Final Report Summary - PARENTAL AGE EFFECTS (Epigenetic transgenerational Effects of Parental Age on Fitness)
Reproducing at old age is known to incur costs such as an increased risk of polysomy, higher infant and maternal mortality ect. One often-overlooked cost of late reproduction could come from transgenerationally inherited effects of old age on the lifespan or fertility of the next generation. Such transgenerational, epigenetic effects are likely important for our understanding of the evolution of costs of late reproduction if the effect is reliably inherited by future generations. Such an effect was first described by Alexander Graham Bell. The negative influence of parental age on offspring fitness has been observed in many taxa in the laboratory (coined the “Lansing effect”), and also in humans. However, it has never been shown in the wild, likely because studying transgenerational effects of age on the fitness of offspring requires an exact knowledge of parental age and of the fate of offspring – data that are difficult to gather in natural populations. Here we demonstrate in a natural, pedigreed population of house sparrows that parental ages have a negative effect on lifetime reproductive fitness. In a long-term cross-fostering experiment, we demonstrate that this transgenerational Lansing effect is not environmentally induced, but matrilineally inherited. Our study reveals hidden consequences of late-life reproduction that unexpectedly persist into the second generation, which potentially affects the evolution of ageing and lifespan. (Schroeder et al. 2015, PNAS).