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Despite Catch-Up, Prolonged Growth Has Detrimental Fitness Consequences in a Long-Lived Vertebrate
Dominique Marcil-Ferland, Marco Festa-Bianchet, Alexandre M. Martin and Fanie Pelletier
The American Naturalist
Vol. 182, No. 6 (December 2013), pp. 775-785
Stable URL: http://www.jstor.org/stable/10.1086/673534
Page Count: 11
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AbstractIndividuals experiencing poor growth early in life may later make up their size deficit. Compensatory growth or growth prolongation may lead to such catch-up, involving different life-history trade-offs under natural conditions. Frequent recaptures and detailed monitoring of animals surviving to asymptotic size are required to compare growth tactics and their fitness consequences. No study to date has obtained such detailed information for wild animals. We used repeated mass measurements (mean 11.6/animal) spanning the lifetime of 104 bighorn ewes (Ovis canadensis) to quantify growth tactics and identify the determinants and life-history costs of these tactics. Growth prolongation, not compensatory growth, led to partial catch-up: mass difference at age 7 was reduced to 4%, for two groups that differed by nearly 20% as yearlings. Ewes that had been light as yearlings prolonged their growth regardless of density or age of primiparity. Growth prolongation did not affect fecundity or longevity. Ewes that experienced poor early growth prolonged growth at the expense of reproductive fitness, weaning a smaller proportion of their lambs. By tracking multiyear growth patterns and comparing events at different life-history stages, we quantified a trade-off between growth and reproduction that would be overlooked if only the adult phenotype was considered. Compensatory growth in long-lived animals appears unlikely when early growth restrictions are mostly density dependent.
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