Meeting Abstract
The environment an individual experiences during development can have formative effects on physiology and as a result, impacts how energy is partitioned to key life history activities such as reproduction. Metabolic hormones, including insulin-like growth factor (IGF)-1, play a fundamental role determining how energy is allocated within the body and therefore are likely responsible for mediating these individual differences in pace of life. IGF-1 is responsive to diet and influences growth, reproduction and survival and therefore, may be an important mechanism by which the early environment impacts reproductive performance. We manipulated dietary protein intake in wild house mice (Mus musculus). Parents were maintained on a 10% low (L) or a 20% high protein diet (H). The F1 offspring were then kept on the same diet or switched to the alternative diet at weaning, creating four treatment groups (HH, HL, LH, and LL). We predicted mice with the greatest reproductive effort (RE) would exhibit the greatest plasma IGF-1 concentrations. We observed no difference in RE among treatment groups. We measured plasma concentrations of IGF-1 in mice at weaning and at 1 year. At weaning, IGF-1 hormone concentrations similar between treatment groups (P=0.35). At one year and having the opportunity to mate for 8 months, mice in the HL treatment group had significantly greater concentrations of IGF-1 compared to the LH treatment group (p=0.04). Interestingly, circulating levels of IGF-1 were negatively correlated with reproductive effort (p=0.02). The results of this study suggest that RE is not influenced by maternal diet; however IGF-1 may still be important in matching RE to the current dietary conditions.
