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Seal mothers expend more on offspring under favourable conditions and less when resources are limited

Citation

McMahon, CR and Harcourt, RG and Burton, HR and Daniel, O and Hindell, MA, Seal mothers expend more on offspring under favourable conditions and less when resources are limited, Journal of Animal Ecology, 86, (2) pp. 359-370. ISSN 0021-8790 (2017) [Refereed Article]

Copyright Statement

Copyright 2016 The Authors. Journal of Animal Ecology Copyright 2016 British Ecological Society

DOI: doi:10.1111/1365-2656.12611

Abstract

  • In mammals, maternal expenditure on offspring is a complex mix of several factors including the species’ mating system, offspring sex and the condition and age of the mother. While theory suggests that in polygynous species mothers should wean larger male offspring than females when resources and maternal conditions allow, the evidence for this remains equivocal.
  • Southern elephant seals are highly dimorphic, polygynous capital breeders existing in an environment with highly variable resources and should therefore provide clear evidence to support the theoretical expectations of differential maternal expenditure in male and female pups.
  • We quantified maternal size (mass and length) and pup size at birth and weaning for 342 elephant seal mothers at Macquarie Island. The study was conducted over 11 years of contrasting sea-ice and Southern Annular Mode values, both indices of maternal prey resources.
  • Overall, large females weaned male pups that weighed 17 kg (15·5%) more than female pups. Maternal condition varied by as much as 59 kg among years, and was positively related to Southern Annular Mode, and negatively to maximum sea-ice extent. Smaller mothers weaned relatively larger male pups under favourable conditions, this effect was less apparent for larger mothers.
  • We developed a simple model linking environmental variation to maternal masses post-partum, followed by maternal masses post-partum to weaning masses and then weaning masses to pup survival and demonstrated that environmental conditions affected predicted survival so that the pups of small mothers had an estimated 7% increase in first year survival in ‘good’ vs. ‘bad’ years compared to 1% for female pups of large mothers.
  • Co-occurrence of environmental quality and conservative reproductive tactics suggests that mothers retain substantial plasticity in maternal care, enhancing their lifetime reproductive success by adjusting reproductive expenditure relative to both prevailing environmental conditions and their own capabilities.
  • Item Details

    Item Type:Refereed Article
    Keywords:seals, Antarctic, habitat, Antarctica, Integrated Marine Observing System, life history
    Research Division:Biological Sciences
    Research Group:Ecology
    Research Field:Marine and Estuarine Ecology (incl. Marine Ichthyology)
    Objective Division:Environment
    Objective Group:Ecosystem Assessment and Management
    Objective Field:Ecosystem Assessment and Management of Antarctic and Sub-Antarctic Environments
    Author:McMahon, CR (Dr Clive McMahon)
    Author:Daniel, O (Mr Owen Daniel)
    Author:Hindell, MA (Professor Mark Hindell)
    ID Code:113977
    Year Published:2017
    Web of Science® Times Cited:3
    Deposited By:Centre for Ecology and Biodiversity
    Deposited On:2017-02-01
    Last Modified:2017-11-08
    Downloads:0

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