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1. MEASURE FOR MEASURE: FEMALE REPRODUCTIVE PLASTICITY

Individuals that respond to their social and sexual environments gain substantial fitness benefits. Males of many species can detect cues that indicate they are at increased risk of sperm competition. Responses include competing more strongly for matings, mating for longer and transferring more ejaculate components and / or sperm.   However, little is known about the consequences for females of responding directly to the intra- or inter-sexual competitive environment. Nor is it known what are the consequences of indirect responses by females of mating with responding / non-responding males. Females are expected to gain benefits from responding adaptively to cues that indicate the likelihood of remating, potential cost of each mating, expected ‘per mating’ investment. These responses are expected to include effects on future generations via the transmission of ‘competition’ information to offspring in a form that allows adaptive responses by one or both sexes.   The fitness outcomes of plastic interactions of both mating partners has been subject to limited theory, but as yet no empirical study. Plasticity expressed by either one or both parties is expected to maximise fitness when there is no sexual conflict. Our prediction, under conflict, is that the fitness benefit for the plasticity-expressing sex is diminished when their partner is also plastic.   Using the well-characterised genetics of the fruitfly model system and powerful genetic isoline resources we are conducting a NERC-funded project to conduct hypothesis-driven tests of the significance of the expression of socio-sexual plasticity in females.


2. FUNCTIONAL SIGNIFICANCE AND REGULATION OF THE REPRODUCTIVE 'TRANSFEROME'.

Funded by the BBSRC, our focus in this recent project is on a group of vitally important semen proteins transferred along with sperm - the 'transferome'. It has been realized for many decades seminal fluid proteins are far more than a simple sperm buffer. In fact they can cause profoundly important effects on female behaviour and physiology. These effects have been best studied in the fruitfly but similar effects are also seen across a huge variety of animal taxa including in humans.

In the fruitfly there are about 130 semen proteins making up the transferome. They result in a huge variety of vitally important effects: they cause females to lay more eggs, to eat more (and of different types of foods), to be less sexually receptive to males, to switch on immune genes, to retain more sperm in storage, to show altered patterns of water balance and to sleep less.

Despite the importance of the transferome to both males and females and its high degree of flexibility, we know little about how it is regulated. In this project we investigate the control and regulation of this complex and important system. We hypothesise that an effective way to regulate 130 individual components of the transferome is to manage them in 'sets' controlled by regulatory hubs.

3. ALL'S FAIR WHEN LOVE IS WAR: THE EVOLUTION OF LIFESPAN AND AGEING UNDER SEXUAL CONFLICT.

It has long been realised that the interactions between the sexes over reproduction are often characterized by conflict rather than co-operation. Hence the sexes often 'disagree' about how much energy and resources to invest in reproduction and how often to make that investment.

A good example is evolutionary disagreements over how often to mate. Males often gain from mating frequently and females often do not. Furthermore, females often suffer significantly reduced lifespan from mating too frequently (an effect that is also seen in humans).

These sexual interactions may underlie an important and long-standing puzzle: why it is that males and females often have very different longevity. For example, women generally live at least 4 years longer than men.

The central aim of this research project, funded by the NERC, is to (i) evaluate whether sexual conflict underlies lifespan differences between males and females and (ii) identify the underlying genes that are responsible.

4. COLONISATION, DOMESTICATION AND POPULATION CONTROL IN PEST INSECTS

Safeguarding world food supplies is a grand challenge. It is therefore of great importance to develop safe, environmentally friendly and effective new techniques for tackling pests of agriculturally important crops.

Existing methods based on the release of mass reared insects have been applied with some great successes. However, one potentially significant hurdle remains. To release large numbers, pest insects are domesticated and mass reared in laboratory facilities. This inevitably selects for individuals that are highly successful in the laboratory, rather than in the field. It is increasingly clear that a significant contribution to health comes from associations with gut bacteria and changes to gut bacteria are an important component of laboratory adaptation.

We aim to understand how hosts and their gut bacteria adapt to laboratory mass rearing conditions. With this knowledge, undesirable effects of such adaptation can be slowed or reversed. The main objective, funded by the BBSRC, is to use the medfly (an agricultural pest of world-wide importance) to document changes in life history, gut bacteria, and their interaction, upon colonization to the laboratory and the ability to achieve population suppression.