Host shifts and host-associated differentiation in herbivorous insects: ecological causes and consequences

地球上生命最明显的特征之一是其惊人的多样性-至少有100万种是科学已知的，也许还有多达3000万种有待发现。 然而，有些谱系比其他谱系更加多样化，而解释这种差异性成功是进化生态学中最基本的问题之一。 “高度多样性”最引人注目的例子是以植物为食的昆虫和攻击它们的拟寄生虫--多达一半的动物物种可能属于其中的一个群体。 植食性昆虫和拟寄生物进化成功的一个原因可能是它们倾向于进化出专门的饮食。 饮食通过宿主转移（向饮食中添加新的宿主植物）进化，然后通过宿主相关分化（HAD）进化新的多样性，其中单个饮食通才分化形成一对新的宿主专业物种。

One of the most obvious features of life on Earth is its astonishing diversity – at least a million species are known to science, and perhaps as many as 30 million more remain to be discovered. Some lineages have diversified much more abundantly than others, though, and accounting for this differential success is one of the most fundamental questions in evolutionary ecology. Among the most spectacular examples of “hyperdiversity” are plant-feeding insects and the parasitoids that attack them – as many as half of all animal species may belong to one or the other of these groups. One reason for the evolutionary success of plant-feeding insects and parasitoids may be their tendency to evolve specialized diets. Diets evolve via host-shifting (adding new host plants to diet), and then new diversity evolves by host-associated differentiation (HAD), in which a single diet generalist diverges to form a new pair of host-specialist species.