Data from: Reproductive workers show queen-like gene expression in an intermediately eusocial insect, the buff-tailed bumble bee Bombus terrestris

Bumble bees represent a taxon with an intermediate level of eusociality within Hymenoptera. The clear division of reproduction between a single founding queen and the largely sterile workers is characteristic for highly eusocial species, whereas the morphological similarity between the bumble bee queen and the workers is typical for more primitively eusocial hymenopterans. Also, unlike other highly eusocial hymenopterans, division of labour among worker subcastes is plastic and not predetermined by morphology or age. We conducted a differential expression analysis based on RNA-seq data from 11 combinations of developmental stage and caste to investigate how a single genome can produce the distinct castes of queens, workers and males in the buff-tailed bumble bee Bombus terrestris. Based on expression patterns, we found males to be the most distinct of all adult castes (2411 transcripts differentially expressed compared to nonreproductive workers). However, only relatively few transcripts were differentially expressed between males and workers during development (larvae: 71 and pupae: 162). This indicates the need for more distinct expression patterns to control behaviour and physiology in adults compared to those required to create different morphologies. Among female castes, reproductive workers and their nonreproductive sisters displayed differential expression in over ten times more transcripts compared to the differential expression found between reproductive workers and their mother queen. This suggests a strong shift towards a more queenlike behaviour and physiology when a worker becomes fertile. This contrasts with eusocial species where reproductive workers are more similar to nonreproductive workers than the queen.熊蜂是膜翅目（Hymenoptera）内真社会性水平处于中间过渡阶段的类群。单只奠基蜂后与绝大多数不育工蜂之间明确的生殖分工，是高度真社会性（eusociality）物种的典型特征；而熊蜂蜂后与工蜂间的形态相似性，则是更为原始的真社会性膜翅目昆虫的典型特点。此外，与其他高度真社会性膜翅目昆虫不同，工蜂亚品级间的劳动分工具有可塑性，并非由形态或年龄预先决定。我们基于涵盖11种发育阶段与品级组合的RNA测序（RNA-seq）数据开展差异表达分析，旨在探究单套基因组如何在黄尾熊蜂（Bombus terrestris）中产生蜂后、工蜂与雄蜂三类截然不同的品级。基于基因表达模式分析，我们发现雄蜂是所有成虫品级中分化最为显著的类群：与非生殖型工蜂相比，其存在2411个差异表达转录本。但在发育阶段中，雄蜂与工蜂之间的差异表达转录本数量相对较少（幼虫期71个，蛹期162个）。这表明，相较于调控不同形态发育所需的表达模式，成虫阶段需要更为差异化的表达模式来调控行为与生理机能。在雌性品级中，生殖型工蜂与其非生殖型姊妹工蜂之间的差异表达转录本数量，是生殖型工蜂与其母蜂后之间差异表达转录本数量的十倍以上。这意味着当工蜂获得生殖能力后，其行为与生理会发生向蜂后表型的显著转变。这与那些生殖型工蜂相较于蜂后，更趋近于非生殖型工蜂的真社会性物种形成鲜明对比。