Maternal Investment and Neonatal Growth in Phocid Seals

Kovacs, Kit M.; Lavigne, D. M.

doi:10.2307/4432

Cited by 153 publications

(97 citation statements)

References 89 publications

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“…The arrival mass of females for the breeding season is vital for successful pup production as maternal expenditure is limited by initial body condition (Laws 1953;Kovacs et al 1986;Trillmich 1996).…”

Section: Maternal Age and Expenditurementioning

confidence: 99%

“…A larger weaning mass would imply that pups have a larger reserve for development in the post-weaning phase. Large birth size and fast growth of phocid pups during the suckling period is advantageous in obtaining adequate blubber for thermoregulation (Bryden 1969;Kovacs et al 1986) during the following protracted post weaning phase (Worthy et al 1983). During their post weaning phase pups grow and simultaneously lose mass, up to 30% of their weaning mass at MI (Wilkinson et al 1990).…”

Section: Offspring Survivalmentioning

confidence: 99%

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Age-related reproductive variation in a wild marine mammal population

2013

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Life history theory predicts a change in reproduction success with age as energy resources are limited and must be allocated effectively to maximise reproduction and survival. In this study we use three reproductive performance measures; maternal expenditure, offspring weaning mass and first year survival to investigate the role maternal age plays in successful reproduction. Long-term uninterrupted life history data available for Marion Island's southern elephant seals and mass change estimates from photogrammetry data allow for assessment of age related reproduction performance and trade-offs. Known-aged adult females were photographed for photogrammetric mass estimation (n=29) and their pups weighed at weaning during the 2009 breeding season. Maternal age and proportional mass loss positively influenced pup weaning mass. In turn first year pup return rates (as a proxy for survival) were assessed through the intensive mark-recapture program.Pup survival increased with female age and weaning mass. Pups of young females aged 3 to 6 years have a lower 1 st year survival probability compared to pups of older and larger females.

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Section: Maternal Age and Expenditurementioning

confidence: 99%

Section: Offspring Survivalmentioning

confidence: 99%

Age-related reproductive variation in a wild marine mammal population

2013

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“…Indeed, they may run down their reserves to reduce any insulative effect of the fat, to maximise heat dissipation, which is probably a key limiting factor on lactation performance (Król and Speakman, 2003;Król et al, 2007a,b;Speakman and Król, 2011). At the other extreme, some breeding seals accumulate body fat and then do not feed at all during lactation, relying entirely on this reserve to synthesise milk that is continuously transferred to their offspring (Bowen et al, 1985(Bowen et al, , 1992Kovacs and Lavigne, 1986;Iverson et al, 1993). Numerous animals follow intermediate strategies (e.g.…”

Section: Introductionmentioning

confidence: 99%

The evolution of body fatness: trading off disease and predation risk

Speakman

2018

Journal of Experimental Biology

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Human obesity has a large genetic component, yet has many serious negative consequences. How this state of affairs has evolved has generated wide debate. The thrifty gene hypothesis was the first attempt to explain obesity as a consequence of adaptive responses to an ancient environment that in modern society become disadvantageous. The idea is that genes (or more precisely, alleles) predisposing to obesity may have been selected for by repeated exposure to famines. However, this idea has many flaws: for instance, selection of the supposed magnitude over the duration of human evolution would fix any thrifty alleles (famines kill the old and young, not the obese) and there is no evidence that hunter-gatherer populations become obese between famines. An alternative idea (called thrifty late) is that selection in famines has only happened since the agricultural revolution. However, this is inconsistent with the absence of strong signatures of selection at single nucleotide polymorphisms linked to obesity. In parallel to discussions about the origin of obesity, there has been much debate regarding the regulation of body weight. There are three basic models: the setpoint, settling point and dual-intervention point models. Selection might act against low and high levels of adiposity because food unpredictability and the risk of starvation selects against low adiposity whereas the risk of predation selects against high adiposity. Although evidence for the latter is quite strong, evidence for the former is relatively weak. The release from predation ∼2-million years ago is suggested to have led to the upper intervention point drifting in evolutionary time, leading to the modern distribution of obesity: the drifty gene hypothesis. Recent critiques of the dual-intervention point/ drifty gene idea are flawed and inconsistent with known aspects of energy balance physiology. Here, I present a new formulation of the dual-intervention point model. This model includes the novel suggestion that food unpredictability and starvation are insignificant factors driving fat storage, and that the main force driving up fat storage is the risk of disease and the need to survive periods of pathogen-induced anorexia. This model shows why two independent intervention points are more likely to evolve than a single set point. The molecular basis of the lower intervention point is likely based around the leptin pathway signalling. Determining the molecular basis of the upper intervention point is a crucial key target for future obesity research. A potential definitive test to separate the different models is also described.

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“…Capital breeders, animals that provision their offspring from energy reserves, are often the focus of maternal-care studies because effort can be determined from changes in body condition (Kovacs and Lavigne 1986;Iverson et al 1993;Crocker et al 2001). In capital breeders, size and condition are strongly correlated to reproductive effort and success (Festa-Bianchet et al 1998;Côte and Festa-Bianchet 2001;Crocker et al 2001); however, most mammals are income breeders, animals that provision offspring from current food intake.…”

Section: Dynamic Influence Of Maternal and Pup Traits On Maternal Carmentioning

confidence: 99%

Dynamic Influence of Maternal and Pup Traits on Maternal Care during Lactation in an Income Breeder, the Antarctic Fur Seal

McDonald¹,

Goebel²,

Crocker³

et al. 2012

Physiological and Biochemical Zoology

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Life-history theory predicts that selection will favor optimal levels of parental effort that balance benefits of current reproduction with costs to survival and future reproduction. The optimal level of effort depends on parental traits, offspring traits, and provisioning strategy. Additionally, how these factors influence effort may differ depending on the stage of reproduction. The relative importance of maternal and offspring traits on energy allocation to offspring was investigated in known-age Antarctic fur seals Arctocephalus gazella across four stages of reproduction, using birth mass and milk-consumption measurements. Maternal traits were important during three of the four stages investigated, with larger females giving birth to larger pups and investing more in pups during perinatal and molt stages. Pup mass influenced maternal effort during the premolt stage, and provisioning strategy influenced postnatal maternal effort at all stages. Energy provided to the offspring during an attendance visit was positively related to the duration of the foraging-trip/visit cycle; however, when investment was controlled for trip/visit cycle duration, the overall rate of energy transfer was similar across trip durations. In addition to strong effects of maternal mass, pup traits affected energy allocation, suggesting that pup demand is important in determining maternal care. These findings emphasize the importance of considering state variables in life-history studies and suggest that timing of measurements of effort in species with long provisioning periods may influence conclusions and our ability to make comparisons of reproductive effort among species.

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Maternal Investment and Neonatal Growth in Phocid Seals

Cited by 153 publications

References 89 publications

Age-related reproductive variation in a wild marine mammal population

Age-related reproductive variation in a wild marine mammal population

The evolution of body fatness: trading off disease and predation risk

Dynamic Influence of Maternal and Pup Traits on Maternal Care during Lactation in an Income Breeder, the Antarctic Fur Seal

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