Grandmaternal age at reproduction affects grandoffspring body condition, reproduction and survival in a wild population of lizards

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.