Evolutionary conflict over animal nutrition and diet choice

Recent advances in animal nutrition research have produced remarkable findings. Across many species, it is not only the amount of food eaten but also the protein and carbohydrate content of that food that influences health. In particular, diets that are relatively high in protein and low in carbohydrate diets enhance reproduction, whereas low protein and high carbohydrate diets prolong life. These results often lead to a picture of an ideal diet composition that maximizes a species' reproduction and another diet composition that maximizes lifespan, a result of keen interest for human health.

However, our current understanding of the ideal diet is limited to overly simplified laboratory conditions. This is a problem because the diet compositions that maximize reproduction and lifespan in benign and stable conditions might not translate to the complex environments that all organisms, including humans, experience in the real world. In particular, an animal's mating frequency might strongly affect its nutritional needs, because increased mating frequency is associated with increased reproduction and lifespan in many species. We currently know little about how nutritional preferences and optima shift in response to mating, or about how individuals can achieve their dietary optima despite conflicts of interest over nutrition with their mates and family members.

The goal of my research is to address this gap by bringing an evolutionary perspective to nutritional ecology. I aim to discover how the diets that maximize health, lifespan and reproduction vary with the ecological and social settings that animals experience. I will use the fruit fly Drosophila melanogaster, an experimentally tractable animal that shares most of its nutritional physiology with vertebrates - including humans - to enable me to directly test nutritional hypotheses in experiments that are not feasible with human subjects. With this research I will focus on three questions: how diets that maximize lifespan and reproduction change with mating frequency; to what extent evolutionary conflicts of interest - for example, when mothers have different optimal diets from their offspring - shapes dietary preferences; and by what mechanisms might males influence the nutritional preferences of their mates. This work has the potential to contribute to our basic understanding of animal adaptation and to the potential for improving the health, lifespan or reproductive capacity of humans and other animals.

My research will examine nutrition, reproduction, and lifespan, in the context of the mating environment. This is basic science with the long-term potential to contribute to UK quality of life, and economic development through the agri-food, livestock and companion-animal nutrition industries.

Who will benefit from this research?
I have identified three groups who will potentially benefit from my research.
- Managers who design diets for agricultural species, companion animals and species of conservation interest
- Managers who contribute to the nutritional content of diets of human populations
- The UK public

How will they benefit from this research?

Managers in the agri-food, companion animal food, and conservation sectors who design animal diets may benefit from my results. They may be better able to fine-tune diets that support long lifespan and health depending on the sex and mating environment of their animals. The metabolomic component of my research will be of relevance for this purpose and might aid in translating my results to vertebrate species.

Managers in the agri-food industry who influence the nutritional content of human diets in the UK industrial may benefit from my results. They may help the industry produce food that supports health in the UK population (e.g., through balanced macronutrient content) without increasing resource inputs. This is the case even though my results are based on studies in fruit flies, because fruit flies and other animals, including humans, share the same basic metabolic and nutrient processing pathways.

Finally, my work will be of interest to the UK public. Members of the public will benefit from learning about the relationship between behaviour and nutrition. In the long term, this may support individual diet choices for health and well-being throughout life. Members of the public also have a keen interest in health- and nutrition-related research, as well as research on breeding behaviour, as demonstrated by the great frequency of media reports covering studies in these areas. I expect that my results will therefore be of interest to the public, which will foster interest in and support for basic science and its potential applied value.