Project highlights

  • Your research will be high impact science geared towards the conservation of bumble bees – highly important pollinators of both wild flowers and important crops.
  • Your research will be relevant to the ~240 species of bumble bee world-wide and also to the 20% of all insects that have haplo-diploid sex determination.
  • You will gain invaluable skills in bioinformatics and the analysis of ‘big data’ from next generation sequencing, and present your research at national and international conferences.

Overview

Bumble bees are a diverse group of key pollinators that suffer from the negative impact of anthropogenic change. This results in declining and fragmented populations that impacts on the bees themselves and so on the wild flowers and crops that they pollinate [1,2]

Importantly, the genetics and life-history of bumble bees make these changes especially damaging [3].

The aim of this PhD research is to investigate two understudied and important genetic issues relevant to the persistence of bumble bee populations in changing environments.

Haplodiploidy.  Female bees (workers and queens) are diploid (maternal and paternal genome copies), whereas males are usually haploid (maternal copy only). An upshot is that natural selection potentially acts more effectively because genetic dominance is absent in genes expressed in males.  Compared to diplo-diploids (like us), theory predicts that mildly deleterious variants – potentially important for future adaptation to changing environments – are more efficiently removed by selection, whereas adaptive but recessive variation is more likely fixed by selection.

Sex determination.  Bumble bee sex is thought to be determined by a single genetic locus: the complimentary sex determination locus (CSD). Normally, heterozygotes develop as females, while hemizygotes (haploid) develop as males.  However, inbreeding or reduced genetic variation caused by declining populations leads to diploid homozygotes at CSD which develop as diploid males. Diploid males have an enormous impact on population fitness as they replace valuable workers.

Importantly, theory shows that diploid male production greatly increases the likelihood of population extinction [4].

Currently we have little empirical data on whether natural selection is more efficacious in haplodiploid species or on the level of genetic variation at the CSD locus. The aim of this PhD is to help fill this knowledge gap.

Questions to answer include:

  • Are there lower levels of potentially deleterious genetic variation:
    1. in bumble bees compared to diploid insects?
    2. in male expressed genes compared to female expressed genes within bumble bees?
  • What genetic variation is at CSD in bumble bees?
  • Does decreased genetic variation at CSD correlate with population extinction?

Host

University of Leicester

Theme

  • Organisms and Ecosystems

Supervisors

Project investigator

  • Dr Rob Hammond, Genetics and Genome Biology, University of Leicester.  Email: [email protected]

Co-investigators

  • Dr Eamonn Mallon, Genetics and Genome Biology, University of Leicester.

How to apply

Methodology

The project will use a combination of genomic analysis coupled with fieldwork (bee collection) and laboratory crosses.

Principal methods will be:

  • Bee husbandry (crosses to produce diploid males)
  • Molecular biology (DNA extraction, DNA sequencing)
  • High throughput massively parallel genome sequencing.
  • Bioinformatics (Linux environment, shell scripting, Python programming, use of R for statistics).
  • Quantitative analysis of genetic variation.

Training and skills

Bioinformatics skills are essential in ‘big data’ modern biology, especially evolutionary and environmental biology. You will gain highly transferable skills in: biological computing and programming (e.g. bash scripting, Python, R), handling next generation sequencing data in a Linux environment, transcriptome assembly, molecular evolutionary analysis, manuscript preparation and giving presentations.

In addition to CENTA training you will receive tailored training from:

  • Supervisors directly (e.g. population genetics theory, bioinformatics)
  • University of Leicester courses (e.g. R, Python)

Partners and collaboration

Hammond and Mallon have worked on bumble bees and have a track record of collaborating together and co supervising PhD students [e.g. 5, 6].  Mallon has expertise in bumble bee biology and husbandry, genomics and statistical analysis, Hammond brings expertise in genomics, population genetics and social insect biology.

Further details

Please contact Dr Rob Hammond, University of Leicester.

Email: [email protected]

Phone: 0116 252 5302

Website: https://www2.le.ac.uk/departments/genetics/people/hammond

To apply to this project please visit: https://le.ac.uk/study/research-degrees/funded-opportunities/centa-phd-studentships

Possible timeline

Year 1

Familiarisation with the literature, sample collection, bee husbandry, DNA extraction, genome sequencing. Bioinformatics skills development using already collected cDNA data.

Year 2

Analysis of bumble bee crosses, bioinformatics analysis of sequencing data. Conference poster presentation

Year 3

Bioinformatic analysis of sequencing data Manuscript preparation / thesis preparation. Presentation of results at international conference.

Further reading

  1. Gallai N., Salles J.M., Settele J., Vaissière B.E. 2009 Economic valuation of the vulnerability of world agriculture confronted with pollinator decline. Ecological Economics 68(3), 810-821. (doi:10.1016/j.ecolecon.2008.06.014).
  2. Potts S.G., Biesmeijer J.C., Kremen C., Neumann P., Schweiger O., Kunin W.E. 2010 Global pollinator declines: trends, impacts and drivers. Trends Ecol Evol 25(6), 345-353. (doi:10.1016/j.tree.2010.01.007).
  3. Chapman R.E., Bourke A.F.G. 2001 The influence of sociality on the conservation biology of social insects. Ecol Lett 4(6), 650-662. (doi:10.1046/j.1461-0248.2001.00253.x).
  4. Zayed A., Packer L. 2005 Complementary sex determination substantially increases extinction proneness of haplodiploid populations. Proc Natl Acad Sci U S A 102(30), 10742-10746. (doi:10.1073/pnas.0502271102).
  5. Price J., Harrison M.C., Hammond R.L., Adams S., Gutierrez-Marcos J.F., Mallon E.B. (2018) Alternative splicing associated with phenotypic plasticity in the bumble bee Bombus terrestrisMolecular Ecology 27(4), 1036-1043 (doi:10.1111/mec.14495).
  6. Harrison M.C., HammondR.H., Mallon, E.B (2015) Reproductive workers show queen-like gene expression in an intermediately eusocial insect, the buff-tailed bumble bee Bombus terrestris. Molecular Ecology 24(12), 3043-3063. (doi:10.1111/mec.13215).

 

COVID-19

This PhD project is resilient to all but the most severe impacts (e.g. total shutdown of travel & university).  Collection of wild bees involves outdoor fieldwork within the UK where likelihood of infection is low.  Furthermore, for lab crosses colonies will be purchased from commercial producers so fieldwork is not necessary for this element. In the event of a total shutdown the project could focus more on: 1) using publicly available genome data to test hypotheses, 2) developing theoretical models investigating the impact of diploid males under varying colony sizes and life histories (in collaboration).