Data from: Conservation and modification of genetic and physiological toolkits underpinning diapause in bumble bee queens

Diapause is the key adaptation allowing insects to survive unfavorable conditions and inhabit an array of environments. Physiological changes during diapause are largely conserved across species, and are hypothesized to be regulated by a conserved suite of genes (a “toolkit”). Furthermore, it is hypothesized that in social insects, this toolkit was co-opted to mediate caste differentiation between long-lived, reproductive, diapause-capable queens and short-lived, sterile workers. Using Bombus terrestris queens we examined the physiological and transcriptomic changes associated with diapause and CO2 treatment, which causes queens to bypass diapause. We performed comparative analyses with genes previously identified to be associated with diapause in the Dipteran Sarcophaga crassipalpis and with caste differentiation in bumble bees. As in Diptera, diapause in bumble bees is associated with physiological and transcriptional changes related to nutrient storage, stress resistance and core metabolic pathways. There is a significant overlap, both at the level of transcript and gene ontology, between the genetic mechanisms mediating diapause in B. terrestris and S. crassipalpis, reaffirming the existence of a conserved insect diapause genetic toolkit. However, a substantial proportion (10%) of the differentially regulated transcripts in diapausing queens have no clear orthologs in other species, and key players regulating diapause in Diptera (juvenile hormone and vitellogenin) appear to have distinct functions in bumble bees. We also found a substantial overlap between genes related to caste determination and diapause in bumble bees. Thus, our studies demonstrate an intriguing interplay between pathways underpinning adaptation to environmental extremes and the evolution of sociality in insects.

滞育（diapause）是昆虫得以在不利环境中存活并占据多样生境的关键适应性策略。昆虫滞育过程中的生理变化在多个物种间整体保守，且被推测由一套保守的基因集合（即"基因工具箱"）调控。此外，有假说提出在社会性昆虫中，这套基因工具箱被招募以调控长寿、可繁殖且具备滞育能力的蜂王，与短命、不育的工蜂之间的级型分化。本研究以西方熊蜂（Bombus terrestris）蜂王为实验材料，检测了与滞育以及可促使蜂王绕过滞育的二氧化碳处理相关的生理和转录组变化。我们将实验结果与此前在双翅目（Diptera）昆虫肥须亚麻蝇（Sarcophaga crassipalpis）中鉴定出的滞育相关基因，以及熊蜂级型分化相关基因进行了比较分析。与双翅目昆虫一致，熊蜂的滞育同样伴随与营养储存、抗逆性以及核心代谢通路相关的生理与转录组变化。在转录本与基因本体论（gene ontology）层面，西方熊蜂与肥须亚麻蝇的滞育调控遗传机制均存在显著重叠，这再次证实了昆虫滞育保守基因工具箱的存在。不过，滞育蜂王体内10%的差异表达转录本在其他物种中未发现明确的同源基因，且双翅目昆虫中调控滞育的关键因子——保幼激素（juvenile hormone）与卵黄原蛋白（vitellogenin）——在熊蜂中似乎发挥着截然不同的功能。我们还发现熊蜂中与级型决定相关的基因与滞育相关基因存在大量重叠。综上，本研究揭示了支撑昆虫应对极端环境的适应性通路与社会性演化之间存在有趣的相互作用。