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Title: The Tree Bumblebee, Bombus hypnorum : ecology and genetics of a naturally colonising pollinator
Author: Crowther, Liam
ISNI:       0000 0004 7654 0118
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2017
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Bumblebees are essential pollinators but, worldwide, many species are declining. The Tree Bumblebee, Bombus hypnorum, is a notable exception in that, having been first recorded in the UK (in southern England) in 2001, it has since rapidly spread to become common in much of England, Wales and Scotland. In this thesis I therefore investigated the ecology and genetics of B. hypnorum in the UK to better understand the factors underlying ecological success in bumblebees as a whole. In Chapter 2, I used biological recorder data to model and estimate B. hypnorum's dispersal kernel. I found evidence for leptokurtic dispersal, with most queens dispersing a relatively short distance (mean, 4.3 km) but a few dispersing much further (e.g. 1% dispersing up to 23.9 km). In Chapter 3, I used a panel of neutral genetic markers (microsatellites) to investigate the demographic history of a representative UK B. hypnorum population. I found no evidence for a recent population bottleneck, suggesting that, rather than being the product of a single, chance event, B. hypnorum's colonisation of the UK may be better explained by continuous migration from continental Europe. In Chapter 4, I used the same marker set to reconstruct the colony membership of workers sampled from a landscape in two successive years and to estimate the mating frequency of queens. This revealed notably short colony-specific worker foraging distances (mean, 103.6 m), high, variable nesting densities and a mean frequency of 1.7 matings per queen. In Chapter 5, I investigated the foraging ecology of B. hypnorum in the field and found that an absolute advantage in efficient flower handling and not low flower constancy ('generalism') may be contributing to its ecological success. Overall, these results greatly increase our understanding of the mechanisms by which bumblebees achieve ecological success and hence should help inform their conservation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available