Abstract # 99:

Scheduled for Sunday, September 20, 2009 11:45 AM-11:55 AM: Session 8 (Shell Room) Oral Presentation


LIFE HISTORY TRADEOFFS OF LITTER SIZE AT BIRTH IN THE COMMON MARMOSET (CALLITHRIX JACCHUS)

J. N. Rutherford
Northwestern University, Department of Anthropology, Evanston, IL 60208, USA
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Life history parameters such as age at first reproduction, reproductive tenure, and offspring production and survivorship have deep roots in developmental processes during fetal life, processes reflected by birth weight, litter number, and placental function. The marmosets and tamarins are characterized as regularly producing twins, but this generalization obscures important energetically-driven flexibility in reproductive output. The current study sought to determine the effect of litter size and weight at birth on life history milestones in common marmoset (Callithrix jacchus) females from a captive colony at the Southwest National Primate Research Center in San Antonio, TX. In multiple linear regression models controlling for the effects of age, weight, and maternal characteristics, a female’s litter size at birth emerged as a strong predictor of age at first reproduction [β=-0.68, t=-2.77, p=0.01] and ratio of reproductive years [β=0.11, t=2.23, p=0.03], and was the second best predictor of total number of offspring produced [β=2.08, t=1.09, p=0.29]. However, aside from an individual’s own litter size, the best predictor of perinatal mortality was maternal litter size [odds ratio=2.59; 95% CI=1.09-6.16, p=0.03]. These patterns suggest that being born a triplet entails both costs and benefits for later reproductive fitness, and that intergenerational tradeoffs need to be considered in the reconstruction of life history evolution in the callitrichine primates.