Department of Life Sciences, Imperial College London, Exhibition Road, London SW7 2BX, United Kingdom; Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom.
Department of Biology-Invertebrates Unit, Royal Museum for Central Africa, Joint Experimental Molecular Unit, Leuvensesteenweg 13, B-3080 Tervuren, Belgium.
Mol Phylogenet Evol. 2023 Jul;184:107759. doi: 10.1016/j.ympev.2023.107759. Epub 2023 Mar 13.
Hoverflies (Diptera: Syrphidae) are a diverse group of pollinators and a major research focus in ecology, but their phylogenetic relationships remain incompletely known. Using a genome skimming approach we generated mitochondrial genomes for 91 species, capturing a wide taxonomic diversity of the family. To reduce the required amount of input DNA and overall cost of the library construction, sequencing and assembly was conducted on mixtures of specimens, which raises the problem of chimera formation of mitogenomes. We present a novel chimera detection test based on gene tree incongruence, but identified only a single mitogenome of chimeric origin. Together with existing data for a final set of 127 taxa, phylogenetic analysis on nucleotide and amino acid sequences using Maximum Likelihood and Bayesian Inference revealed a basal split of Microdontinae from all other syrphids. The remainder consists of several deep clades assigned to the subfamily Eristalinae in the current classification, including a clade comprising the subfamily Syrphinae (plus Pipizinae). These findings call for a re-definition of subfamilies, but basal nodes had insufficient support to fully justify such action. Molecular-clock dating placed the origin of the Syrphidae crown group in the mid-Cretaceous while the Eristalinae-Syrphinae clade likely originated near the K/Pg boundary. Transformation of larval life history characters on the tree suggests that Syrphidae initially had sap feeding larvae, which diversified greatly in diet and habitat association during the Eocene and Oligocene, coinciding with the diversification of angiosperms and the evolution of various insect groups used as larval host, prey, or mimicry models. Mitogenomes proved to be a powerful phylogenetic marker for studies of Syrphidae at subfamily and tribe levels, allowing dense taxon sampling that provided insight into the great ecological diversity and rapid evolution of larval life history traits of the hoverflies.
食蚜蝇（双翅目：食蚜蝇科）是一类多样化的传粉昆虫，也是生态学的主要研究焦点，但它们的系统发育关系仍不完全清楚。我们使用基因组掠过方法为 91 个物种生成了线粒体基因组，涵盖了该科的广泛分类多样性。为了减少所需的输入 DNA量和文库构建的总体成本，我们对标本混合物进行了测序和组装，这增加了线粒体基因组嵌合体形成的问题。我们提出了一种基于基因树不一致性的新的嵌合体检测测试，但只识别出一个具有嵌合来源的线粒体基因组。结合现有数据，对最终的 127 个分类群的核苷酸和氨基酸序列进行最大似然法和贝叶斯推断的系统发育分析显示，Microdontinae 从所有其他食蚜蝇中分离出来。其余的由几个深分支组成，被归类为当前分类中的 Eristalinae 亚科，包括一个由 Syrphinae 亚科（加上 Pipizinae）组成的分支。这些发现要求对亚科进行重新定义，但基础节点的支持度不足以完全证明这种行动是合理的。分子钟测年将食蚜蝇科的冠群起源定在白垩纪中期，而 Eristalinae-Syrphinae 分支可能起源于 K/Pg 边界附近。树上幼虫生活史特征的转化表明，食蚜蝇科最初具有吸食汁液的幼虫，在始新世和渐新世期间，它们在饮食和栖息地的适应方面发生了巨大的分化，与被子植物的多样化以及各种用作幼虫宿主、猎物或拟态模型的昆虫类群的进化同时发生。线粒体基因组被证明是研究食蚜蝇科亚科和部落水平的有力系统发育标记，允许进行密集的分类群采样，深入了解食蚜蝇幼虫生活史特征的巨大生态多样性和快速进化。
