ between riverine and lacustrine populations after phylogenetic corrections, suggesting that sexual selection may not substantially contribute to geographical variations in body shape. Overall, these results indicate that the deep-elongated body shape divergence of the O. woworae species group evolved locally in response to habitat environments, such as water currents, and that a thorough taxonomic reexamination of the O. woworae species group may be necessary.
由阿氏稻田鱼、沃氏稻田鱼和沃氏稻眼鱼组成的沃氏稻眼鱼物种组广泛分布于印度-澳大利亚群岛中的苏拉威西岛东南部。这三个物种之间身体形状深度拉长的差异很明显，以至于被用作物种诊断特征。这些鱼类栖息于从上游溪流到池塘的各种栖息地，这表明这三个物种之间的身体形状差异可能反映了对当地环境的适应。首先，我们对该物种组的八个本地种群进行的几何形态测量显示，这三个物种无法通过身体形状区分，并且河流种群的身体比湖泊种群的更长，尾部也更长。其次，它们的系统发育关系并不支持存在三个物种；使用线粒体DNA和从RNA测序获得的基因组数据构建的系统发育树表明，这八个种群无法被分类为代表三个已描述物种的三个不同分支。第三，对身体形状变化的系统发育校正和身体形状的祖先状态重建表明，即使考虑系统发育，河流和湖泊种群之间的身体形状差异仍然存在，并且身体形状的进化与系统发育无关，速度很快。身体形状的两性异形也很明显，但经过系统发育校正后，河流和湖泊种群之间的两性异形程度没有显著差异，这表明性选择可能对身体形状的地理变异没有实质性贡献。总体而言，这些结果表明，沃氏稻眼鱼物种组深度拉长的身体形状差异是为响应水流等栖息地环境而在当地进化形成的，并且可能有必要对沃氏稻眼鱼物种组进行全面的分类学重新审视。
