Mechanisms of fitness optimization.

<p>The impact of pre-breeding maternal feeding treatment (a: <i>ad libitum</i>–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.