Developmental Thermoenergetics of the Dasyurid Marsupial, Antechinus Stuartii

Westman, Wendy; Körtner, Gerhard; Geiser, Fritz

doi:10.1644/1545-1542(2002)083<0081:dtotdm>2.0.co;2

Cited by 13 publications

(9 citation statements)

References 33 publications

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“…Studies in the wild using doubly-labeled water have shown that female brown antechinuses metabolise about 30% more energy each day than they eat at this stage, so as in brush-tailed possums [15], antechinuses must deplete body reserves for milk production [28]. As in Westman et al [29], mothers in our study continued to grow until mid-lactation, then lost weight between days 65 and 110. Females in their first breeding season nearly doubled in body mass, so that they caught up with females in their second season in the middle of the lactation period (when young were 60–70 days old).…”

Section: Discussionsupporting

confidence: 62%

“…Brown antechinuses have eight teats (although occasional individuals have 9), and each young weighs 12–15 g at weaning, so a typical litter can weigh around 100 g at weaning, when the mother weighs around 20 g [27] . To feed this large mass of dependent offspring, mothers in the wild have a negative energy balance late in lactation; they deplete fat reserves to support milk production, and unlike non-breeding females at the same time of year, mothers lose a substantial amount of weight in the month before weaning [28] , [29] . Supplementary feeding experiments and population studies have shown that food available to mothers before and during lactation has a strong effect on juvenile survival and growth [30] , [31] .…”

Section: Methodsmentioning

confidence: 99%

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Costs of Reproduction and Terminal Investment by Females in a Semelparous Marsupial

Fisher

Blomberg

2011

PLoS ONE

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Evolutionary explanations for life history diversity are based on the idea of costs of reproduction, particularly on the concept of a trade-off between age-specific reproduction and parental survival, and between expenditure on current and future offspring. Such trade-offs are often difficult to detect in population studies of wild mammals. Terminal investment theory predicts that reproductive effort by older parents should increase, because individual offspring become more valuable to parents as the conflict between current versus potential future offspring declines with age. In order to demonstrate this phenomenon in females, there must be an increase in maternal expenditure on offspring with age, imposing a fitness cost on the mother. Clear evidence of both the expenditure and fitness cost components has rarely been found. In this study, we quantify costs of reproduction throughout the lifespan of female antechinuses. Antechinuses are nocturnal, insectivorous, forest-dwelling small (20–40 g) marsupials, which nest in tree hollows. They have a single synchronized mating season of around three weeks, which occurs on predictable dates each year in a population. Females produce only one litter per year. Unlike almost all other mammals, all males, and in the smaller species, most females are semelparous. We show that increased allocation to current reproduction reduces maternal survival, and that offspring growth and survival in the first breeding season is traded-off with performance of the second litter in iteroparous females. In iteroparous females, increased allocation to second litters is associated with severe weight loss in late lactation and post-lactation death of mothers, but increased offspring growth in late lactation and survival to weaning. These findings are consistent with terminal investment. Iteroparity did not increase lifetime reproductive success, indicating that terminal investment in the first breeding season at the expense of maternal survival (i.e. semelparity) is likely to be advantageous for females.

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Section: Discussionsupporting

confidence: 62%

Section: Methodsmentioning

confidence: 99%

Costs of Reproduction and Terminal Investment by Females in a Semelparous Marsupial

Fisher

Blomberg

2011

PLoS ONE

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“…Since the values that we obtained either from CO 2 and O 2 measurements gave similar FAS values, the only way this could have happened is because of too short metabolic trials (three hours). However, we imitated previous studies where typical duration of BMR records was 2–3 hours of duration (e.g., McNab, 2000; Westman et al, 2002; Polymeropoulos et al, 2012). …”

