Data from: The genomes of two key bumblebee species with primitive eusocial organisation

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation.研究背景：从独居行为向社会行为的转变是演化历程中的关键过渡事件之一。原始真社会性（eusocial）熊蜂为阐释高度真社会性昆虫社会的演化提供了绝佳的研究模型。熊蜂同时也是极具价值的自然与农业传粉昆虫，部分物种近期的种群衰退已引发广泛关注。高质量的基因组数据将为熊蜂生物学的诸多核心问题提供研究支撑，包括其对已被关联的种群生存力威胁的易感性。 研究结果：本研究报道了两种生态优势显著且被广泛应用于科研的熊蜂——大地熊蜂（Bombus terrestris）与茄熊蜂（Bombus impatiens）的高质量基因组草图。将这两份全新基因组与高度真社会性的西方蜜蜂（Apis mellifera）及其他膜翅目（Hymenoptera）昆虫的基因组进行比对后，我们不仅发现了高度保守的同源序列，还鉴定出了对这类昆虫生物学特性至关重要的特有演化特征。部分被认为是支撑西方蜜蜂高级真社会性的基因组特征，同样存在于熊蜂基因组中，这表明蜜蜂谱系中的高级真社会性演化起源更早。熊蜂与西方蜜蜂的异生物质解毒（xenobiotic detoxification）基因与免疫基因同样呈现基因家族贫乏的特征，而与社会组织相关的多类基因（包括发育与行为相关基因）则表现出高度保守性。本次研究鉴定出的关键差异包括：熊蜂的化学感受（chemoreception）系统更偏向味觉（gustation）而非嗅觉（olfaction），以及二者在微小RNA（microRNAs）层面存在显著差异，这些差异可能参与调控社会组织及其他性状相关的基因表达。 研究结论：这两份熊蜂基因组为针对这类关键传粉昆虫及昆虫社会的后基因组学研究奠定了坚实基础。总体而言，基因组成数据表明，蜜蜂向高级真社会性演化的路径是通过众多基因与生物学过程中的微小改变实现的，而非依赖于显著的基因家族扩张或收缩。