Tropical Biosphere Research Center, University of the Ryukyus, Okinawa 903-0213, Japan; Museum Zoologicum Bogoriense, Research Center for Biology, National Research and Innovation Agency, Cibinong 16911, Indonesia.
Faculty of Fisheries and Marine Science, Sam Ratulangi University, Manado 95115, Indonesia.
Mol Phylogenet Evol. 2022 Aug;173:107519. doi: 10.1016/j.ympev.2022.107519. Epub 2022 May 13.
Sulawesi is a biodiversity hotspot for ricefishes (Adrianichthyidae), with many species endemic to the central part of this island in single ancient lakes or lake systems. Frequent vicariance by lake fragmentation since the Pliocene may be largely responsible for diversification in this family. In this study, we demonstrate that not only lacustrine species but also riverine species in this area are also deeply divergent even within a single river system. A mitochondrial phylogeny revealed that a ricefish population newly discovered from Cerekang River is sister to Oryzias dopingdopingensis Mandagi, Mokodongan, Tanaka, & Yamahira, another riverine species endemic to Doping-doping River. However, the Cerekang Oryzias was genetically isolated from O. dopingdopingensis, despite that Cerekang River and Doping-doping River share a connection across estuarine waters. This separation was supported by phylogenomic trees and population genetic structure analyses based on genome-wide single nucleotide polymorphisms. Coalescent-based demographic inference demonstrated that the ancestral population of these two riverine ricefishes had experienced a substantial population decrease and subsequently diverged into two sub-populations. Because the Cerekang Oryzias was also morphologically distinguished from O. dopingdopingensis, we described it as a new species, O. landangiensis. We infer that O. landangiensis and O. dopingdopingensis are of lake-origin and are relic species which were left in these rivers after the lake disappeared, and that they have lost their dispersal ability when inhabiting the ancient lake. The lost dispersal ability possibly contributed to the formation of the biodiversity hotspot for this fish group on this island.
苏拉威西岛是稻鱼（ Adrianichthyidae ）的生物多样性热点地区，该地区有许多物种是该岛中部的特有种，分布在单一的古老湖泊或湖泊系统中。上新世以来由于湖泊断裂而频繁发生的隔离可能是该科物种多样化的主要原因。在这项研究中，我们证明不仅该地区的湖泊物种，而且还有河流物种，甚至在单一的河流系统中也存在很深的分歧。线粒体系统发育树表明，从 Cerekang 河新发现的稻鱼种群与另一种分布在 Dop-ing-doping 河的特有河流物种 Oryzias dopingdopingensis Mandagi、Mokodongan、Tanaka 和 Yamahira 为姐妹关系。然而，尽管 Cerekang 河和 Dop-ing-doping 河通过河口水域相连，但 Cerekang 河的 Oryzias 与 O. dopingdopingensis 在遗传上是隔离的。系统发育树和基于全基因组单核苷酸多态性的种群遗传结构分析支持了这种分离。基于合并的种群动态推断表明，这两个河流稻鱼的祖先种群经历了大量的种群减少，随后分化成两个亚种群。由于 Cerekang 稻鱼在形态上也与 O. dopingdopingensis 有所区别，我们将其描述为一个新物种，O. landangiensis。我们推断 O. landangiensis 和 O. dopingdopingensis 是湖泊起源的，是湖泊消失后留在这些河流中的遗留物种，并且在栖息于古老湖泊时失去了扩散能力。这种失去的扩散能力可能促成了该岛这个鱼类群体的生物多样性热点的形成。
