Cong Qian, Borek Dominika, Otwinowski Zbyszek, Grishin Nick V
Department of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390-8816, USA.
Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390-9050, USA.
BMC Genomics. 2015 Aug 27;16(1):639. doi: 10.1186/s12864-015-1846-0.
Butterflies and moths are emerging as model organisms in genetics and evolutionary studies. The family Hesperiidae (skippers) was traditionally viewed as a sister to other butterflies based on its moth-like morphology and darting flight habits with fast wing beats. However, DNA studies suggest that the family Papilionidae (swallowtails) may be the sister to other butterflies including skippers. The moth-like features and the controversial position of skippers in Lepidoptera phylogeny make them valuable targets for comparative genomics.
We obtained the 310 Mb draft genome of the Clouded Skipper (Lerema accius) from a wild-caught specimen using a cost-effective strategy that overcomes the high (1.6 %) heterozygosity problem. Comparative analysis of Lerema accius and the highly heterozygous genome of Papilio glaucus revealed differences in patterns of SNP distribution, but similarities in functions of genes that are enriched in non-synonymous SNPs. Comparison of Lepidoptera genomes revealed possible molecular bases for unique traits of skippers: a duplication of electron transport chain components could result in efficient energy supply for their rapid flight; a diversified family of predicted cellulases might allow them to feed on cellulose-enriched grasses; an expansion of pheromone-binding proteins and enzymes for pheromone synthesis implies a more efficient mate-recognition system, which compensates for the lack of clear visual cues due to the similarities in wing colors and patterns of many species of skippers. Phylogenetic analysis of several Lepidoptera genomes suggested that the position of Hesperiidae remains uncertain as the tree topology varied depending on the evolutionary model.
Completion of the first genome from the family Hesperiidae allowed comparative analyses with other Lepidoptera that revealed potential genetic bases for the unique phenotypic traits of skippers. This work lays the foundation for future experimental studies of skippers and provides a rich dataset for comparative genomics and phylogenetic studies of Lepidoptera.
蝴蝶和飞蛾正在成为遗传学和进化研究中的模式生物。弄蝶科（弄蝶）传统上被视为其他蝴蝶的姐妹类群，基于其类似飞蛾的形态和快速振翅的 darting 飞行习性。然而，DNA 研究表明，凤蝶科（凤蝶）可能是包括弄蝶在内的其他蝴蝶的姐妹类群。弄蝶类似飞蛾的特征以及它们在鳞翅目系统发育中存在争议的位置，使其成为比较基因组学的重要研究对象。
我们采用一种经济高效的策略，从一只野生捕获的样本中获得了云弄蝶（Lerema accius）的 310 Mb 基因组草图，该策略克服了高（1.6%）杂合度问题。对云弄蝶和北美黄凤蝶高度杂合的基因组进行比较分析，揭示了单核苷酸多态性（SNP）分布模式的差异，但在非同义 SNP 富集的基因功能方面存在相似性。鳞翅目基因组的比较揭示了弄蝶独特性状可能的分子基础：电子传递链成分的重复可能为其快速飞行提供高效的能量供应；一个多样化的预测纤维素酶家族可能使它们能够以富含纤维素的草为食；信息素结合蛋白和信息素合成酶的扩展意味着更高效的配偶识别系统，这弥补了许多弄蝶物种翅膀颜色和图案相似导致缺乏清晰视觉线索的不足。对几个鳞翅目基因组的系统发育分析表明，弄蝶科的位置仍然不确定，因为树形拓扑结构因进化模型而异。
弄蝶科首个基因组的完成使得与其他鳞翅目进行比较分析成为可能，揭示了弄蝶独特表型性状的潜在遗传基础。这项工作为未来对弄蝶科的实验研究奠定了基础，并为鳞翅目的比较基因组学和系统发育研究提供了丰富的数据集。
