Caste differentiation involves many functional traits that diverge during larval growth and metamorphosis to produce adults irreversibly adapted to reproductive division of labor. Investigating developmental differentiation is important for general biological understanding and has increasingly been explored for social phenotypes that diverge in parallel from similar genotypes. Here, we use Monomorium pharaonis ants to investigate the extent to which canalized worker development can be shifted toward gyne (virgin-queen) phenotypes by juvenile hormone (JH) treatment. We show that excess JH can activate gyne-biased development in workers so that wing-buds, ocelli, antennal and genital imaginal discs, flight muscles, and gyne-like fat bodies and brains emerge after pupation. However, ovary development remained unresponsive to JH treatment, indicating that JH-sensitive germline sequestration happens well before somatic differentiation. Our findings reveal important qualitative restrictions in the extent to which JH treatment can redirect larval development and that these constraints are independent of body size. Our findings corroborate that JH is a key hormone for inducing caste differentiation but show that this process can be asymmetric for higher colony-level germline versus somatic caste differentiation in superorganisms as defined a century ago by Wheeler. We quantified gene expression changes in response to JH treatment throughout development and identified a set of JH-sensitive genes responsible for the emergence of gyne-like somatic traits. Our study suggests that the gonadotropic role of JH in ovary maturation has shifted from the individual level in solitary insects to the colony level in an evolutionary-derived and highly polygynous superorganism like the pharaoh ant.

中文翻译：

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保幼激素是蚂蚁不对称种姓分化的关键调节因子


种姓分化涉及许多功能性状，这些性状在幼虫生长和过程中发生分化，以产生不可逆地适应生殖分工的成虫。研究发育分化对于一般生物学理解很重要，并且越来越多地探索与相似基因型平行分化的社会表型。在这里，我们使用 Monomorium pharaonis 蚂蚁来研究通过幼年激素 （JH） 治疗，管道化工蚁发育在多大程度上可以转变为 gyne （处女-女王） 表型。我们表明，过量的 JH 可以激活工人的 gyne 偏向发育，从而在化蛹后出现翼芽、ocelli、触角和生殖器假想盘、飞行肌肉以及类似 gyne 的脂肪体和大脑。然而，卵巢发育对 JH 治疗仍然无反应，表明 JH 敏感的种系隔离发生在体细胞分化之前。我们的研究结果揭示了 JH 治疗在多大程度上可以重定向幼虫发育的重要定性限制，并且这些限制与体型无关。我们的研究结果证实 JH 是诱导种姓分化的关键激素，但表明这个过程对于一个世纪前 Wheeler 定义的超级生物中更高的菌落水平种系与体细胞种姓分化可能是不对称的。我们量化了整个发育过程中响应 JH 治疗的基因表达变化，并确定了一组导致 gyne 样体细胞性状出现的 JH 敏感基因。 我们的研究表明，JH 在卵巢成熟的促性腺作用已经从独居昆虫的个体水平转变为像法老蚁这样进化衍生且高度多夫多妻制的超有机体的群体水平。