Intergenerational effects of climate generate cohort variation in lizard reproductive performance.

An evaluation of the link between climate and population dynamics requires understanding of climate effects both within and across generations. In ectothermic vertebrates, demographic responses to climate changes should crucially depend on balancing needs for heat and water. Here, we studied how temperature and rainfall regimes experienced before and during adulthood influenced reproductive performances (litter size, offspring size, and survival) in a natural population of the live-bearing common lizard, Lacerta vivipara, monitored continuously from 1989 to 2004. Rainfall regime, but not temperature, had both immediate and delayed effects on these reproductive performances. Rainfall during the first month of life was positively correlated with juvenile survival. Females experiencing more rainfall during gestation produced smaller neonates that showed greater survival when controlling for the positive effect of body size on survival. Furthermore, females that experienced heavier rainfall when in utero produced fewer but longer neonates during adulthood. These demographic effects of rainfall on adult reproductive traits may come from maternal effects of climate conditions and/or from delayed effects of rainfall on the environment experienced early in life. Irrespective of the precise mechanism, however, this study provides evidence of intergenerational climate effects in natural populations of an ectothermic vertebrate.