Interactive effects of sex, social environment, dietary restriction, and methionine on survival and reproduction in fruit flies
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For the evolution of life histories, the trade-off between survival and reproduction is fundamental. Because sexes optimize fitness in different ways, this trade-off is expected to be resolved differently by males and females. Consequently, the sexes are predicted to respond differently to changes in resource availability. In fruit flies, research on dietary restriction has focused largely on females maintained in the absence of males, thereby neglecting sexual interactions that affect reproductive behavior of both sexes under more natural conditions. Here, we tested for the interactive effects of diet (40, 60, 100, and 300 % of standard yeast concentrations) and social environment (separate-sex vs. mixed-sex groups) on male and female Drosophila melanogaster life histories. Additionally, we evaluated the essential amino acid methionine as an agent that can uncouple the survival–reproduction trade-off. We show sex differences in the effect of social environment on survival patterns, but not on reproductive fitness. In females, yeast had a positive effect on reproduction and a negative effect on survival. In males, yeast had a negative effect on reproduction and the effect on survival depended on the social environment. Methionine reduced survival, but had no effect on reproduction. Our findings highlight the need to include both sexes and to vary social environments in research programs aimed at lifespan extension and call for further evaluation of the fecundity-restoring effect of methionine.
KeywordsSex differences Cost of reproduction Senescence Mortality Dietary restriction
We thank Henrik Lysell for his help during the experiment. The study was supported by a scholarship from the Wenner-Gren Foundations to F.Z., by grants from the Swedish Research Council to A.A.M and U.F., a grant from the Swedish Foundation for Strategic Research to U.F., and a European Research Council Starting Grant 2010 to A.A.M.
- Bolker B (2008) Ecological models and data in R. Princeton University Press, PrincetonGoogle Scholar
- Kirkwood TBL (1977) Evolution of aging. Nature 270:301–304Google Scholar
- Miller RA, Buehner G, Chang Y, Harper JM, Sigler R, Smith-Wheelock M (2005) Methionine-deficient diet extends mouse lifespan, slows immune and lens aging, alters glucose, T4, IGF-I and insulin levels, and increases hepatocyte MIF levels and stress resistance. Aging Cell 4:119–125PubMedCrossRefGoogle Scholar
- Pinheiro J, Bates D, DebRoy S, Sarkar D (2009) nlme: linear and nonlinear mixed effects models. R package version 3:1–96Google Scholar
- Roff DA (2002) Life history evolution. Sinauer associates, Sunderland, Massachusetts, USAGoogle Scholar
- Stearns SC (1992) The evolution of life histories. Oxford University Press, New YorkGoogle Scholar
- Therneau T (2011a) R package ‘coxme’. R package version 2:1–3Google Scholar
- Therneau T (2011b) R package ‘survival’. R package version 2. 36–10Google Scholar
- Trivers RL (1972) Parental investment and sexual selection. In: Campbell B (ed) Sexual selection and the descent of man, 1871–1971. Aldine Publishing Co., Chicago, pp 136–179Google Scholar