In this study, we analyzed nuclear DNA (nDNA) variation by means of genotyping-by-sequencing (GBS) of three disc-bearing and seven non-disc-bearing Garra tashanensis from the Tashan Cave in Iran to clarify their systematic and ecological relationships. We performed genetic differentiation, NeighborNet, Admixture, and principal component analyses on genomic data. Admixture and principal component analyses revealed clear genetic differentiation between disc-bearing and non-disc-bearing morphotypes, which was not detected by mtDNA markers in previous work. However, there was a non-disc-bearing individual that clustered with disc-bearing individuals. Based on the results of this study, the most parsimonious justification for coexistence of disc-bearing and non-disc-bearing forms of Garra in Tashan Cave is a combination of mechanisms similar to character release (intra-specific morphological diversification to exploit a wider range of habitats in the absence of competitors or predators) and relaxed selection (no more selective advantage for a previously advantageous trait as a result of ecological changes). The detected genetic structure may be an indication of reproductive isolation between the two groups. These data imply that the respective forms of the Tashan Cave barb could be a case of ongoing sympatric speciation, but also that disc form cannot be used as a taxonomic character for Tashan Cave barb forms.

在本研究中，我们通过测序基因分型 (GBS) 分析了来自伊朗塔山洞穴的 3 种有盘和 7 种无盘的 Garra tashanensis 的核 DNA (nDNA) 变异，以阐明它们的系统和生态关系。我们对基因组数据进行了遗传分化、NeighborNet、混合和主成分分析。混合物和主成分分析揭示了带盘和不带盘的形态类型之间存在明显的遗传分化，这是以前的工作中 mtDNA 标记未检测到的。然而，有一个不带有椎间盘的个体与带有椎间盘的个体聚集在一起。根据这项研究的结果，塔山洞穴中盘状和非盘状的Garra共存的最简单的理由是类似于特征释放的机制的组合（种内形态多样化，以开发更广泛的范围）在没有竞争者或捕食者的情况下栖息地）和宽松的选择（由于生态变化而不再对先前有利的性状产生选择性优势）。检测到的遗传结构可能表明两个群体之间存在生殖隔离。这些数据表明，塔山洞倒刺的各自形态可能是持续同域物种形成的一个例子，但盘状形态不能用作塔山洞倒刺形态的分类特征。