What drives aggression? Linking Ecology, Evolution, and Genes

Overview

Social interactions are some of the most dramatic, complex, and varied behaviours on Earth. From colourful courtship displays to brutal dominance disputes, behaviours between individuals of the same species have captured the public and scientific imagination. Social behaviours can shape the survival and reproductive success of individuals, as well as determine group size, habitat selection, and predator avoidance. Unlike many morphological traits, behaviours are flexible and context-dependent, allowing organisms to respond rapidly to changing environments, yet their expression and potential for change are also shaped by deep evolutionary constraints—such as phylogenetic history, genetic architecture, and trade-offs with other fitness-related traits. Studying behavioural diversity therefore allows us to investigate how ecological pressures can generate adaptive plastic traits over evolutionary time.

One of the biggest obstacles organisms face in their struggle for survival is members of their own species. Within a species, competition between members of the same sex is almost ubiquitous throughout the animal kingdom, with winners gaining mates, more food, and often producing more offspring. However, competition has costs, such as injury or death, suggesting individuals need to choose carefully when to be aggressive. Most research has focused on male-male aggression and has neglected female-female aggression.

Theories of sexual selection developed to explain male competition have led to a proliferation of theories and sub-disciplines which have greatly improved our understanding of biological diversity. However, few (if any) theories exist specifically for female competition. It is becoming increasingly clear that females fight in many taxa, with important consequences for survival and reproductive success. Female aggression varies greatly within and among species, ranging from minimal to even exceeding male aggression. Male and female competition should arise under fundamentally different ecological drivers — females primarily in response to resource limitation, males for access to fertilisation — and these differences should predict when, over what, and how aggression evolves across species.

This project will use Drosophila (fruit flies) as a powerful comparative system to investigate how ecological factors and evolutionary history shape the expression and regulation of aggression. The student will examine aggression across 10-15 Drosophila species that vary in their natural history, including differences in mating systems, reproductive strategies, resource use, and oviposition ecology. By combining comparative analyses with controlled behavioural experiments, the project will test how ecological drivers influence the evolution of aggressive behaviour.

To complement behavioural and ecological data, the student will apply transcriptomic approaches across species, and within selected species under experimental conditions, to identify patterns of gene expression associated with aggression. Candidate genes revealed by these analyses may then be functionally tested using established molecular genetic tools. This integrative approach will link ecological drivers, behavioural expression, and molecular mechanisms to provide a comprehensive picture of the evolution of aggression.

Methodology

This project will use a variety of lab-based methods. First, there will be insect husbandry techniques – acquiring and maintaining stock lines of multiple Drosophila species. Next, there will be behavioural assays (e.g. mating and aggression assays), which will be recorded and stored on a computer. The student will then learn machine learning skills to train the computer to automatically track and score behaviour on these videos. They will also learn key transcriptomic skills – extracting RNA, performing techniques to prepare samples for sequencing and bioinformatics for analysing transcriptomic data. Other skills include reproductive assays, taking morphological measurements (using microscopes, microbalances), and data analysis of behavioural and morphological data using R.

Training and Skills

The student will receive training in key skills in behavioural ecology, evolutionary biology, and bioinformatics. The student will learn insect husbandry and handling skills, behavioural assaying, using machine learning to track animals and score complex social behaviours. They will also learn transcriptomic lab-based skills and desk-based bioinformatics and data analysis skills. They will also acquire comparative analysis skills, general lab skills (such as microscope use). The student will be encouraged to go to relevant workshops to acquire such skills (e.g. transcriptomics workshop).

Funding Notes

The funding for this project is in place. Success will depend on the quality of the applications relative to competing applications. If you are interested in applying, in the first instance contact the supervisor Dr Ellie Bath (eleanor.bath@durham.ac.uk), with a CV and covering letter, detailing your reasons for applying for the project, by no later than 12th January 2027.