Abstract/Summary

Biodiversity is under immense pressure from a range of threats, including land-use change, pollution, overexploitation, and climate change. Climate change significantly impacts species’ ranges, physiology, and phenology (the timing of recurring biological events). Species-specific responses to climate change may alter the synchrony of inter-species interactions, potentially affecting the provision of important ecosystem services such as pollination. This thesis explores the impact of climate change on wild bees (including many important pollinator species) and their interaction with economically important pome and stone fruits. Focussing on Great Britain, it assesses historic patterns and predicts potential future spatio-temporal trends in fruit, wild bees, and the synchrony between them. Analysis of apple blossom and wild bee pollinator phenology revealed different patterns of change over time, although both emerged earlier in warmer years. Many wild bee species are advancing their emergence dates in response to temperature, however shifts were species-specific. The climate envelopes of many British wild bee species were predicted to shift poleward under future climate scenarios. The ability of a species to fill its climate envelope was found to be influenced by its life-history traits, specifically foraging behaviour, body size, and overwintering strategy. Finally, an important spatial data gap in fruit tree phenology recording was uncovered. Consequently, this thesis developed a citizen science project, FruitWatch, to collect blossom dates of fruit trees across Great Britain. Blossom predictions based on these records showed a strong link to temperature, with earliest dates predicted in the warmest locations. These results have direct implications for fruit growers, showing changing spatio-temporal dynamics of fruit crops and wild bee pollinators. Understanding these shifts is crucial to maintaining effective pollination of orchards. More broadly, this thesis provides a framework for assessing spatio-temporal shifts in many taxa, highlighting citizen science as a powerful tool for monitoring spatio-temporal shifts.