Max Planck Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Hans-Knoell-Strasse 8, D-07745, Jena, Germany.
Max Planck Institute for Chemical Ecology, Department of Entomology, Hans-Knoell-Strasse 8, D-07745, Jena, Germany.
Sci Rep. 2020 Feb 7;10(1):2125. doi: 10.1038/s41598-020-59063-7.
An animal's fitness strongly depends on successful feeding, avoidance of predators and reproduction. All of these behaviours commonly involve chemosensation. As a consequence, when species' ecological niches and life histories differ, their chemosensory abilities need to be adapted accordingly. The intertidal insect Clunio marinus (Diptera: Chironomidae) has tuned its olfactory system to two highly divergent niches. The long-lived larvae forage in a marine environment. During the few hours of terrestrial adult life, males have to find the female pupae floating on the water surface, free the cryptic females from their pupal skin, copulate and carry the females to the oviposition sites. In order to explore the possibility for divergent olfactory adaptations within the same species, we investigated the chemosensory system of C. marinus larvae, adult males and adult females at the morphological and molecular level. The larvae have a well-developed olfactory system, but olfactory gene expression only partially overlaps with that of adults, likely reflecting their marine vs. terrestrial lifestyles. The olfactory system of the short-lived adults is simple, displaying no glomeruli in the antennal lobes. There is strong sexual dimorphism, the female olfactory system being particularly reduced in terms of number of antennal annuli and sensilla, olfactory brain centre size and gene expression. We found hints for a pheromone detection system in males, including large trichoid sensilla and expression of specific olfactory receptors and odorant binding proteins. Taken together, this makes C. marinus an excellent model to study within-species evolution and adaptation of chemosensory systems.
动物的适应能力主要取决于觅食成功、躲避捕食者和繁殖。所有这些行为通常都涉及化学感觉。因此，当物种的生态位和生活史不同时，它们的化学感觉能力需要相应地适应。潮间带昆虫 Clunio marinus（双翅目：摇蚊科）已经调整了其嗅觉系统以适应两个高度不同的生态位。长寿的幼虫在海洋环境中觅食。在陆地成虫生命的几个小时内，雄性必须找到漂浮在水面上的雌性蛹，从蛹皮中释放出隐藏的雌性，交配并将雌性带到产卵地点。为了探索同一物种内嗅觉适应差异的可能性，我们在形态和分子水平上研究了 C. marinus 幼虫、成年雄性和成年雌性的化学生态系统。幼虫具有发达的嗅觉系统，但嗅觉基因表达与成虫部分重叠，可能反映了它们的海洋与陆地生活方式。短暂成虫的嗅觉系统很简单，触角叶中没有神经节。存在强烈的性别二态性，雌性嗅觉系统在触角环的数量、感觉器官、嗅觉脑中心大小和基因表达方面特别减少。我们在雄性中发现了一种信息素检测系统的迹象，包括大型毛形感觉器官和特定嗅觉受体和气味结合蛋白的表达。总之，这使得 C. marinus 成为研究化学感觉系统种内进化和适应的绝佳模型。
