Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.
Proc Natl Acad Sci U S A. 2013 Jul 2;110(27):11050-5. doi: 10.1073/pnas.1221781110. Epub 2013 Jun 10.
Polyphenism is the phenomenon in which alternative phenotypes are produced by a single genotype in response to environmental cues. An extreme case is found in social insects, in which reproductive queens and sterile workers that greatly differ in morphology and behavior can arise from a single genotype. Experimental evidence for maternal effects on caste determination, the differential larval development toward the queen or worker caste, was recently documented in Pogonomyrmex seed harvester ants, in which only colonies with a hibernated queen produce new queens. However, the proximate mechanisms behind these intergenerational effects have remained elusive. We used a combination of artificial hibernation, hormonal treatments, gene expression analyses, hormone measurements, and vitellogenin quantification to investigate how the combined effect of environmental cues and hormonal signaling affects the process of caste determination in Pogonomyrmex rugosus. The results show that the interplay between insulin signaling, juvenile hormone, and vitellogenin regulates maternal effects on the production of alternative phenotypes and set vitellogenin as a likely key player in the intergenerational transmission of information. This study reveals how hibernation triggers the production of new queens in Pogonomyrmex ant colonies. More generally, it provides important information on maternal effects by showing how environmental cues experienced by one generation can translate into phenotypic variation in the next generation.
多态现象是指单一基因型在环境线索的作用下产生不同表型的现象。在社会性昆虫中可以观察到一个极端的例子，在这些昆虫中，生殖蚁后和形态和行为差异很大的不育工蚁可以由单一基因型产生。最近在 Pogonomyrmex 种子采集蚁中发现了关于母性行为对等级决定的影响，即幼虫向蚁后或工蚁等级的不同发育的实验证据，这些蚁后只存在于休眠的蚁后群体中。然而，这些代际效应背后的直接机制仍然难以捉摸。我们使用人工休眠、激素处理、基因表达分析、激素测量和卵黄蛋白定量等方法，研究了环境线索和激素信号的综合作用如何影响 Pogonomyrmex rugosus 的等级决定过程。结果表明，胰岛素信号、保幼激素和卵黄蛋白之间的相互作用调节了母性行为对产生替代表型的影响，并将卵黄蛋白确定为信息代际传递的一个可能关键因素。这项研究揭示了冬眠如何触发 Pogonomyrmex 蚁群中产生新的蚁后。更普遍地说，它通过展示一代经历的环境线索如何转化为下一代的表型变异，为母性行为提供了重要信息。
