Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Ulm, Germany.
General Zoology, Institute for Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
J Chem Ecol. 2021 May;47(4-5):406-419. doi: 10.1007/s10886-021-01267-w. Epub 2021 Mar 31.
In eusocial insects, chemical communication is crucial for mediating many aspects of social activities, especially the regulation of reproduction. Though queen signals are known to decrease ovarian activation of workers in highly eusocial species, little is known about their evolution. In contrast, some primitively eusocial species are thought to control worker reproduction through physical aggression by the queen rather than via pheromones, suggesting the evolutionary establishment of chemical signals with more derived sociality. However, studies supporting this hypothesis are largely missing. Socially polymorphic halictid bees, such as Halictus rubicundus, with social and solitary populations in both Europe and North America, offer excellent opportunities to illuminate the evolution of caste-specific signals. Here we compared the chemical profiles of social and solitary populations from both continents and tested whether (i) population or social level affect chemical dissimilarity and whether (ii) caste-specific patterns reflect a conserved queen signal. Our results demonstrate unique odor profiles of European and North American populations, mainly due to different isomers of n-alkenes and macrocyclic lactones; chemical differences may be indicative of phylogeographic drift in odor profiles. We also found common compounds overproduced in queens compared to workers in both populations, indicating a potential conserved queen signal. However, North American populations have a lower caste-specific chemical dissimilarity than European populations which raises the question if both use different mechanisms of regulating reproductive division of labor. Therefore, our study gives new insights into the evolution of eusocial behavior and the role of chemical communication in the inhibition of reproduction.
在真社会性昆虫中，化学通讯对于调节许多社会活动方面至关重要，尤其是对生殖的调节。虽然已经知道女王信号可以降低高度真社会性物种中工蜂的卵巢激活，但对其进化知之甚少。相比之下，一些原始真社会性物种被认为通过女王的身体攻击而不是信息素来控制工蜂的繁殖，这表明通过更具衍生性的社会性来建立化学信号的进化。然而，支持这一假设的研究在很大程度上是缺失的。社会性多态性叶蜂，如 Halictus rubicundus，在欧洲和北美的社会和独居种群中都有，为阐明特定级型信号的进化提供了极好的机会。在这里，我们比较了来自两个大陆的社会性和独居种群的化学特征，并测试了（i）种群或社会水平是否会影响化学差异，以及（ii）是否特定级型的模式反映了保守的女王信号。我们的研究结果表明，欧洲和北美的种群具有独特的气味特征，主要是由于 n-烯烃和大环内酯的不同异构体；化学差异可能表明气味特征存在系统地理漂移。我们还发现，与两个种群中的工蜂相比，女王中过度产生的共同化合物表明存在潜在的保守女王信号。然而，与欧洲种群相比，北美种群的特定级型化学差异较低，这引发了一个问题，即两者是否使用不同的机制来调节生殖劳动分工。因此，我们的研究为真社会性行为的进化以及化学通讯在抑制生殖中的作用提供了新的见解。
