Sudasinghe Hiranya, Ranasinghe Tharindu, Wijesooriya Kumudu, Rüber Lukas, Meegaskumbura Madhava
Evolutionary Ecology and Systematics Laboratory, Department of Molecular Biology and Biotechnology, University of Peradeniya, Peradeniya, Sri Lanka.
Postgraduate Institute of Science, University of Peradeniya, Peradeniya, Sri Lanka.
J Fish Biol. 2024 Jul;105(1):340-357. doi: 10.1111/jfb.15792. Epub 2024 May 20.
Three nominal species of the killifish genus Aplocheilus are reported from the lowlands of Sri Lanka. Two of these, Aplocheilus dayi and Aplocheilus werneri, are considered endemic to the island, whereas Aplocheilus parvus is reported from both Sri Lanka and Peninsular India. Here, based on a collection from 28 locations in Sri Lanka, also including a dataset of Asian Aplocheilus downloaded from GenBank, we present a phylogeny constructed from the mitochondrial cytochrome b (cytb), mitochondrial cytochrome c oxidase subunit 1 (cox1), and nuclear recombination activating protein 1 (rag1), and investigate the interrelationships of the species of Aplocheilus in Sri Lanka. The endemic Sri Lankan aplocheilid clade comprising A. dayi and A. werneri is recovered as the sister group to the clade comprising A. parvus from Sri Lanka and Aplocheilus blockii from Peninsular India. The reciprocal monophyly of A. dayi and A. werneri is not supported in our molecular phylogeny. A. dayi and A. werneri display strong sexual dimorphism, but species-level differences are subtle, explained mostly by pigmentation patterns. Their phenotypes exhibit a parapatric distribution and may represent locally adapted forms of a single species. Alternatively, the present study does not rule out the possibility that A. dayi and A. werneri may represent an incipient species pair or that they have undergone introgression or hybridization in their contact zones. We provide evidence that the Nilwala-Gin region of southwestern Sri Lanka may have acted as a drought refugium for these fishes.
据报道，斯里兰卡低地有三种名义上的鳉属鱼类。其中两种，即达氏鳉（Aplocheilus dayi）和韦氏鳉（Aplocheilus werneri）被认为是该岛特有的，而细鳉（Aplocheilus parvus）在斯里兰卡和印度半岛都有报道。在此，基于从斯里兰卡28个地点采集的样本，还包括从GenBank下载的亚洲鳉属数据集，我们构建了一个由线粒体细胞色素b（cytb）、线粒体细胞色素c氧化酶亚基1（cox1）和核重组激活蛋白1（rag1）组成的系统发育树，并研究了斯里兰卡鳉属物种之间的相互关系。包括达氏鳉和韦氏鳉在内的斯里兰卡特有鳉科分支被发现是由来自斯里兰卡的细鳉和来自印度半岛的布氏鳉组成的分支的姐妹群。在我们的分子系统发育中，达氏鳉和韦氏鳉的相互单系性没有得到支持。达氏鳉和韦氏鳉表现出强烈的两性异形，但物种水平的差异很细微，主要由色素沉着模式来解释。它们的表型呈现出邻域分布，可能代表了一个单一物种的局部适应形式。或者，本研究并不排除达氏鳉和韦氏鳉可能代表一个初始物种对，或者它们在接触区域经历了基因渗入或杂交的可能性。我们提供的证据表明，斯里兰卡西南部的尼尔瓦拉 - 金地区可能曾是这些鱼类的干旱避难所。
