Energy Allocation in Mammalian Reproduction

TLDR

Mammalian reproduction comprises a continuous sequence of events—mating, gestation, parturition, lactation, post‑lactational care, and recovery—whose relative energy allocation is difficult to compare across species due to life‑history variability, allometry, phylogeny, and individual differences. The authors review empirical and theoretical studies on energy use across these reproductive stages, examining measurement methods, broad consumption patterns in diverse mammals, and identifying costly characteristics such as birthing and parental care that lack energetic data. They conclude that future research should integrate energetic measurements into behavioral studies and incorporate behavioral compensation mechanisms into physiological investigations to achieve more complete analyses. SYNOPSIS.

Abstract

SYNOPSIS. On behavioral, hormonal, and physiological grounds, mammalian reproduction can be compartmentalized into the following continuous sequence of events: mating (courtship, estrous), gestation, parturition, lactation, post-lactational parental care, and maternal recovery. We point out that comparing the relative allocation of energy for these events across mammals is difficult because of life history variability (e.g., litter size, birth weight), allometry, phylogeny, and individual variation. We review the empirical and theoretical literature on each of these events with respect to: different methodologies in measuring energy use;broad patterns of energy consumption across diverse mammalian taxa; and, identification of particular reproductive characteristics (e.g., birthing, parental care) which may be costly but have yet to receive energetic measurements. Although most studies have consideredgestation and lactation the critical reproductive events for energy expenditure, variation in these events is substantial and almost certainly is a function of relative allocation of time togestation vs. lactation as well as the presumed energetic costs of mating, birthing and parental care. In addition, repeated observations show that behavioral compensation is an extremely important strategy for minimizing energy requirements during reproduction. From this review, we argue that more complete analyses will come from (1) incorporating energetic measurements in studies of mammalian behavior and (2) including mechanisms of behavioral compensation into physiological studies.