Age at first reproduction and senescence in Eastern chipmunks (Tamia striatus)

Senescence is the degradation of biological functions with increasing age. Its existence and relationship with life-history strategies remains poorly studied in short-lived wild vertebrate species. We investigated the relationships between age at first reproduction (AFR), reproductive senescence and longevity in an eastern chipmunk (Tamias striatus) population, where the first opportunity to breed is conditioned by pulses of seed production by trees (i.e., masts). We used 11 years of data from a longitudinal study, in which females breed for the first time at seven, 15, or 22 months of age and males at seven or 15 months of age. We first assessed the effect of age on three traits associated with breeding performance, namely the number of offspring produced, and the probability of weaning or siring a litter. We then tested whether an earlier AFR accelerated reproductive senescence and reduced survival of both males and females. We found sex-specific relationships between AFR and senescen...