Energy Allocation in Mammalian Reproduction

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 considered gestation 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 to gestation 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.

Opportunistic mothers: female marmosets (Callithrix kuhlii) reduce their investment in offspring when they have to, and when they can

“…This care is energetically costly for females. Lactation is the most energetically expensive component of reproduction for female mammals (see review in Gittleman and Thompson, 1988), and callitrichid females have been observed to lose weight (cotton-top tamarins: Sánchez et al, 1999) and significantly increase their energetic intake (cotton-top tamarins: Kirkwood and Underwood, 1984;saddle-back tamarins: Goldizen, 1987) during lactation. Carrying callitrichid infants comes at a 21% increase in the caloric cost (per minute) of traveling (Tardif, 1996).…”

Use of space by the Neotropical caviomorph rodent Thrichomys apereoides (Rodentia: Echimyidae)

“…data), indicate that T. apereoides reproduce mainly during the dry season. If this is indeed the reproductive pattern, presumably then smaller DHRs in the dry season, as well as other parameters, might be a consequence of female reproductive activities, because more energy would need to be allocated to reproduction (mating, feeding and care of pups) (GITTLEMAN & THOMPSON 1988), at the expense of energy expended in movements. Therefore, it is expected that there is some relationship Table I.…”

“…It was observed that for species that reproduce in a time of lower food availability, females may show a pattern of smaller displacement. In mammals, the greater parental investment lies with the females (TRIVERS 1972, GITTLEMAN & THOMPSON 1988; therefore, the females tend to conserve energy expended in movement, establishing lower home ranges (LORETTO & VIEIRA 2005). In Panamá, for the spiny rat Proechimys semispinosus (Tomes, 1860), ENDRIES & ADLER (2005) observed that individuals of both the sexes had larger home ranges during the rainy season.…”

“…A number of life history factors have been used to explain this variation among individuals including age, sex, season, breeding season, and population density (MAGNUSSON et al 1995, KELT & VAN VUREN 2001, ENDRIES & ADLER 2005. It has also been shown that the spacing pattern is associated with the social mating system used (ADLER 2011, MAHER & BURGER 2011, with the dispersion in the environment of individuals being strongly influenced by the way they behave in accordance to their needs and their role in their particular mating system (CLUTTON-BROCK & HARVEY 1978, GITTLEMAN & THOMPSON 1988.…”

Elevated urinary testosterone excretion and decreased maternal caregiving effort in marmosets when conception occurs during the period of infant dependence

“…During this phase of development, females nurse their infants every few hours (common marmoset: Missler et al, 1992) and, along with other group members, carry infants more than 90% of the time (common marmoset; cottontop tamarin; golden lion tamarin, Leontopithecus rosalia; saddle-back tamarin, S. fuscicollis; silvery marmoset, C. argentata; see review in Tardif et al, 1998). This care is energetically costly for females; lactation is the most energetically expensive component of reproduction for female mammals (see review in Gittleman and Thompson, 1988), and infant carrying comes at a 21% increase in the caloric cost of traveling (Tardif, 1996). We operationally defined conception APID as conception occurring 4 weeks following birth, and later.…”