ABSTRACT
Challenging or adverse early-life conditions, even when transient, can have long-lasting effects on individual phenotypes and reduce lifespan across species. If these effects can be mitigated, even in part, by a high quality later-life environment, then differences in future resource access may explain variation in vulnerability and resilience to early-life adversity. Using 32 years of data on 886 wild North American red squirrels, we test the hypothesis that the negative effects of early-life adversity on lifespan can be mitigated by later-life food abundance. We first define early-life adversities as factors that significantly reduce the likelihood of juvenile survival, and find that they had cumulative negative effects on lifespan. We then show that although experimental supplementation with additional food increases individual lifespan, it did not change the consequences of early-life adversity on longevity. A naturally-occurring future food boom experienced in the second year of life, however, did eliminate the longevity costs of a harsh early-life environment. Together, our results demonstrate that adverse conditions experienced early in life reduce lifespan in red squirrels and thus may influence patterns of natural selection beyond juvenile viability. That these effects can be mitigated by a high-quality future environment suggests a non-deterministic role for early-life conditions on later-life phenotypes, and highlights the importance of evaluating the impact of early-life conditions in the context of an animal’s entire life course.
Competing Interest Statement
The authors have declared no competing interest.
