Gómez-Buckley Marta C, Pedraza-Marrón Carmen Del R, Erdmann Mark V, Tornabene Luke M
School of Aquatic and Fishery Sciences and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA.
Department of Life and Environmental Sciences, University of California, Merced, CA, USA.
Mol Phylogenet Evol. 2025 Jul 28;213:108426. doi: 10.1016/j.ympev.2025.108426.
Cryptobenthic reef fishes (CRF), although the smallest vertebrates on coral reefs, account for approximately 40% of fish species and nearly 50% of fish abundance within these ecosystems. Their diversity can be attributed to their extremely limited dispersal abilities and short generation times, which promote allopatric speciation, along with their ability to partition microhabitats at a very fine scale. Notably, the small size, cryptic nature, and conserved morphology of some CRF groups have contributed to the presence of many undetected cryptic species, which may require a genome-wide species delimitation approach to discern how many species are present. In particular, the genus Eviota is one of the most species-rich groups, with 133 species described to date. It ranges from the Red Sea to Hawaii and French Polynesia and is known to comprise numerous cryptic species. Here, we conducted an integrative species delimitation study of the Eviota sigillata species complex, which includes two nominal species described based on morphological characters; however preliminary genetic data suggest the presence of multiple cryptic lineages. We used molecular data from mitochondrial DNA and genome-wide SNP data generated via double digest restriction site associated sequencing (ddRADseq), in combination with morphological data to infer the number of species in the E. sigillata species complex. Specifically, we estimated phylogenetic trees, conducted several types of single-locus and multilocus species delimitation analyses, and compared these to groupings based on morphology and geographic distribution. Collectively we found evidence for the presence of 9-13 lineages within the E. sigillata species complex, with genetic lineages corresponding well with the biogeographic history of the group. Our results support the existence of at least nine species. We further confirmed that the original morphological diagnostic characters used for the taxonomic identification of the two nominal species were not useful for distinguishing each of the nine clades in the complex, but may be helpful in diagnosing groups of closely-related species. Overall, our study sheds light onto the patterns of speciation within CRF and provides a glimpse of the tremendous hidden diversity that still remains to be discovered in coral reef fishes.
隐栖性礁栖鱼类（CRF）虽然是珊瑚礁上最小的脊椎动物，但却占这些生态系统中鱼类物种的约40%以及鱼类数量的近50%。它们的多样性可归因于其极其有限的扩散能力和较短的世代时间，这促进了异域物种形成，以及它们在非常精细的尺度上划分微生境的能力。值得注意的是，一些CRF类群的小体型、隐匿特性和保守形态导致存在许多未被发现的隐存物种，这可能需要采用全基因组物种界定方法来辨别存在多少物种。特别是，埃氏鳚属（Eviota）是物种最丰富的类群之一，迄今已描述了133个物种。它分布于从红海到夏威夷和法属波利尼西亚的区域，已知包含众多隐存物种。在此，我们对西格氏埃氏鳚（Eviota sigillata）物种复合体进行了综合物种界定研究，该复合体包括基于形态特征描述的两个指名物种；然而初步的遗传数据表明存在多个隐存谱系。我们使用了来自线粒体DNA的分子数据以及通过双酶切限制性位点关联测序（ddRADseq）生成的全基因组SNP数据，并结合形态数据来推断西格氏埃氏鳚物种复合体中的物种数量。具体而言，我们估计了系统发育树，进行了几种类型的单基因座和多基因座物种界定分析，并将这些结果与基于形态和地理分布的分组进行比较。总体而言，我们发现有证据表明西格氏埃氏鳚物种复合体中存在9 - 13个谱系，遗传谱系与该类群的生物地理历史高度吻合。我们的结果支持至少存在九个物种。我们进一步证实，用于这两个指名物种分类鉴定的原始形态诊断特征对于区分该复合体中的九个分支并无用处，但可能有助于诊断密切相关的物种组。总体而言，我们的研究揭示了CRF内的物种形成模式，并让我们初步了解了珊瑚礁鱼类中仍有待发现的巨大隐藏多样性。
