Southwood T R
Ciba Found Symp. 1984;102:138-51. doi: 10.1002/9780470720837.ch9.
The adaptation of insects to plants probably commenced in the early Permian period, though most current associations will be more recent. A major burst of adaptation must have followed the rise of the Angiosperms in the Cretaceous period, though some particular associations are as recent as this century. Living plants form a large proportion of the potential food in most habitats, though insects have had to overcome certain general hurdles to live and feed on them. Insects affect the reproduction and survival of plants, and thus the diversity of plant secondary chemicals may have evolved as a response. Where an insect species has a significant effect on a plant species that is its only host, coevolution may be envisaged. A spectacular example is provided by Heliconius butterflies and passion flower vines, studied by L.E. Gilbert and others. But such cases may be likened to 'vortices in the evolutionary stream': most plant species are influenced by a range of phytophagous insects so that selection will be for general defences--a situation termed diffuse coevolution. Evidence is presented on recent host-plant shifts to illustrate both the restrictions and the flexibility in current insect-plant associations.
昆虫对植物的适应可能始于二叠纪早期，不过目前大多数的共生关系形成时间更近。在白垩纪被子植物兴起之后，必定出现了一次适应的大爆发，尽管有些特定的共生关系近至本世纪才形成。在大多数栖息地中，活植物构成了潜在食物的很大一部分，不过昆虫必须克服某些普遍障碍才能以它们为食并生存。昆虫会影响植物的繁殖和存活，因此植物次生化学物质的多样性可能是作为一种应对措施而进化出来的。如果一个昆虫物种对其唯一寄主的植物物种有重大影响，那么可以设想会发生协同进化。L.E. 吉尔伯特等人研究的黑脉金斑蝶和西番莲藤蔓就是一个引人注目的例子。但这类情况可能类似于 “进化长河中的漩涡”：大多数植物物种受到一系列植食性昆虫的影响，因此选择会倾向于普遍防御——这种情况被称为扩散协同进化。文中给出了近期寄主植物转移的证据，以说明当前昆虫与植物共生关系中的限制因素和灵活性。
