Costs of reproduction
Classic life-history theory is based around the idea that investment in reproduction compromises survival. But what is the functional basis of this tradeoff? Which aspects of reproduction render it costly? Is this tradeoff generated mostly by intrinsic factors (e.g., self-maintenance) or by extrinsic sources of mortality (e.g., predators)? We approach these questions using experimental manipulations of reproductive investment and mark-recapture studies in the wild.
The figure above summarizes experimental studies of the tradeoff between reproduction and survival in female anoles. By eliminating reproductive investment via surgical ovariectomy (OVX), we can dramatically increase survival, energy storage, maintenance physiology, and locomotor performance relative to intact (SHAM) females. We're using similar approaches to ask whether different individuals, sexes, and genetic morphs balance these costs in different ways.
What is the ecological basis of the tradeoff between reproduction and survival? Although predator exclusion (netted island, above) and addition experiments show that mortality is greater in the presence of snake predators, we find no evidence that predators differentially influence survival of OVX and SHAM females. Instead, the survival and growth costs of reproduction increase as average body condition (an index of environmental quality) increases across islands. Natural selection on body size also changes as a function of average body condition (Cox et al. 2021).
Relevant publications
Cox, R.M., T.N. Wittman, and R. Calsbeek. 2021. Reproductive tradeoffs and phenotypic selection change with body condition, but not with predation regime, across island lizard populations. Journal of Evolutionary Biology
Reedy, A.M., W.J. Evans and R.M. Cox. 2019. Sexual dimorphism explains residual variance around the survival-reproduction tradeoff in lizards: Implications for sexual conflict over life-history evolution. Evolution 73: 2324-2332.
Reedy, A.M., C.L. Cox, A.K. Chung, W.J. Evans, and R.M. Cox. 2015. Both sexes suffer increased parasitism and reduced energy storage as costs of reproduction in the brown anole, Anolis sagrei. Biological Journal of the Linnean Society 117: 516-527.
Cox, R.M., M.B. Lovern and R. Calsbeek. 2014. Experimentally decoupling reproduction and energetics to test the functional basis of a life-history tradeoff. Journal of Animal Ecology 83: 888-898.
Cox, R.M. 2014. Integrating costs of reproduction between the sexes. Chapter 10 in Integrative Organismal Biology, edited by L.B. Martin, H.A. Woods, and C. Ghalambor. Wiley Scientific.
Cox, R.M., and R. Calsbeek. 2011. An experimental test for alternative reproductive strategies underlying a female-limited polymorphism. Journal of Evolutionary Biology 24: 343-353.
Cox, R.M., and R. Calsbeek. 2010. Severe costs of reproduction persist in Anolis lizards despite the evolution of a single-egg clutch. Evolution 64: 1321-1330.
Cox, R.M., E.U. Parker, D.M. Cheney, A.L. Liebl, L.B. Martin, and R. Calsbeek. 2010. Experimental evidence for physiological costs underlying the trade-off between reproduction and survival. Functional Ecology 24: 1262-1269.
Cox, R.M. 2006. A test of the reproductive cost hypothesis for sexual size dimorphism in Yarrow’s spiny lizard, Sceloporus jarrovii. Journal of Animal Ecology 75: 1361-69.
Cox, R.M., T.N. Wittman, and R. Calsbeek. 2021. Reproductive tradeoffs and phenotypic selection change with body condition, but not with predation regime, across island lizard populations. Journal of Evolutionary Biology
Reedy, A.M., W.J. Evans and R.M. Cox. 2019. Sexual dimorphism explains residual variance around the survival-reproduction tradeoff in lizards: Implications for sexual conflict over life-history evolution. Evolution 73: 2324-2332.
Reedy, A.M., C.L. Cox, A.K. Chung, W.J. Evans, and R.M. Cox. 2015. Both sexes suffer increased parasitism and reduced energy storage as costs of reproduction in the brown anole, Anolis sagrei. Biological Journal of the Linnean Society 117: 516-527.
Cox, R.M., M.B. Lovern and R. Calsbeek. 2014. Experimentally decoupling reproduction and energetics to test the functional basis of a life-history tradeoff. Journal of Animal Ecology 83: 888-898.
Cox, R.M. 2014. Integrating costs of reproduction between the sexes. Chapter 10 in Integrative Organismal Biology, edited by L.B. Martin, H.A. Woods, and C. Ghalambor. Wiley Scientific.
Cox, R.M., and R. Calsbeek. 2011. An experimental test for alternative reproductive strategies underlying a female-limited polymorphism. Journal of Evolutionary Biology 24: 343-353.
Cox, R.M., and R. Calsbeek. 2010. Severe costs of reproduction persist in Anolis lizards despite the evolution of a single-egg clutch. Evolution 64: 1321-1330.
Cox, R.M., E.U. Parker, D.M. Cheney, A.L. Liebl, L.B. Martin, and R. Calsbeek. 2010. Experimental evidence for physiological costs underlying the trade-off between reproduction and survival. Functional Ecology 24: 1262-1269.
Cox, R.M. 2006. A test of the reproductive cost hypothesis for sexual size dimorphism in Yarrow’s spiny lizard, Sceloporus jarrovii. Journal of Animal Ecology 75: 1361-69.