Data from: Evidence that fertility trades off with early offspring fitness as males age

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.