Meeting Abstract

52.2  Thursday, Jan. 6  Dietary calcium, maternal skeletal condition and lifetime reproductive performance of white-footed mice (Peromyscus leucopus) BOOHER SCHMIDT, C.M.*; HOOD, W.R.; Auburn University, Alabama; Auburn University, Alabama cmb0011@auburn.edu

To maximize lifetime reproductive success, females must balance investment in current reproduction with the potential impact of that investment on her body condition. Several mammalian species experience bone loss during reproduction that results from mobilizing skeletal calcium stores to meet demands of offspring production. Decreased bone volume is related to increased fracture risk, which may impair survival or future reproductive efforts, and the extent that bone is lost can be exacerbated when calcium intake is low. Thus, dietary calcium availability may drive a trade-off between maternal skeletal condition and reproductive performance, ultimately affecting lifetime reproductive success. We tested this by providing female white-footed mice (Peromyscus leucopus) with either a low-calcium or a standard diet and 4-5 breeding opportunities, and assessing both their reproductive performance and maternal skeletal condition over the course of their lives. We characterized reproductive performance of each female by mean litter size, sex ratio, pup size and mass, pup growth rate, and number of litters and individual offspring produced. Maternal bone characteristics, including bone volume, were measured using micro-computed tomography. Sex ratio of pups produced by mothers on the low-calcium diet was skewed towards females, and these pups gained proportionally less mass over time than those from mothers on the standard diet. Mothers on the low-calcium diet exhibited a reduction in bone volume relative to those on the standard diet. Thus, it appears calcium availability influences both a reproductive female’s skeletal condition and maternal investment strategies with regard to offspring sex.