Experimental niche evolution in seed beetles: Simulating responses to climate change in a currently evolving global crop pest

种子甲虫的实验生态位进化：模拟当前不断演变的全球作物害虫对气候变化的反应

• 批准号: 1654640
• 金额: --
• 依托单位: University of Aberdeen
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1654640
• 关键词: Experimental; niche; evolution; seed; beetles

Climates are currently changing at an unprecedented rate, and many organisms are responding to these changes with dramatic range shifts involving evolutionary responses. Among the organisms most strongly affected by changing climates are small, exothermic animals such as insects, which can evolve rapidly and quickly disperse into available niches, often posing new threats to food security (as crop or stored-food pests), human and animal welfare (as disease vectors), and affecting overall ecosystem function.1 The mechanisms of evolution and range shift under rapidly changing climates remain poorly understood. One question relates to the order of trait divergence, which has important consequences for how biodiversity is affected by environmental change. In a model of a-niche priority for population divergence, organisms first evolve traits related to their within-community niche (i.e., the a-niche), such as alternative patterns of resource-utilization, species-interaction, and microhabitat use. New ways of interacting with their local habitat may then facilitate range expansion by providing new ways to overcome prior geographic limitations. Conversely, under b-niche priority, environmental change induces range shifts (i.e., adaptation to novel habitats and locales, the b-niche) prior to or in lieu of local, a-niche differentiation.2 These alternative scenarios each have important implications for how organisms respond to changing climates over the long term. b-priority implies limited scope for fine-scale local adaptation, which may limit the success of organisms that have nowhere suitable to go as climates change, while a-priority suggests that climate change may trigger successful invasions and adaptive radiations. Each of these scenarios has been found to occur in a variety of natural systems, but the general conditions favouring each evolutionary pathway are currently unknown. In this PhD project, the student will investigate conditions under which these alternative niche evolution scenarios may occur, using experimental evolution under quasi-natural selection in a captive lab colony of seed beetles (Coleoptera: Bruchidae). Seed beetles are major pests on stored legumes and grains worldwide, and have been shown to evolve local host-plant shifts (habitat utilization, an a-niche component) and range shifts associated with evolving thermal tolerances (a b-niche component) in response to changing climates.3 Dynamic models developed by Jörgen Ripa (Lund University) suggest that the priority of a- vs. b-niche evolution depends on the relative strengths of evolutionary trade-offs imposed by habitat shifts vs. alternative resource use, and also by dispersal capacities. The student will conduct experimental evolution of replicate lineages in a two-habitat scenario with connectivity, where habitats are characterized by alternative thermal regimes. Within each habitat, individuals will also have the opportunity to adapt to new resources (i.e., new seed types). Rates of climate change within habitats, population densities, dispersal rates between habitats, and prior adaptations of initial lineages will be independently manipulated. Dynamic models of niche evolution pathways developed by Jörgen Ripa will inform experiments, and our experimental results will refine and parameterize future models. Controlled crossing experiments of resulting lineages will indicate the quantitative genetic basis of niche divergence along habitat and resource utilization axes, providing a mechanistic explanation for observed patterns. The project can also be further developed to incorporate genomic methods for understanding the mechanisms of niche evolution. The outputs of this project will further evolutionary theory, particularly in the area of niche evolution, and will inform pest management decisions.

气候目前正在以前所未有的速度变化，许多生物体正在对这些变化做出反应，这些变化涉及进化反应的戏剧性范围变化。受气候变化影响最大的生物体是昆虫等小型发热动物，它们可以迅速进化并迅速分散到现有的生态位中，往往对粮食安全（作为作物或储存粮食的害虫）、人类和动物福利（作为疾病媒介）构成新的威胁，并影响整个生态系统的功能。一个问题涉及性状差异的顺序，这对生物多样性如何受到环境变化的影响具有重要影响。在种群分化的生态位优先模型中，生物首先进化出与其群落内生态位相关的性状（即，a-生态位），如资源利用的替代模式，物种相互作用和微生境利用。与当地栖息地相互作用的新方式可能会通过提供新的方法来克服先前的地理限制，从而促进范围的扩大。相反，在b-生态位优先下，环境变化引起范围转移（即，2这些备选方案对生物如何长期应对气候变化具有重要影响。b-优先意味着小规模地方适应的范围有限，这可能会限制生物体的成功，因为它们在气候变化时无处可去，而a-优先意味着气候变化可能会引发成功的入侵和适应性辐射。这些情景中的每一种都被发现发生在各种自然系统中，但目前还不知道有利于每一种进化途径的一般条件。在这个博士项目中，学生将调查这些替代生态位进化情景可能发生的条件，在种子甲虫（鞘翅目：豆象科）的圈养实验室殖民地中使用准自然选择下的实验进化。种子甲虫是世界范围内储存豆类和谷物的主要害虫，并已被证明可以进化本地寄主植物转移（栖息地利用，a-小生境成分）和与发展中的热耐受性相关的范围偏移3 Jörgen Ripa开发的动态模型（隆德大学）提出，a-生态位与b-生态位进化的优先级取决于生境变化与替代资源利用以及扩散能力所施加的进化权衡的相对强度。学生将在具有连通性的两个栖息地场景中进行复制谱系的实验进化，其中栖息地的特点是替代热制度。在每个栖息地内，个体也将有机会适应新的资源（即，新的种子类型）。栖息地内的气候变化率，人口密度，栖息地之间的扩散率，以及初始谱系的先前适应将被独立操纵。由Jörgen Ripa开发的生态位进化途径的动态模型将为实验提供信息，我们的实验结果将完善和参数化未来的模型。控制杂交实验所产生的谱系将指示生态位分歧的数量遗传基础沿着生境和资源利用轴，提供了一个机制解释所观察到的模式。该项目还可以进一步发展，以纳入基因组方法，了解生态位进化的机制。该项目的成果将进一步发展进化理论，特别是在生态位进化领域，并将为害虫管理决策提供信息。