FIGURE 2. Post-reproductive mother presence (at the time that each offspring began to reproduce) and correlates of each offspring's (son and daughter) fitness and key life-history traits in Finland.
a–c, Offspring fitness; d–f, Key life-history traits. A living post-reproductive mother is associated with: a, increased lifetime fecundity of offspring (F1,607 = 9.44, P = 0.0022); b, increased lifetime reproductive success of offspring (LRS) (F1,593 = 8.23, P = 0.0043); c, increased numbers of grandchildren produced when post-reproductive mother was living in the same village versus elsewhere (F1,293 = 3.98, P = 0.047); d, reduced ages at first reproduction of offspring (F1,814 = 52.65, P < 0.0001); e, reduced first three inter-birth intervals (F1,977 = 6.45, P = 0.011), but not those thereafter (F1,711 = 0.84, P = 0.36); and f, increased survival of grandchildren until age 15 (log-rank test: 22 = 19.78, P < 0.0001). Panels a–e show predicted means (1 s.e.) from GLMMs after controlling for effects of offspring socio-economic status, geographic and temporal differences in living conditions, birth order, sex, number of siblings, mother's age and repeated measures of mother, where appropriate. Panel f shows Kaplan–Meier survival curves for grandchildren depending on the age and presence of a post-reproductive grandmother.