DOI: 10.5061/dryad.t76hdr7zv
title: No severe genetic bottleneck in a rapidly range-expanding bumblebee pollinator

description: Genetic bottlenecking can limit the success of populations colonising new
 ranges. However, successful colonisations can occur despite bottlenecking,
 a phenomenon known as the genetic paradox of invasion. Eusocial
 Hymenoptera such as bumblebees (Bombus spp.) should be particularly
 vulnerable to genetic bottlenecking, since homozygosity at the
 sex-determining locus leads to costly diploid male production. The Tree
 Bumblebee (B. hypnorum) has rapidly colonised the UK since 2001 and has
 been highlighted as exemplifying the genetic paradox of invasion. Using
 microsatellite genotyping, combined with the first genetic estimates of
 diploid male production in UK B. hypnorum, we tested two alternative
 genetic hypotheses (‘bottleneck’ and ‘gene flow’ hypotheses) for B.
 hypnorum’s colonisation of the UK. We found that the UK population has not
 undergone a recent severe genetic bottleneck and exhibits levels of
 genetic diversity falling between those of widespread and range-restricted
 Bombus species. Diploid males occurred in 15.4% of reared colonies,
 leading to an estimate of 21.5 alleles at the sex-determining locus.
 Overall, the findings show that this population is not bottlenecked,
 instead suggesting that it is experiencing continued gene flow from the
 continental European source population with only moderate loss of genetic
 diversity, and does not exemplify the genetic paradox of invasion.
description: Data collection was carried out following the Methods section in
 Brock <em>et al.</em> No severe genetic bottleneck in a
 rapidly range-expanding bumblebee pollinator.
description: <strong>Bottleneck analysis</strong>
 The bottleneck analyses were carried out using worker
 microsatellite genotyping data from Crowther <em>et
 al. </em>(2019) and Dreier <em>et al. </em>(2014).
 Analysis code and full details of how to perform the bottleneck
 analyses can be found here. <strong>References</strong> Crowther, L.P., Wright, D.J., Richardson, D.S., Carvell, C. and Bourke, A.F., 2019. Data from: "Spatial ecology of a range-expanding bumble bee pollinator". https://figshare.com/articles/Data_from_Spatial_ecology_of_a_range-expanding_bumble_bee_pollinator_/7284803. Dreier, S., Redhead, J.W., Warren, I.A., Bourke, A.F., Heard, M.S., Jordan, W.C., Sumner, S., Wang, J. and Carvell, C., 2014. Microsatellite genotype data for five species of bumblebee across an agricultural landscape in Buckinghamshire, UK. NERC Environmental Information Data Centre. (Dataset). https://doi.org/10.5285/6a408415-0575-49c6-af69-b568e343266d.   <strong>Diploid male analysis</strong>  The diploid male analysis was carried out using male microsatellite genotyping data found in this Dryad directory. Analysis code and full details of how to perform the diploid male analysis analyses can be found here. This Dryad directory contains two data files (.csv format) and two read me files (.docx format): <strong>File:</strong> <em>Raw_male_typing_matrix.csv</em> <strong>Description: </strong>Raw genotypes across 14 microsatellite markers from initial genotyping and regenotyping reactions for all sampled males used in this study. Full details can be found in the respective <em>Raw_male_typing_matrix_README.docx</em> file. <strong>File:</strong> <em>Consensus_male_genotypes.csv</em> <strong>Description:</strong> Consensus genotypes across 14 microsatellite markers for all sampled males used in this study. Full details can be found in the respective <em>Consensus_male_genotypes_README.docx</em> file.