Models of aging predict that sperm function and fertility should decline with age as sperm are exposed to free radical damage and mutation accumulation. However, theory also suggests that mating with older males should be beneficial for females because survival to old age is a demonstration of a male’s high genetic and/or phenotypic quality. Consequently, declines in sperm fitness may be offset by indirect fitness benefits exhibited in offspring. While numerous studies have investigated age-based declines in male fertility, none has taken the integrated approach of studying age-based effects on both male fertility and offspring fitness. Here, using a cohort-based longitudinal study of zebrafish (Danio rerio), we report a decline in male mating success and fertility with male age but also compensating indirect benefits. Using in vitro fertilisation, we show that offspring from older males exhibit superior early survival compared to those from their youngest counterparts. These findings suggest that the high offspring fitness observed for the subset of males that survive to an old age (~51 % in this study) may represent compensating benefits for declining fertility with age, thus challenging widely held views about the fitness costs of mating with older males.

READMEThis file explains all of the variables in each of the datasets that accompany: Johnson et al. 2017 ms. Evidence that fertility trades off with early offspring fitness as males ageMale survival dataData for adult male survival analysisMaleSurvival.csvMating success dataData for adult male mating success analysisMatingSuccess.csvSperm production dataData for sperm production analysisSpermProduction.csvSperm concentration dataData for sperm concentration analysisSpermConcentration.csvCASA dataData for sperm velocity and motility analysesCASA.csvIVF dataDataset for offspring early development and hatching analysisIVF.csvProgeny survival dataDataset for progeny survival analysisProgenySurvival.csvCASA_CS dataDataset for sperm trait analysis (cross-sectional)CASA_CS.csvIVF_CS dataDataset for offspring early development and hatching analysis (cross-sectional)IVF_CS.csvProgenySurvival_CS dataDataset for progeny survival analysis (cross-sectional)ProgenySurvival_CS.csv