Social regulation of insulin signaling and the evolution of eusociality in ants.

Queens and workers of eusocial Hymenoptera are considered homologous to the reproductive and brood care phases of an ancestral subsocial lifecycle. However, the molecular mechanisms underlying the evolution of reproductive division of labor remain obscure. Using a brain transcriptomics screen, we identified a single gene, insulin-like peptide 2 (ilp2), which is always upregulated in ant reproductives, likely due to their higher nutritional state. In clonal raider ants, larval signals inhibit adult reproduction by suppressing ilp2, producing a colony reproductive cycle reminiscent of ancestral subsociality. Increasing ILP2 peptide levels overrides larval suppression, thereby breaking the colony cycle and inducing a stable division of labor. This suggests a simple model for the origin of ant eusociality via nutritionally determined reproductive asymmetries potentially amplified by larval signals.

真社会性膜翅目昆虫的蚁后和工蚁被认为与祖先亚社会性生命周期中的繁殖和育幼阶段是同源的。然而，生殖分工进化背后的分子机制仍然不清楚。通过一项脑部转录组学筛选，我们鉴定出了一个基因，即胰岛素样肽2（ilp2），它在蚂蚁的繁殖个体中总是上调的，这可能是由于它们较高的营养状态。在克隆掠夺蚁中，幼虫信号通过抑制ilp2来抑制成虫繁殖，产生一个类似于祖先亚社会性的蚁群繁殖周期。增加ILP2肽水平会克服幼虫的抑制作用，从而打破蚁群周期并诱导稳定的分工。这表明了一个关于蚂蚁真社会性起源的简单模型，即通过营养决定的生殖不对称性，并可能被幼虫信号放大。