Food, Sex and Death: Costs of Reproduction and the Mechanistic Basis of Ageing in the field cricket Teleogryllus commodus

Rates of senescence and average lifespan vary greatly within and between animal species, yet two clear patterns have emerged. 1) females in most species tend to live much longer than males and senesce at a slower rate and 2) caloric restriction (CR) extends lifespan and improves health in a range of species. One process that can potentially unite these patterns is the production of reactive oxygen species (ROS), which are highly reactive molecules that damage a range of other molecules and cellular structures. Since oxidative damage increases with age, senescence results from the damage generated by accumulating ROS levels. The primary source of damage occurs when ROS leak from the mitochondria during cellular metabolism. Thus, the typically higher metabolic rate (and ROS production) of males may explain their increased rate of senescence and reduced longevity relative to females. Moreover, because mitochondrial function is more efficient with lower amounts of energy, CR may extend lifespan by reducing ROS leakage. Our proposed research will examine the effect of CR on sex differences in reproductive effort, cellular damage by ROS and rates of ageing in the native Australian field cricket, Teleogryllus commodus. We will conduct fieldwork in Australia on six geographically isolated wild cricket populations to examine the relationship between reproductive effort, oxidative stress and ageing in the sexes. We already have compelling evidence that these populations differ genetically in how quickly they age and their reproductive effort and that these variables negatively related in both sexes. We then build on this field study by conducting controlled feeding experiments in the laboratory, using specialised diets that differ in caloric content but not nutrition, to examine how CR influences the relationship between reproductive effort, oxidative stress and ageing. Finally, we will supplement a standardized diet with antioxidants (vitamin A & E, carotenoids) to determine if these molecules are able reduce cellular damage by ROS and therefore rates of ageing.