23 October 2012, 16:15
Ernst-Abbe-Platz 2, conference room 3319

Revisiting the evolution of aging: repair is the optimal unicellular strategy

Robert Clegg (Centre for Systems Biology, School of Biosciences, University of Birmingham, UK)

As part of the continuing debate over the role of replicative senescence (i.e. the life strategy leading to aged parents and rejuvenated offspring) in unicellular organisms, we revisit the evolutionary origin of aging with an established individual-based model of the autocatalytic growth of each cell’s biomass. Previous models have either implemented growth as being inhibited by undamaged biomass or have not embedded accumulation of damage in a growing cell. They suggest that damage segregation, rather than repair, leads to the highest population growth rate in a constant environment. In contrast, we find that repair is the best strategy (above minimal rates of damage) even though we make repair costly both in rate and efficiency. If damage is toxic, repair combined with damage segregation can be the winning strategy if investment into repair is fixed, and so not optimal. These results hold in a dynamic environment where strategies compete for resources. We identify which assumptions made in previous models are critical and suggest that testing dependence on model assumptions should be part of the modeling process. We conclude that optimal investment in repair is the most competitive strategy, at least for unicellular organisms.