How an organisms sensory system functions is central to how it navigates its environment and meets the behavioural challenges associated with survival and reproduction. Comparing sensory systems across species can reveal how facets of behaviour and ecology promote adaptive shifts in the relative importance of certain environmental cues. The insect olfactory system is prominent model for investigating how ecological factors impact sensory reception and processing. Notably work in Lepidoptera led to the discovery of vastly expanded structures, termed a macroglomerular complex (MGC), within the primary olfactory processing centre. These structures typically process pheromonal cues and provide a classic example of how variation in size can influence the functional processing of sensory cues. Though prevalent across moths, the MGC was lost during the early evolution of butterflies, consistent with evidence that courtship initiation in butterflies is primarily reliant upon visual cues, rather than long distance olfactory signals like pheromones. However, a MGC has recently been reported to be present in a species of ithomiine, Godryis zavaleta, suggesting this once lost neural adaptation has re-emerged in this clade. Here, we show that MGCs, or MGC-like morphologies, are indeed widely distributed across the ithomiine tribe, and vary in both structure and the prevalence of sexual dimorphism. Based on patterns of variation across species with different chemical ecologies, we suggest that this structure is involved in the processing of both plant and pheromonal cues, of interlinked chemical constitution, and has evolved in conjunction with the increased importance and diversification of plant derived chemicals cues in ithomiines.

中文翻译：

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依托米因蝴蝶的专门触角叶形态的重新出现和多样化

生物体感觉系统如何运作是其如何在环境中导航并应对与生存和繁殖相关的行为挑战的关键。比较物种间的感官系统可以揭示行为和生态的各个方面如何促进某些环境线索的相对重要性的适应性转变。昆虫嗅觉系统是研究生态因素如何影响感官接收和加工的杰出模型。鳞翅目的显着工作导致了在初级嗅觉处理中心内发现了一个巨大扩展的结构，称为巨球复合物（MGC）。这些结构通常处理信息素提示，并提供大小变化如何影响感官提示功能处理的经典示例。尽管在飞蛾中普遍存在，MGC在蝴蝶的早期进化过程中丢失了，这与有证据表明，蝴蝶求爱主要取决于视觉提示，而不是像信息素那样的长距离嗅觉信号有关。然而，最近有报道称，在硫氨酸的一个物种，Godryis zavaleta中存在一种MGC，这表明这种曾经失去的神经适应性已经重新出现在这个进化枝中。在这里，我们表明，MGC或类似MGC的形态确实在整个ithomiine部落中广泛分布，并且在结构和性二态性的患病率方面均存在差异。根据具有不同化学生态的物种间的变异模式，我们建议这种结构参与植物和信息素线索的处理，相互联系的化学成分，