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特征。滞育过程中的生理变化在各物种间大体保守，且被推测由一套保守的基因组合（即“工具箱”）调控。此外，有假说提出，在社会性昆虫中，这套基因工具箱被重新招募，以介导长寿、可繁殖且具备滞育能力的蜂后，与短命、无繁殖能力的工蜂之间的级型分化。本研究以地熊蜂（Bombus terrestris）蜂后为实验材料，探究了与滞育及CO₂处理相关的生理和转录组变化——其中CO₂处理可促使蜂后绕过滞育程序。我们结合此前在双翅目昆虫肥须亚麻蝇（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开展了比较分析。与双翅目昆虫类似，地熊蜂的滞育同样伴随与营养储存、抗逆性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（gene ontology，GO）层面，地熊蜂与肥须亚麻蝇的滞育调控遗传机制均存在显著重叠，这进一步证实了保守的昆虫滞育遗传工具箱的存在。不过，滞育蜂后体内10%的差异调控转录本在其他物种中并无明确的直系同源基因，且双翅目昆虫中调控滞育的关键因子——保幼激素与卵黄原蛋白——在熊蜂中似乎行使着截然不同的功能。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适应极端环境的通路，与昆虫社会性演化之间存在着引人关注的相互作用。