The queen‐worker caste system of eusocial insects represents a prime example of developmental polyphenism (environmentally‐induced phenotypic polymorphism) and is intrinsic to the evolution of advanced eusociality. However, the comparative molecular basis of larval caste determination and subsequent differentiation in the eusocial Hymenoptera remains poorly known. To address this issue within bees, we profiled caste‐associated gene expression in female larvae of the intermediately eusocial bumblebee Bombus terrestris. In B. terrestris, female larvae experience a queen‐dependent period during which their caste fate as adults is determined followed by a nutrition‐sensitive period also potentially affecting caste fate but for which the evidence is weaker. We used mRNA‐seq and qRT‐PCR validation to isolate genes differentially expressed between each caste pathway in larvae at developmental stages before and after each of these periods. We show that differences in gene expression between caste pathways are small in totipotent larvae, then peak after the queen‐dependent period. Relatively few novel (i.e., taxonomically‐restricted) genes were differentially expressed between castes, though novel genes were significantly enriched in late‐instar larvae in the worker pathway. We compared sets of caste‐associated genes in B. terrestris with those reported from the advanced eusocial honeybee, Apis mellifera, and found significant but relatively low levels of overlap of gene lists between the two species. These results suggest both the existence of low numbers of shared toolkit genes and substantial divergence in caste‐associated genes between Bombus and the advanced eusocial Apis since their last common eusocial ancestor.

中文翻译：

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中等社会性大黄蜂幼虫种姓确定和分化过程中的基因表达，以及与高级社会性蜜蜂的比较分析

真社会性昆虫的王后工种姓制度代表了发育多态性（环​​境诱导的表型多态性）的一个典型例子，并且是先进的真社会性进化所固有的。然而，在正常社会膜翅目中幼虫种姓确定和随后分化的比较分子基础仍然知之甚少。为了解决蜜蜂内部的这个问题，我们分析了中等社会性大黄蜂Bombus terrestris雌性幼虫中种姓相关的基因表达。在B中。土生土长的, 雌性幼虫经历了一个依赖女王的时期，在此期间它们成年后的种姓命运被决定，随后是营养敏感期，也可能影响种姓命运，但证据较弱。我们使用 mRNA-seq 和 qRT-PCR 验证来分离在每个发育阶段之前和之后在幼虫的每个种姓途径之间差异表达的基因。我们表明，种姓途径之间的基因表达差异在全能幼虫中很小，然后在女王依赖期后达到峰值。相对较少的新基因（即分类限制）在种姓之间差异表达，尽管新基因在工人途径的晚龄幼虫中显着富集。我们比较了B中的种姓相关基因集。土生土长的与来自先进的社会性蜜蜂（Apis mellifera ）的报道相一致，发现两个物种之间基因列表的重叠程度显着但相对较低。这些结果表明，自它们最后一个共同的真社会祖先以来，熊蜂和先进的真社会蜜蜂之间存在少量共享工具包基因和种姓相关基因的显着差异。