Fig 1.
Schematic diagram of the experimental setup.
The hypothesized effect of the pre-breeding feeding treatment of the female (ad libitum–AL, food restriction–FR) on the optimization of her parental investment during lactation. Considering the changes that may occur with time, we investigated this effect over the course of five equal lactation periods.
Table 1.
Definition of the Fixed Effects Tested in the Analyses of (a) Birth Litter Size, (b) Weaning Litter Size, (c) Maternal Weight Change, (d) Offspring Weight Change, and (e) Probability of Offspring Death.
Fig 2.
Litter size at birth and at weaning.
The effect of pre-breeding maternal feeding treatment (ad libitum–AL; food restriction–FR) on litter size (a) at birth and (b) at weaning in the families with and without litter reduction. Bars indicate LS-means ± S.E.; numbers above the bars indicate the sample size (*P < 0.05, **P < 0.01).
Table 2.
Final GLMM Models with Factors that Affected Birth Litter Size and Weaning Litter Size.
Fig 3.
The effect of pre-breeding maternal feeding treatment (ad libitum–AL; food restriction–FR) on total litter reduction (proportion of all offspring deaths from day 1 to 21); numbers above the bars indicate the sample size (*P < 0.05).
Fig 4.
Dynamics of offspring mortality.
The effect of pre-breeding maternal feeding treatment (ad libitum–AL; food restriction–FR) on the proportions of offspring deaths in particular lactation periods; numbers above the bars indicate the sample size (*P < 0.05).
Fig 5.
The effect of pre-breeding maternal feeding treatment (ad libitum–AL; food restriction–FR) on the relationships between maternal weight change and (a) prior litter size, (b) offspring weight change, and (c) litter biomass change. Only the regression lines of the significant relationships are shown.
Table 3.
Final GLMM Model with Factors that Affected Maternal Weight Change.
Fig 6.
The effect of pre-breeding maternal feeding treatment (ad libitum–AL; food restriction–FR) on the relationships between offspring weight change and (a) prior litter size, (b) maternal weight change, and (c) litter biomass change. Only the regression lines of the significant relationships are shown.
Table 4.
Final GLMM Model with Factors that Affected Offspring Weight Change.
Fig 7.
Probability of offspring death.
The effect of pre-breeding maternal feeding treatment (ad libitum–AL; food restriction–FR) on the relationships between the probability of offspring death and (a) prior litter size, (b) mother’s prior weight, (c) maternal weight change, and (d) offspring prior weight. Only the regression lines of the significant relationships are shown.
Fig 8.
Interaction of maternal weight change with offspring weight.
The probability of offspring death depending on the interaction between the maternal weight change and offspring prior weight (a) in the ad libitum (AL)-fed mothers, and (b) in the food-restricted (FR) mothers.
Table 5.
Final GzLMM Model with Factors that Affected Probability of Offspring Death.
Fig 9.
Mechanisms of fitness optimization.
The impact of pre-breeding maternal feeding treatment (a: ad libitum–AL; b: food restriction–FR) on the relationships between maternal condition (mother’s prior weight, maternal weight change), offspring condition (offspring prior weight, offspring weight change), and offspring mortality (probability of offspring death, litter biomass change). The arrows indicate the directions of the significant effects of particular relationships. Positive and negative relationships are respectively denoted with + and–. The scheme demonstrates that: (1) offspring condition was only positively associated with maternal condition in the AL-fed mice; (2) maternal condition was only positively associated with offspring condition in the FR mice; and (3) offspring mortality decreased with increasing maternal and offspring condition in both groups, but only in the AL-fed mice did their condition decline with increasing offspring mortality.