Hunt James H, Kensinger Bart J, Kossuth Jessica A, Henshaw Michael T, Norberg Kari, Wolschin Florian, Amdam Gro V
Department of Biology, University of Missouri, St. Louis, MO 63121, USA.
Proc Natl Acad Sci U S A. 2007 Aug 28;104(35):14020-5. doi: 10.1073/pnas.0705660104. Epub 2007 Aug 17.
Colonies of social wasps, ants, and bees are characterized by the production of two phenotypes of female offspring, workers that remain at their natal nest and nonworkers that are potential colony reproductives of the next generation. The phenotype difference includes morphology and is fixed during larval development in ants, honey bees, and some social wasps, all of which represent an advanced state of sociality. Paper wasps (Polistes) lack morphological castes and are thought to more closely resemble an ancestral state of sociality wherein the phenotype difference between workers and nonworkers is established only during adult life. We address an alternative hypothesis: a bias toward the potential reproductive (gyne) phenotype among Polistes female offspring occurs during larval development and is based on a facultatively expressed ancestral life history trait: diapause. We show that two signatures of diapause (extended maturation time and enhanced synthesis and sequestration of a hexameric storage protein) characterize the development of gyne offspring in Polistes metricus. Hexameric storage proteins are implicated in silencing juvenile hormone signaling, which is a prerequisite for diapause. Diverging hexamerin protein dynamics driven by changes in larval provisioning levels thereby provide one possible mechanism that can cause an adaptive shift in phenotype bias during the Polistes colony cycle. This ontogenetic basis for alternative female phenotypes in Polistes challenges the view that workers and gynes represent behavior options equally available to every female offspring, and it exemplifies how social insect castes can evolve from casteless lineages.
社会性黄蜂、蚂蚁和蜜蜂的群体具有两个特点，即会产生两种表型的雌性后代：留在出生巢穴的工蜂，以及作为下一代潜在群体繁殖者的非工蜂。这种表型差异包括形态学上的差异，并且在蚂蚁、蜜蜂和一些社会性黄蜂的幼虫发育过程中就已确定，所有这些都代表了社会性的高级状态。纸巢蜂（Polistes）没有形态学上的等级分化，被认为更接近社会性的原始状态，在这种状态下，工蜂和非工蜂之间的表型差异仅在成年期才得以确立。我们提出了另一种假设：纸巢蜂雌性后代中对潜在繁殖型（雌蜂）表型的偏向在幼虫发育过程中就已出现，并且是基于一种可选择性表达的原始生活史特征：滞育。我们发现滞育的两个特征（延长的成熟时间以及六聚体储存蛋白合成和封存的增强）表征了米氏纸巢蜂（Polistes metricus）雌蜂后代的发育过程。六聚体储存蛋白与抑制保幼激素信号传导有关，而保幼激素信号传导被抑制是滞育的一个先决条件。幼虫营养供应水平的变化所驱动的六聚蛋白动态变化，从而提供了一种可能的机制，该机制能够在纸巢蜂群体周期中引起表型偏向的适应性转变。纸巢蜂中雌性替代表型的这种个体发育基础，挑战了工蜂和雌蜂代表每个雌性后代都同样可获得的行为选择这一观点，并且它例证了社会性昆虫的等级分化是如何从无等级分化的谱系中演化而来的。
