Bumblebee foraging patterns: plant-pollinator network dynamics and robustness

Abstract

Pollination is a vital ecosystem service that supports and maintains ecosystems globally. Additionally, pollination has high economic value to humans and is essential for our global food production requirements. Recent threats to pollination services and declines in insect pollinators have galvanised a large and varied body of research with the aim of protecting pollination services. One approach, adopted in this thesis, is to examine plant-pollinator communities using network theory; enabling us to visualise, quantify and analyse communities as a whole. Network theory is increasingly used by ecologists; the study of ecological systems is ideal for a network approach. However, we identify a gap in our understanding and consideration of community dynamics when it comes to using plant-pollinator network data. In this thesis, our overarching goal is to better understand the dynamics of plant-pollinator communities over a range of time scales. We combine theoretical, observational and experimental techniques to examine how plant-pollinator networks change over time in terms of network structure and pollinator behaviour. We first examine the robustness of plant-pollinator networks to theoretical extinctions over evolutionary time. We then determine how much a plant-pollinator community changes over a pollination season, and over two years, through observations of flowering phenologies. Thirdly, we determine the impacts on network structure and pollinator behaviour of the experimental removal of a plant species from a plant-pollinator community, also focussing on bumblebee species to explore species level responses. Finally, we focus on the foraging patterns of bumblebee individuals to understand how foraging behaviour, on the timescales of sequential flower visits, can facilitate bumblebee species adapting to longer term changes in their foraging environment and ultimately how individual behaviour responds to and impacts the dynamics of the whole plant-pollinator community.

Date of Award	19 Jun 2019
Original language	English
Awarding Institution	University of Bath
Supervisor	Richard James (Supervisor) & Michael Pocock (Supervisor)