The evolution of mimicry in a changing world: how shifting bumblebee communities affect selection on a colour-polymorphic hoverfly

全球气候变化、栖息地丧失和入侵物种的影响是对经济和生态上重要的传粉媒介（包括蜜蜂和食蚜蝇）的主要威胁。物种范围、灭绝和定殖事件的变化将改变群落组成，对生物多样性和生态系统服务产生多方面的影响。我们预测这些影响的能力受到自然生态系统复杂性的阻碍：物种在生态上相互作用，共同进化，因此物种对环境变化的反应不能孤立地估计。在这个项目中，我们将探索在环境变化的背景下，一个重要的传粉者（大黄蜂）和一个模仿者、传粉者和假定的寄生虫（食蚜虫）之间的生态和进化关系。其目的是预测未来物种分布变化对宿主-寄生虫关系的可能后果，同时为模仿的遗传起源提供罕见的见解。大黄蜂的幼虫寄生在各种大黄蜂的巢中。它们吃大黄蜂的孵化细胞、花粉储存和碎屑，但对宿主适应性的影响，因此寄生的程度，还没有被量化。成年苍蝇显示出惊人的颜色多态性，不同的个体类似于不同的大黄蜂物种。它们被认为是“贝叶斯”模仿者，愚弄捕食者，让他们认为美味无害的苍蝇是有严密防御的，不好吃的。在物种分布建模和基因组测序的时代，这个系统提供了独特的机会来解决两个迷人的研究问题。首先，全球环境变化将如何影响假定的寄生虫与其宿主之间的关系，当这些宿主也充当模仿的模型时？其次，哪些基因负责贝叶斯模仿，这些基因的选择如何受到群落组成变化的影响？这个项目将结合实验室实验和物种分布模型来解决这两个问题。

Global climate change, habitat loss and the impact of invasive species are major threats to economically and ecologically important pollinators, including bees and hoverflies. Shifts in species ranges, extinctions and colonization events will change community composition, with manifold effects on biodiversity and ecosystem services. Our ability to predict these effects is hampered by the complexity of natural ecosystems: species interact ecologically, and coevolve, such that species responses to environmental change cannot be estimated in isolation. In this project, we will explore the ecological and evolutionary relationships between a community of important pollinators (bumblebees) and a mimic, pollinator and putative parasite (the hoverfly Volucella bombylans), in the context of environmental change. The aim is to predict the likely consequences of future shifts in species distributions for the host-parasite relationship, whilst providing a rare insight into the genetic origins of mimicry. V. bombylans larvae infest the nests of various species of bumblebee (Bombus spp.). They eat bumblebee brood cells, pollen stores and detritus, but the impact on host fitness, and hence the degree of parasitism, has not been quantified. The adult flies display a striking colour polymorphism, with different individuals resembling different bumblebee species. They are assumed to be "Batesian" mimics, fooling predators into thinking that palatable and harmless flies are heavily-defended and unpalatable. In the era of species distribution modelling and genome sequencing, this system provides unique opportunities to address two fascinating research questions. Firstly, how will global environmental change affect the relationship between a putative parasite and its hosts, when those hosts also act as a model for mimicry? Secondly, which genes are responsible for Batesian mimicry, and how is selection on those genes influenced by variation in community composition? This project will address these two questions with a combination of laboratory experiments and species distribution modelling.