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RESEARCH PRODUCT

Senescence and longevity : from physiological mechanisms to evolutionary processes : studies in birds and mammals

subject

description

There is an incredible diversity of lifespan in the animal kingdom ranging from a few days for small gastrotrichs worms to several hundred of years for some bivalves or tortoises. This amazing diversity has long questioned biology researchers. The growing interest in the phenomenon of aging, mainly due to the increase in life expectancy in humans, has questioned researchers on processes that determine patterns of longevity and ageing. On the one hand, biomedical and biogerontological studies helped describe numerous cellular and physiological mechanisms related to aging. Among these mechanisms, oxidative stress has been identified as playing a major role, through life-time accumulation of damage generated by production of metabolic free radicals. On the other hand, the development of evolutionary theories of aging has contributed to understanding ultimate origins of ageing and of the diversity of life history traits. However, these approaches, although complementary, have long remained separated and works that integrate physiological mechanisms such as oxidative stress in an evolutionary perspective have known only recent developments. In this thesis, we studied how mechanisms such as oxidative stress and its associated costs produced during reproduction or immune response could play a role in the evolution of patterns of ageing in birds and mammals by (i) studying the role of antioxidants as key resources involved in adaptive trade-offs between reproduction and survival through age, (ii) studying the long-term effects of the early environment, (iii) studying the relationship between inflammatory response and contrasted patterns of ageing and longevity between birds and mammals, (iv) focusing particularly on immune regulatory mechanisms, emphasizing their crucial role in fitness of hosts, especially late in life. Overall, our results highlight the importance of physiological constraints in terms of key resources limitation (i.e. antioxidants) or damage caused during costly and destructive activities and on intra-and inter-specific patterns of ageing.