Parental age at reproduction influences offspring size and survival by affecting pre- and postnatal conditions in a wide variety of species, including humans. However, most investigations into this manifestation of ageing focus upon maternal age effects; the effects of paternal age and interactions between maternal and paternal age are often neglected. Furthermore, even when maternal age effects are studied, pre- and postnatal effects are often confounded. Using a cross-fostered experimental design, we investigated the joint effects of prenatal paternal and maternal and postnatal maternal ages on five traits related to offspring outcomes in a laboratory population of a species of burying beetle, Nicrophorus vespilloides. We found a significant positive effect of the age of the egg producer on larval survival to dispersal. We found more statistical evidence for interaction effects, which acted on larval survival and egg length. Both interaction effects were negative and involved the age of the egg-producer, indicating that age-related prenatal maternal improvements were mitigated by increasing age in fathers and foster mothers. These results agree with an early study that found little evidence for maternal senescence, but it emphasizes that parental age interactions may be an important contributor to ageing patterns. We discuss how the peculiar life history of this species may promote selection to resist the evolution of parental age effects, and how this might have influenced our ability to detect senescence.

The data was obtained from a cross-fostering experiment involving young (11-18 days) or old (52-65 days post eclosion) males and females. Males provided only pre-natal care, whereas females could provide pre- and post-natal care. 

The traits studied were:

Egg length and width

Larval weight at dispersal

Foster mother weight change

Larval survival to dispersal.

Univariate and bivariate models were run in ASREML 4.1