Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871, Copenhagen, Denmark.
Department of Ecology, Federal University of Rio Grande do Norte, Natal, 59078-900, Brazil.
Biol Rev Camb Philos Soc. 2018 Feb;93(1):555-573. doi: 10.1111/brv.12357. Epub 2017 Sep 13.
Heliconiines are called passion vine butterflies because they feed exclusively on Passiflora plants during the larval stage. Many features of Passiflora and heliconiines indicate that they have radiated and speciated in association with each other, and therefore this model system was one of the first examples used to exemplify coevolution theory. Three major adaptations of Passiflora plants supported arguments in favour of their coevolution with heliconiines: unusual variation of leaf shape within the genus; the occurrence of yellow structures mimicking heliconiine eggs; and their extensive diversity of defence compounds called cyanogenic glucosides. However, the protection systems of Passiflora plants go beyond these three features. Trichomes, mimicry of pathogen infection through variegation, and production of extrafloral nectar to attract ants and other predators of their herbivores, are morphological defences reported in this plant genus. Moreover, Passiflora plants are well protected chemically, not only by cyanogenic glucosides, but also by other compounds such as alkaloids, flavonoids, saponins, tannins and phenolics. Heliconiines can synthesize cyanogenic glucosides themselves, and their ability to handle these compounds was probably one of the most crucial adaptations that allowed the ancestor of these butterflies to feed on Passiflora plants. Indeed, it has been shown that Heliconius larvae can sequester cyanogenic glucosides and alkaloids from their host plants and utilize them for their own benefit. Recently, it was discovered that Heliconius adults have highly accurate visual and chemosensory systems, and the expansion of brain structures that can process such information allows them to memorize shapes and display elaborate pre-oviposition behaviour in order to defeat visual barriers evolved by Passiflora species. Even though the heliconiine-Passiflora model system has been intensively studied, the forces driving host-plant preference in these butterflies remain unclear. New studies have shown that host-plant preference seems to be genetically controlled, but in many species there is some plasticity in this choice and preferences can even be induced. Although much knowledge regarding the coevolution of Passiflora plants and heliconiine butterflies has accumulated in recent decades, there remain many exciting unanswered questions concerning this model system.
旋花蝶科蝴蝶被称为 passion vine 蝴蝶，因为它们在幼虫阶段只以 Passiflora 植物为食。Passiflora 和旋花蝶科的许多特征表明，它们彼此辐射并特化，因此这个模型系统是最早用来例证协同进化理论的例子之一。Passiflora 植物的三个主要适应性支持了它们与旋花蝶科协同进化的观点：属内叶片形状的异常变化；出现模仿旋花蝶科卵的黄色结构；以及它们广泛的防御化合物称为氰基葡萄糖苷。然而，Passiflora 植物的保护系统不仅仅局限于这三个特征。毛状体、通过斑驳模拟病原体感染的拟态，以及产生额外的花蜜以吸引其食草动物的蚂蚁和其他捕食者，是该植物属中报道的形态防御。此外，Passiflora 植物不仅受到氰基葡萄糖苷的化学保护，还受到其他化合物如生物碱、类黄酮、皂甙、单宁和酚类的化学保护。旋花蝶科蝴蝶自身能够合成氰基葡萄糖苷，而它们处理这些化合物的能力可能是这些蝴蝶祖先能够以 Passiflora 植物为食的最关键适应之一。事实上，已经表明，Heliconius 幼虫可以从它们的宿主植物中隔离出氰基葡萄糖苷和生物碱，并将其用于自身利益。最近，人们发现，成年 Heliconius 蝴蝶具有高度精确的视觉和化学感觉系统，并且大脑结构的扩展可以处理这些信息，使它们能够记住形状并表现出精心设计的产卵前行为，以击败 Passiflora 物种进化的视觉障碍。尽管旋花蝶科- Passiflora 模型系统已经得到了深入研究，但驱动这些蝴蝶对宿主植物偏好的力量仍不清楚。新的研究表明，宿主植物偏好似乎是由遗传控制的，但在许多物种中，这种选择存在一定的可塑性，甚至可以诱导偏好。尽管最近几十年积累了大量关于 Passiflora 植物和旋花蝶科蝴蝶协同进化的知识，但关于这个模型系统仍有许多令人兴奋的未解问题。