Section: Discussionmentioning

confidence: 99%

Aerobic power, huddling and the efficiency of torpor in the South American marsupial, Dromiciops gliroides

et al. 2012

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SummaryDuring periods of cold, small endotherms depend on a continuous supply of food and energy to maintain euthermic body temperature (Tb), which can be challenging if food is limited. In these conditions, energy-saving strategies are critical to reduce the energetic requirements for survival. Mammals from temperate regions show a wide arrange of such strategies, including torpor and huddling. Here we provide a quantitative description of thermoregulatory capacities and energy-saving strategies in Dromiciops gliroides, a Microbiotherid marsupial inhabiting temperate rain forests. Unlike many mammals from temperate regions, preliminary studies have suggested that this species has low capacity for control and regulation of body temperature, but there is still an incomplete picture of its bioenergetics. In order to more fully understand the physiological capacities of this “living fossil”, we measured its scope of aerobic power and the interaction between huddling and torpor. Specifically, we evaluated: (1) the relation between basal (BMR) and maximum metabolic rate (MMR), and (2) the role of huddling on the characteristics of torpor at different temperatures. We found that BMR and MMR were above the expected values for marsupials and the factorial aerobic scope (from CO2) was 6.0±0.45 (using CO2) and 6.2±0.23 (using O2), an unusually low value for mammals. Also, repeatability of physiological variables was non-significant, as in previous studies, suggesting poor time-consistency of energy metabolism. Comparisons of energy expenditure and body temperature (using attached data-loggers) between grouped and isolated individuals showed that at 20°C both average resting metabolic rate and body temperature were higher in groups, essentially because animals remained non-torpid. At 10°C, however, all individuals became torpid and no differences were observed between grouped and isolated individuals. In summary, our study suggests that the main response of Dromiciops gliroides to low ambient temperature is reduced body temperature and torpor, irrespective of huddling. Low aerobic power and low time-consistency of most thermoregulatory traits of Dromiciops gliroides support the idea of poor thermoregulatory abilities in this species.

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“…Marsupial maternal investment is thought to be less costly than placental investment because the duration of pregnancy is so short that loss of a joey might have minimal consequences on lifetime reproductive output (Low, 1978; Clutton‐Brock, 1991). However, marsupial growth rates are slower than those of many mammals (Case, 1978; Russell, 1982; Westman, Korther & Geiser, 2002), which sets the stage for a prolonged period of maternal care that might be regulated by future offspring reproductive potential and entail reproductive costs to mothers. The reproductive energetics of marsupials are actually quite similar to those of placentals (Cork & Dove, 1989).…”

Section: Introductionmentioning

confidence: 99%

Maternal effort and joey growth in koalas (Phascolarctos cinereus)

et al. 2006

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The extent to which sex-biased maternal investment characterizes mammals is controversial, with less information available for evaluating patterns of maternal effort in marsupials than in placentals. Koalas Phascolarctos cinereus are sizedimorphic animals with a lengthy period of dependency and they reside in mating systems that might favour sex-biased maternal investment. We examined 18 years of data recorded from koalas living at the San Diego Zoo in order to examine how joey development and maternal condition might be connected. Koalas are pregnant for only 1 month, but joey emergence from the pouch does not occur until 32 weeks of age. Neither maternal condition nor age affected sex ratio at joey emergence, and both sexes had the same survivorship prospects. Koala dams transport and nurse joeys for close to 1 year, at which time the two sexes are size dimorphic. Given the poor-quality diet of koalas, combined with maternal transport of infants who are at least 25% of maternal mass, we suggest that infant rearing poses high energetic costs on koala females. We suggest that ecological and energetic constraints have moulded koala maternal strategies such that females maximize allocation of resources to offspring, regardless of sex, in order to increase prospects for joey survivorship.

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Developmental Thermoenergetics of the Dasyurid Marsupial, Antechinus Stuartii

Cited by 13 publications

References 33 publications

Costs of Reproduction and Terminal Investment by Females in a Semelparous Marsupial

Costs of Reproduction and Terminal Investment by Females in a Semelparous Marsupial

Aerobic power, huddling and the efficiency of torpor in the South American marsupial, Dromiciops gliroides

Maternal effort and joey growth in koalas (Phascolarctos cinereus)

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