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

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.