Colour variation in marine invertebrates is typically attributed to intraspecific variability; however, the use of molecular tools to investigate its genetic basis has uncovered many instances of cryptic speciation. The colonial ascidian Distaplia bermudensis occurs in a wide array of colour morphs, ranging from all white to a dark blue tunic with yellow siphon apertures; yet careful observations of zooid and larval morphologies have not revealed any consistent difference among these colour morphs. In this study, we sampled the 5 main colour morph groupings of D. bermudensis from Wilmington, North Carolina (USA) and sequenced fragments of the mitochondrial cytochrome c oxidase subunit I (COI) and the nuclear 18S rRNA genes. Analyses of both genes revealed the presence of two distinct genetic lineages that corresponded to unique colour morphology groupings. We further characterized symbiotic microbial communities for four samples from each lineage by high-throughput sequencing of partial 16S rRNA genes. Each genetic lineage also harboured unique symbiont communities that differed significantly in diversity and structure. Thus, the two genetic lineages detected herein corresponded to unique colour morphs and microbial communities, indicating that two distinct species coexist under the same scientific name. Further, our study reports the utility of symbiont profiling in resolving the taxonomic status of phenotypically variable ascidian species.

中文翻译：

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殖民地海鞘的隐秘遗传谱系宿主不同的微生物组

海洋无脊椎动物的颜色变化通常归因于种内变异；然而，使用分子工具来研究其遗传基础已经发现了许多神秘物种形成的例子。殖民地海鞘Distaplia bermudensis有多种颜色形态，从全白到带有黄色虹吸孔的深蓝色外衣；然而，对动物和幼虫形态的仔细观察并未揭示这些颜色形态之间存在任何一致的差异。在这项研究中，我们对D. bermudensis的 5 个主要颜色形态分组进行了采样来自北卡罗来纳州威尔明顿（美国）并对线粒体细胞色素 c 氧化酶亚基 I (COI) 和核 18S rRNA 基因的片段进行测序。对这两个基因的分析揭示了两个不同的遗传谱系的存在，它们对应于独特的颜色形态分组。我们通过部分 16S rRNA 基因的高通量测序进一步表征了来自每个谱系的四个样本的共生微生物群落。每个遗传谱系还包含独特的共生群落，它们在多样性和结构上存在显着差异。因此，这里检测到的两个遗传谱系对应于独特的颜色形态和微生物群落，表明两个不同的物种以相同的科学名称共存。更多，