Ageing and senescence across reproductive traits and survival in superb fairy-wrens (Malurus cyaneus)

Why do senescence rates of fitness-related traits often vary dramatically? By considering the full ageing trajectories of multiple traits we can better understand how a species’ life-history shapes the evolution of senescence within a population. Here, we examined age-related changes in sex-specific survival, reproduction, and several components of reproduction using a long-term study of a cooperatively-breeding songbird, the superb fairy-wren (Malurus cyaneus). We compared ageing patterns between traits by estimating standardized rates of maturation, the age of onset of senescence, and rates of senescence, while controlling for confounding factors reflecting individual variability in life-history. We found striking differences in ageing and senescence patterns between survival and reproduction, as well as between reproductive traits. In both sexes, survival started to decline from maturity onwards. In contrast, all reproductive traits showed improvements into early
adulthood, and many...