Evolution of aging when the environment varies in time and space.

Summary This thesis is part of the broad field of research on the evolution of life history traits. Life history traits are directly involved in the reproduction and survival, and thus the selective value, of organisms. Interest in life history traits is motivated by the immense diversity of these traits in the living world. In particular, there is a great diversity of aging patterns in nature. This thesis addresses the evolution of aging in natural populations. As with most life history traits, theoretical research on the evolution of aging has been conducted in the context of a single, stable population living in a constant environment. The goal of this thesis is to predict how aging evolves when populations are structured in space and when the environment varies in time and space. My approach has been mainly theoretical, but I have been able to explore some questions with data collected in natural populations. In the introduction, I present the necessary elements to consider when looking at the evolution of life history traits in age-structured populations. I make the observation that these populations are subject to environmental variations and structured in space. In the first part, I show that environmental variations, in time and space, can affect senescence patterns. I use quantitative genetic methods where I hypothesize that mutations have an environment and age specific effect. In the second part, I focus on the consequences of extinction-recolonization dynamics on the resource sharing strategy between survival and reproduction of individuals according to their age. In particular, I show that dispersal is a source of variability for this strategy and examine how dispersers and non-dispersersers differ in their life history traits in 3 data sets. Overall, my results show that taking into account the complex ecological and environmental conditions in which organisms live provides insight into the diversity of aging patterns in nature. Finally, I give a short review of this thesis and then give possible perspectives to my research and more generally to research on the evolution of aging.