Spatial ecology of a range‐expanding bumble bee pollinator. Issue 3 (8th January 2019)

• Record Type: Journal Article
• Authors: Crowther, Liam P.; Wright, David J.; Richardson, David S.; Carvell, Claire; Bourke, Andrew F. G.
• Is Part Of: Ecology and evolution. Volume 9:Issue 3(2019)
• Page Start: 986
• Page End: 997
• Publication Date: 2019-01-08
• Subjects: colonization -- foraging distance -- genetic structure -- invasive species -- microsatellite -- population biology; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.4722
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Molecular methods have greatly increased our understanding of the previously cryptic spatial ecology of bumble bees ( Bombus spp.), with knowledge of the spatial ecology of these bees being central to conserving their essential pollination services. Bombus hypnorum, the Tree Bumble Bee, is unusual in that it has recently rapidly expanded its range, having colonized much of the UK mainland since 2001. However, the spatial ecology of B. hypnorum has not previously been investigated. To address this issue, and to investigate whether specific features of the spatial ecology of B. hypnorum are associated with its rapid range expansion, we used 14 microsatellite markers to estimate worker foraging distance, nest density, between‐year lineage survival rate and isolation by distance in a representative UK B. hypnorum population. After assigning workers to colonies based on full or half sibship, we estimated the mean colony‐specific worker foraging distance as 103.6 m, considerably less than values reported from most other bumble bee populations. Estimated nest density was notably high (2.56 and 0.72 colonies ha −1 in 2014 and 2015, respectively), estimated between‐year lineage survival rate was 0.07, and there was no evidence of fine‐scale isolation by distance. In addition, genotyping stored sperm dissected from sampled queens confirmed polyandry in this population (mean minimum mating frequency of 1.7 males per queen). Overall, our findings establish critical spatial ecological parameters and the mating system of this unusual bumble bee population and suggest that short worker foraging distances and high nest densities are associated with its rapid range expansion. Abstract : Unlike many other bumble bee populations, Bombus hypnorum in the United Kingdom has been unequivocally successful, having rapidly expanded its range in recent years. We predict that this range, and hence demographic, expansion is associated with worker foraging over dense resources at a short range. We used neutral genetic markers to assign workers collected from a site in the core of B. hypnorum's new UK range, to reveal a mean colony‐specific worker foraging distance of just 104 m—among the shortest range foraging documented for any Bombus population.