Parental age can have considerable effects on offspring phenotypes and health. However, intergenerational effects may also have longer-term effects on offspring fitness. Few studies have investigated parental age effects on offspring fitness in natural populations while also testing for sex- and environment-specific effects. Further, longitudinal parental age effects may be masked by population-level processes such as the selective disappearance of poor-quality individuals. Here, we used multi-generational data collected on individually marked Seychelles warblers (Acrocephalus sechellensis) to investigate the impact of maternal and paternal age on offspring lifespan and lifetime reproductive success. We found negative effects of maternal age on female offspring lifespan and lifetime reproductive success, which were driven by within-mother effects. There was no difference in annual reproductive output of females born to older versus younger mothers, suggesting that the differences in offspring lifetime reproductive success were driven by effects on offspring lifespan. In contrast, there was no association between paternal age and female offspring lifespan or either maternal or paternal age and male offspring lifespan. Lifetime reproductive success, but not annual reproductive success, of male offspring increased with maternal age, but this was driven by between-mother effects. No paternal age effects were found on female offspring's lifetime reproductive success but there was a positive between-father effect on male offspring's lifetime reproductive success. We did not find strong evidence for environment-dependent parental age effects. Our study provides evidence for parental age effects on the lifetime fitness of offspring and shows that such effects can be sex-dependent. These results add to the growing literature indicating the importance of intergenerational effects on long-term offspring performance and highlight that these effects can be an important driver of variation in longevity and fitness in the wild.

These datasets are related to the manuscript (accepted for publication in Evolution Letters):

Sex-dependent effects of parental age on offspring fitness in a cooperatively breeding bird

A. M. Sparks, M. Hammers, J. Komdeur, T. Burke, D. S. Richardson, H. L. Dugdale

Please see the README files for descriptions of the columns in the datasets. Full details of the methods can be found in the journal article. 

R scripts for analyses can be found at https://github.com/Seychelle-Warbler-Project/Sparks_2022_EvolLett

These datasets were collected as part of the long-term individual-based study of Seychelles warblers on Cousin Island in the Seychelles.

For questions related specifically to these datasets please contact Alexandra Sparks or Hannah Dugdale