Abstracts (first author)
Actuarial senescence increases the risk of extinction of mammal populations
Despite recent general acknowledgement that senescence has significant negative demographic manifestations in natural environments across a wide range of animal species, we still do not know if it can significantly impact the dynamics and viability of wild populations. Focusing on actuarial senescence (i.e., the decline of survival probabilities at old ages), we use specific demographic information to project the dynamics and extinction risk of wild populations of 58 species of mammals in the presence or absence of senescence. Our projections reveal major negative effects of ageing on population dynamics and viability, with a 27% decrease of the time to extinction on average and a potential deterioration of the species projected conservation status in 10% of the cases. The magnitude of the senescence cost is relatively homogenous among mammal orders at the exception of primates, which are disproportionally affected, due to their slow pace of life. Senescence is associated with particularly strong increases of the extinction risk in species with high annual survival probabilities of young adults and long intervals between litters, independently of their place in the phylogeny, indicating that the pace of life history can be used to forecast the detrimental effects of ageing on the viability of species.