Lead supervisor: Rebecca Kilner, Zoology
Co-supervisor: Walter Federle, Zoology
Brief summary:
This project will determine how the sexes divide up the various duties of care when they cooperate to raise young together, and investigate whether task specialisation by each sex causes the evolution of sexual dimorphism
Importance of the area of research concerned:
Sexual dimorphism is conventionally thought to be the result of competition within each sex: for mates, or for resources, or for social dominance.
This project will consider a novel alternative: can sexual dimorphism also result from instances of cooperation (where cooperation is defined as behaviour that has evolved to promote the fitness of conspecifics as well as the actor itself)? Theoretical analyses suggest that cooperation is more likely to be evolutionarily stable when there is division of labour among cooperating individuals. Each member of the team then becomes a task specialist – and dependent on other team members for the effective completion of other essential activities. Specialisation might then select for a specific morphology or physiology, for the more effective completion of the task at hand. You will focus on parental care as a form of cooperation.
Project summary :
Do divergent selection pressures also operate on the sexes during biparental care, due to the way in which the different tasks of parental care are divided between males and females when they work together to raise offspring?
You will test this idea with state of the art imaging, biomechanical, behavioural and evolutionary experiments, and investigate its broader significance with comparisons among natural populations of the same species, and comparisons across species using Museum samples. You will focus on the burying beetle Nicrophorus vespilloides in which the sexes are almost identical, except for the size of their heads: males have wider heads than females.
What will the student do?:
You will describe the extent of head size dimorphism in wild populations of burying beetles to investigate the extent to which it varies. You will then use state of the art imaging and biomechanical analyses (in collaboration with Dr David Labonte at Imperial College, London and Prof Walter Federle at Cambridge) to link form to function. In addition, you will carry out experiments in the lab that measure the strength and direction of selection on head size during parental care tasks carried out typically by males versus females – to test whether selection acts in the same way, or differently, on head size during each form of care. Finally, you investigate whether the head size dimorphism is typical of Nicrophorus beetles in general, and Silphids more broadly.
References - references should provide further reading about the project:
Shine, R. 1989 Ecological causes for the evolution of sexual dimorphism: a review of the evidence. Quarterly Review of Biology vol. 64 pp 419-461 doi/10.1086/416458
Scott, M. P. 1998 The ecology and evolution of burying beetles. Annual Review of Entomology vol. 43 pp 595-618 doi/abs/10.1146/annurev.ento.43.1.595
Jarrett, B. J. M. et al. 2022 Multilevel selection leads to divergent coadaptation of care-giving parents during pre-hatching parental care. BioRxiv 2022.05.23.493134
Applying
You can find out about applying for this project on the Department of Zoology page.