Diversity of ageing across the tree of life

Abstract

Evolution drives and is driven by demography. A genotype moulds its phenotype’s age-patterns of mortality and fertility in an environment; these two patterns in turn determine the genotype’s fitness in that environment. Hence, to understand the evolution of ageing, age-patterns of mortality and reproduction need to be compared for species across the tree of life. Yet few studies have done so and only for a limited range of taxa. Here we contrast standardised age patterns for 11 mammals, 12 other vertebrates, 10 invertebrates, 12 vascular plants, and a green alga. While it has been predicted that evolution should inevitably lead to increasing mortality and declining fertility with age after maturity, these species exhibit extraordinary variety, including increasing, constant, decreasing, humped and bowed trajectories for both long and short lived species. This diversity challenges theoreticians to develop broader perspectives on the evolution of ageing and empiricists to study the demography of more species.