Data from: Senescence impacts reproduction and maternal investment in bottlenose dolphins

Reproductive senescence is evident across many mammalian species. An
emerging perspective considers components of reproductive senescence as
evolutionarily distinct phenomena: fertility senescence and
maternal-effect senescence. While fertility senescence is regarded as the
aging of reproductive physiology, maternal-effect senescence pertains to
the declining capacity to provision and rear surviving offspring due to
age. Both contribute to reproductive failure in utero making it difficult
to differentiate between the two prenatally in the wild. We investigated
both components in a long-lived mammal with prolonged maternal care
through three parameters: calf survival, interbirth interval (IBI), and
lactation period. We provide clear evidence for reproductive senescence in
a wild population of bottlenose dolphins (Tursiops aduncus) using 34+
years of longitudinal data on 229 adult females and 562 calves. Calf
survival decreased with maternal age, and calves with older mothers had
lower survival than predicted by birth order, suggesting maternal-effect
senescence. Both lactation period and IBIs increased with maternal age,
and IBIs increased regardless of calf mortality, indicating interactions
between fertility and maternal-effect senescence. Of calves that survived
to weaning, last-born calves weaned later than earlier-born calves,
evidence of terminal investment, a mitigating strategy given reduced
reproductive value caused by either components of reproductive senescence.