Exploring senescence across the tree of life

Senescence, the increasing risk of mortality and decline in reproduction with age after achieving maturity, is an evolutionary paradox. How can a process detrimental to the fundamental pillars of fitness evolve under the guise of natural selection? Many theories have sought to explain this counterintuitive phenomenon. Generally, the weakening of the strength of natural selection with age is the most supported answer. Recently, however, explosions of demographic data and critical re-analyses of established theory have revealed that patterns of senescence across the tree of life are variable, and that the strength of selection may not always weaken with age. Together, these lines of evidence suggest that our understanding of the processes that drive the evolution of, and escape from, senescence, is far from complete. This doctoral thesis will explore untapped avenues of research born out of these developments. Its ultimate goal is to extend the theoretical framework of senescence to better incorporate previously unconsidered factors likely to be driving these empirically observed patterns, with a particular focus on sociality. I propose to use a combination of theoretical, comparative, and experimental methodology to tackle why some but not all species senesce.

BBSRC Priority Areas
Understanding the diversity of ageing patterns across the tree of life is essential to humanity's battle to extend our own health and lifespans. My doctoral thesis will, therefore, address the "Healthy ageing across the lifecourse" research priority for the BBSRC. In addition, I will compile and work with large data sets of demographic information, thus contributing to the BBSRC's "Data driven biology" remit.