Mechanisms of sexual and aggressive social behaviour

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Stalk eyed flies fighting

In many animals males and females frequently encounter individuals of the same and opposite sex in social groups. In order to maximise the benefits and minimise the costs of these encounters, males and females should rapidly adjust their behaviour in response to information about the individuals in their social group. Often we know little about the mechanisms used to achieve this behavioural plasticity – a problem our lab addresses.

In many species sex-specific behaviour is characterised by competition between individuals of the same sex (e.g. males fighting each other for access to females, or females fighting each other for access to food) and choice over mates of the opposite sex (e.g. male courtship and female selectivity). But competitors and potential mates vary in many respects – their health, relatedness, familiarity, fertility etc. – so individuals should use all the available information to determine how best to respond to others. We use Drosophila and stalk eyed flies to determine how and why males and females behave differentially to potential competitors and mates.

When mating occurs, males transfer much more to females than just sperm cells. The seminal fluid contains a cocktail of proteins that can have dramatic effects on both male and female reproductive success. Some of these proteins evolve extremely rapidly, whilst others are highly evolutionarily conserved: but few are functionally characterised, despite their importance in fertility and health. Our lab investigates the role of these proteins, with a focus on sexual selection and life-history evolution.

In Drosophila, as in many species, the male seminal fluid proteins are essential for fertility, and cause a profound remodelling of female physiology and behaviour: for example, they can increase female fecundity, reduce female receptivity and modulate female lifespan. We investigate how males allocate seminal proteins to females, how these proteins influence the fate of male sperm and the rate of female ageing, and to what extent the seminal proteome changes with age and the social environment.