Long-term fitness effects of the early-life environment in a wild bird population

Environmental conditions and experiences during development can have
long-term fitness consequences, including a reduction of adulthood
survival and reproduction. These long-term fitness consequences may play
an important role in shaping the evolution of life history. We tested two
hypotheses on the long-term fitness effects of the developmental
environment – the silver spoon hypothesis and the internal Predictive
Adaptive Response (PAR) hypothesis. We compared the change in annual
survival and annual reproductive output with age for adult birds hatched
and reared in poor (impacted by anthropogenic noise, and/or high sibling
competition) and good (not impacted by anthropogenic noise, and/or low
sibling competition) environments. We used a 23-year longitudinal fitness
dataset from a wild house sparrow (Passer domesticus) population that was
unusually precise due to the isolation of the population. We used a
cross-fostering setup to disentangle postnatal environmental effects from
prenatal effects. We found that adults that experienced more within-brood
competition had a stronger increase in early-life annual survival, but
also a stronger decrease in late-life annual survival. Females that
hatched in a noisy environment produced fewer genetic recruits annually,
supporting a sex-specific silver spoon effect. Males reared in a noisy
environment had accelerated reproductive schedules, presenting a
sex-specific internal PAR. Our results highlight that anthropogenic noise
can have long-term fitness consequences in wild animals, altering their
life-history strategies, and that there may be sex-specific effects.