1.Age-related variation in reproductive performance is ubiquitous in wild vertebrate populations and has important consequences for population and evolutionary dynamics. 2.The ageing trajectory is shaped by both within-individual processes, such as improvement and senescence, and by the among-individual effects of selective appearance and disappearance. To date, few studies have compared the role of these different drivers among species or populations. 3.In this study, we use nearly 40 years of longitudinal monitoring data to contrast the within- and among-individual processes contributing to the reproductive ageing patterns in three albatross species (two biennial and one annual breeder), and test whether these can be explained by differences in life-histories. 4.Early life performance in all species increased with age, and was predominantly influenced by within-individual improvements. However, reproductive senescence was detected in only two of the species. In the species exhibiting senescent declines, we also detected a terminal improvement in breeding success. This is suggestive of a trade-off between reproduction and survival, which was supported by evidence of selective disappearance of good breeders. 5.We demonstrate that comparisons of closely-related species which differ in specific aspects of their life-history can shed light on the ecological and evolutionary forces shaping variation in ageing patterns.

MeanAnnualBSData used to calculate mean annual breeding success for each species (Figure S1)FailureStageNest outcomes, used to calculate proportion of failures that occurred during incubation vs chick rearing for each speciesAFRALRData used to calculate mean age at first and last reproduction for each sex and species (Table 1)BreedingSucAgeData for the population-level analysis, used to model age-related variation in breeding success for each sex and species (Figure 2; Table S1; Table S2)BreedingSucAgeBothSexesData for the population-level analysis where the age of both parents was known, used to compare the explanatory power of male and female age for each species (Table S3)EarlyAdulthoodData for the analysis of factors underpinning breeding success in early adulthood for each sex and species (controlling for selective appearance) (Table 2a; Table S4)LateAdulthoodData for the analysis of factors underpinning breeding success in late adulthood for each sex and species (controlling for selective disappearance) (Table 2b; Table S5; Table S6; Table S7)GENERAL STATEMENT PLEASE READ THIS BEFORE USING THE DATADATA DESCRIPTION