Maternal reproductive senescence shapes the fitness consequences of the parental age difference in ruffed lemurs

Abstract

In humans, pronounced age differences between parents have deleterious fitness consequences. In particular, the number of children is lower when mothers are much older than fathers. However, previous analyses failed to disentangle the influence of differential parental age from a direct age effect of each parent. In this study, we analyse the fitness consequences of both parental age and parental age differences on litter size and offspring survival in two closely related species of lemurs living in captivity. As captive lemurs do not choose their reproductive partner, we were able to measure litter size and offspring survival across breeding pairs showing a wide range of parental age differences. However, we demonstrated that the effect of the parental age difference on litter size was fully accounted for by female reproductive senescence because females mating with much younger males were old females. On the other hand, both parental age difference and female reproductive senescence influenced offspring survival. Our results emphasize the importance of teasing apart the effect of parental reproductive senescence when investigating the health and fitness consequences of parental age differences and also provide new insights for conservation programmes of endangered species.

Reproductive senescence and parental effects in an indeterminate grower

“…the so‐called Lansing effect) have focused on maternal age (Lemaître & Gaillard, 2017) whereas old paternal age should also negatively influence offspring performance (Lemaître & Gaillard, 2017) as a result of decreasing sperm quality with increasing paternal age (Johnson & Gemmell, 2012). Studies looking at the effect of both maternal and paternal ages as well as their potential interactions are now strongly required (Dzyuba, 2006; Tidière et al., 2018).…”

Sex‐specific actuarial and reproductive senescence in zoo‐housed tiger (Panthera tigris): The importance of sub‐species for conservation

“…Actuarial senescence has been shown to differ between sexes according to species mating system (e.g., in ungulates, Tidière et al, 2015): as a polygynous species (Horev et al, 2012), we expected that tiger males exhibit a faster actuarial senescence than females, resulting in a shorter longevity. In addition, age is a widely proposed factor to explain reproductive success variability in zoo-housed as well as free-ranging populations (Augustus et al, 2006;Hayward et al, 2014Hayward et al, , 2015Karniski et al, 2018;Tidière et al, 2018). Accordingly, as only females bear gestation and offspring care costs until cubs disperse (Sunquist & Sunquist, 2002), we expected more marked reproductive senescence patterns for females than for males.…”

“…Including an interactive effect of parental ages allowed us to test for the possible effects of the age-difference between parents on breeding success (e.g., Tidière et al, 2018). Effects of parental ages at litter birth was tested for four types of age-specific models:…”

Lifespan decreases with proportion of sons in males but not females of zoo‐housed tigers and lemurs

“…Black‐and‐white ruffed lemurs and red ruffed lemurs were analysed together in this study, because the species have similar life histories (e.g. body mass, Kappeler, 1991), survival and reproductive patterns (Tidière et al., 2017, 2018) and housing practices (Whipple, 2016). Similarly, the six tiger sub‐species (Liu et al., 2018) were analysed together.…”