Eltz Thomas, Zimmermann Yvonne, Pfeiffer Carolin, Pech Jorge Ramirez, Twele Robert, Francke Wittko, Quezada-Euan J Javier G, Lunau Klaus
Department of Neurobiology, University of Düsseldorf, 40225 Düsseldorf, Germany.
Curr Biol. 2008 Dec 9;18(23):1844-8. doi: 10.1016/j.cub.2008.10.049.
Saltational changes may underlie the diversification of pheromone communication systems in insects, which are normally under stabilizing selection favoring high specificity in signals and signal perception. In orchid bees (Euglossini), the production of male signals depends on the sense of smell: males collect complex blends of volatiles (perfumes) from their environment, which are later emitted as pheromone analogs at mating sites. We analyzed the behavioral and antennal response to perfume components in two male morphotypes of Euglossa cf. viridissima from Mexico, which differ in the number of mandibular teeth. Tridentate males collected 2-hydroxy-6-nona-1,3-dienyl-benzaldehyde (HNDB) as the dominant component of their perfume. In bidentate males, blends were broadly similar but lacked HNDB. Population genetic analysis revealed that tri- and bidentate males belong to two reproductively isolated lineages. Electroantennogram tests (EAG and GC-EAD) showed substantially lower antennal responses to HNDB in bidentate versus tridentate males, revealing for the first time a mechanism by which closely related species acquire different chemical compounds from their habitat. The component-specific differences in perfume perception and collection in males of two sibling species are in agreement with a saltational, olfaction-driven mode of signal perfume evolution. However, the response of females to the diverged signals remains unknown.
跳跃式变化可能是昆虫信息素通讯系统多样化的基础，而昆虫信息素通讯系统通常处于稳定选择之下，这种选择有利于信号及信号感知具有高特异性。在兰花蜂（ Euglossini）中，雄性信号的产生依赖嗅觉：雄性从周围环境中收集复杂的挥发性混合物（香料），之后在交配地点将其作为信息素类似物释放出来。我们分析了来自墨西哥的两种 Euglossa cf. viridissima雄性形态型对香料成分的行为和触角反应，这两种形态型在下颚齿数上有所不同。具三齿的雄性收集2-羟基-6-壬-1,3-二烯基苯甲醛（HNDB）作为其香料的主要成分。在具两齿的雄性中，混合物大致相似，但缺少HNDB。群体遗传学分析表明，具三齿和具两齿的雄性属于两个生殖隔离的谱系。触角电图测试（EAG和GC-EAD）显示，具两齿的雄性对HNDB的触角反应明显低于具三齿的雄性，首次揭示了近缘物种从其栖息地获取不同化合物的一种机制。两个亲缘关系相近物种的雄性在香料感知和收集方面的成分特异性差异，与信号香料进化的跳跃式、嗅觉驱动模式相一致。然而，雌性对分化信号的反应仍然未知。
