Ageing and Physical Performance in Wild Crickets

Abstract

Aging and longevity variation have been a hot topic for researchers for many decades. Despite the great number of studies on senescence and longevity, both the causes and the mechanisms of aging remain a subject of debate. Though it can be difficult to study senescence traits in the wild this is seen as vital to understanding the evolution of senescence especially as theory suggests it is so closely related to experienced levels of extrinsic mortality. In this thesis, I use a long-term observation study which utilises 24 hour observational video to capture the lives of a population of field crickets (Gryllus campestris) throughout their adult lives. This provides the opportunity to ask a number of questions around the theme of senescence and lifespan. The first section aims to find whether senescence is seen in a trait directly affecting rate of predation and if sex biased predation rates alter this. The second section examines lifespan and the causes of the variation we see within species. My research identifies no senesce or sex biased aging in this wild population. I found that there was selective disappearance of faster individuals in early life. I saw no effect of speed performance on the lifespan of these crickets, but there were trade-offs between various activity measures and lifespan. My work adds to current understanding of how variation in aging rates and life-history traits are maintained under natural selection. My findings underline the fact that this complex subject requires further testing in the natural environment.