Maternal, social and abiotic environmental effects on growth vary across life stages in a cooperative mammal

Authors

  • Sinead English,

    Corresponding author
    1. Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge
    • Correspondence and present address: Sinead English, Edward Grey Institute, Department of Zoology, University of Oxford, Oxford OX1 3PS UK.

      Email: sineadenglish@cantab.net

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  • Andrew W. Bateman,

    1. Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge
    Current affiliation:
    1. Department of Biology/Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Canada
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  • Rafael Mares,

    1. Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge
    Current affiliation:
    1. Institute of Scientific Research and High Technology Services, Panama City, Panama
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  • Arpat Ozgul,

    1. Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge
    Current affiliation:
    1. Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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  • Tim H. Clutton-Brock

    1. Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge
    2. Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
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  • [Correction added after online publication 20 January 2014: author affiliations corrected]

    [Correction added on 5 August 2014 after first online publication: copyright legal statement changed to CC-BY]

Summary

  1. Resource availability plays a key role in driving variation in somatic growth and body condition, and the factors determining access to resources vary considerably across life stages. Parents and carers may exert important influences in early life, when individuals are nutritionally dependent, with abiotic environmental effects having stronger influences later in development as individuals forage independently.
  2. Most studies have measured specific factors influencing growth across development or have compared relative influences of different factors within specific life stages. Such studies may not capture whether early-life factors continue to have delayed effects at later stages, or whether social factors change when individuals become nutritionally independent and adults become competitors for, rather than providers of, food.
  3. Here, we examined variation in the influence of the abiotic, social and maternal environment on growth across life stages in a wild population of cooperatively breeding meerkats. Cooperatively breeding vertebrates are ideal for investigating environmental influences on growth. In addition to experiencing highly variable abiotic conditions, cooperative breeders are typified by heterogeneity both among breeders, with mothers varying in age and social status, and in the number of carers present.
  4. Recent rainfall had a consistently marked effect on growth across life stages, yet other seasonal terms only influenced growth during stages when individuals were growing fastest. Group size and maternal dominance status had positive effects on growth during the period of nutritional dependence on carers, but did not influence mass at emergence (at 1 month) or growth at independent stages (>4 months). Pups born to older mothers were lighter at 1 month of age and subsequently grew faster as subadults. Males grew faster than females during the juvenile and subadult stage only.
  5. Our findings demonstrate the complex ways in which the external environment influences development in a cooperative mammal. Individuals are most sensitive to social and maternal factors during the period of nutritional dependence on carers, whereas direct environmental effects are relatively more important later in development. Understanding the way in which environmental sensitivity varies across life stages is likely to be an important consideration in predicting trait responses to environmental change.

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