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

草食昆虫的宿主转移和宿主相关分化：生态原因和后果

• 批准号: RGPIN-2015-04418
• 负责人: Heard, Stephen
• 金额: $ 2.91万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612957
• 关键词: Host; shifts; host; associated; differentiation

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.       While host-shifting and HAD are common, they are not universal, and different lineages can undergo these processes at different times and rates and by different mechanisms. My research program seeks to understand the ecological factors that control the occurrence of host-shifting and HAD, by studying the diverse set of insects feeding on two common Canadian goldenrods. By contrasting the ecology and population genetics of species that are evolving pairs of host specialists, vs. those that continue to feed as generalists, we can test hypotheses about forces that favour or retard diversification. Our current focus is on the way insect preferences for trait variation among host plant individuals can drive their evolutionary response to variation between host plant species. A predictive understanding of host-shifting and HAD will help us understand the origin of Earth’s biodiversity, as well as to anticipate and manage attack by insects on novel hosts in agricultural and agroforestry systems. We will also build on our HAD work by testing the hypothesis that the impact of herbivores on their host plants lessens over evolutionary time, as the plants evolve greater tolerance and the insects reduced virulence. If this is true, novel insect-herbivore associations generated by host-shifting and HAD should show higher impact than ancient ones. This is important, because such novel insect-herbivore associations also result from the spread of invasive species and have enormous and increasing ecological and economic costs worldwide.

地球上生命最明显的特征之一就是其惊人的多样性——科学界已知的至少有 100 万个物种，或许还有多达 3000 万个物种有待发现。然而，有些谱系的多样性比其他谱系丰富得多，而解释这种不同的成功是进化生态学中最基本的问题之一。 “超多样性”最引人注目的例子是以植物为食的昆虫和攻击它们的寄生蜂——所有动物物种中多达一半可能属于这些类群中的一个或另一个。植物性昆虫和寄生蜂进化成功的原因之一可能是它们进化出专门饮食的倾向。食性通过宿主转移（在食性中添加新的寄主植物）而进化，然后通过宿主相关分化（HAD）进化出新的多样性，其中单一食性通才分化形成一对新的寄主-专长物种。       虽然宿主转移和 HAD 很常见，但它们并不普遍，不同的谱系可以以不同的时间和速率通过不同的机制经历这些过程。我的研究项目旨在通过研究以两种常见的加拿大一枝黄花为食的多种昆虫，了解控制寄主转移和 HAD 发生的生态因素。通过对比正在进化的成对宿主专家物种与那些继续以通才形式进食的物种的生态学和群体遗传学，我们可以检验有关有利于或阻碍多样化的力量的假设。我们目前的重点是昆虫对寄主植物个体之间性状变异的偏好如何驱动它们对寄主植物物种之间变异的进化反应。对宿主转移和 HAD 的预测性理解将帮助我们了解地球生物多样性的起源，以及预测和管理昆虫对农业和农林业系统中新宿主的攻击。我们还将在 HAD 工作的基础上测试以下假设：食草动物对其寄主植物的影响随着进化时间的推移而减弱，因为植物进化出更强的耐受性，而昆虫则降低了毒力。如果这是真的，那么由宿主转移和 HAD 产生的新型昆虫与食草动物关联应该比古代的关联表现出更大的影响。这很重要，因为这种新颖的昆虫-草食动物关联也是入侵物种传播的结果，并且在全世界范围内造成巨大且不断增加的生态和经济成本。