Age at reproduction can influence the survival and future reproduction of an individual as well as that of their offspring. Remarkably, it has been shown that grandmaternal age at reproduction can also affect the characteristics of grandoffspring in humans and in laboratory or semi-captive animals. However, currently we do not know whether grandmaternal age effects exist in wild populations.

We gathered data on female age at reproduction, offspring and grandoffspring characteristics using a 16-year long-term survey of a natural population of the common lizard, Zootoca vivipara. The dataset contains 579 grandoffspring from 135 litters.

Body size at birth was not correlated with grandmaternal age at reproduction. However, grandoffspring body condition at birth, grandoffspring survival and reproductive performance of granddaughters were dependent on grandmaternal age. These relationships were independent of maternal age.

An age-structured model showed that the global effect of grandmaternal age was nonlinear and was largely driven by its effect on grandoffspring survival. Fitness was higher for granddaughters produced by grandmothers of intermediate ages.

The study shows that age can shape life-history traits for more than one generation, documenting the importance that grandmaternal age can have in wild populations.

The data were obtained from a mark-recapture survey of common lizards (Zootoca vivipara) conducted each year from 1989 through 2004 in a natural population at Mont-Lozère (1420 m a.s.l., 44°23’03’’N, 3°52’40’’E, Cévennes National Park, southeastern France). Pregnant females are captured each year and kept in the laboratory for three-four weeks until parturition. At birth, offspring are measured (snout-vent length, to the nearest mm), weighed (to the nearest mg), sexed and marked by toe-clipping. This protocol allows us to determine the maternal lineages, the age at reproduction, litter size, litter success, offspring body size and body mass at birth, and offspring sex. Lizards that are not born in the laboratory can be aged if they are captured in the field as juveniles or subadults, and this allows us to age many grandmothers. Offspring are recaptured at the end of the reproductive season (in September, i.e. before hibernation) and the summer of the next years (in June-July) to estimate their survival. Litters do not always result in live offspring, they can contain stillborns, unfertilised eggs or abortive embryos. We defined litter size as the total litter size, and litter success as the proportion of live offspring in a litter.