Fig. 1.

Four ways in which the death of a female primate mother (M) may be linked to her offspring’s fitness (F₁), if the death of M occurs while F₁ is still dependent on M. First, F₁ should display reduced survival during the immature period, following the death of M (especially before weaning but also after), because F₁ will lack the critically important social, nutritional, and/or protective resources that M provided (blue arrow). Second, F₁ should display reduced survival in the period before M actually dies, because, on average, mothers are in worse condition shortly before their death compared to mothers that survive the same period. We therefore expect M to provide lower-quality maternal care to F₁ during the weeks to years immediately preceding M’s death (purple arrow). Third, if F₁ survives these first two challenges, she is likely to be in chronically worse condition during adulthood because of reductions in maternal allocation that she received during development (red arrow). F₁ should therefore face reduced survival in adulthood, years (or even decades) after the death of M occurred. Fourth, this chronic reduction in F₁’s condition may have an intergenerational effect, such that F₂ (F₁’s offspring) also experience reduced immature survival (gold arrow). The blue and red arrows have been previously tested in several species; the analyses presented here focus on the purple and gold arrows.