Classic life history theory is grounded in the assumption that investment in current reproduction reduces survival and future reproduction. However, Anolis lizards are special in the sense that they repeatedly lay a single egg at a time. This life history strategy is thought to have evolved to reduced the costs associated with investment in a large clutch of eggs. We are testing this hypothesis using a series of surgical manipulations that halt reproduction (Ovariectomy) and ecological manipulations that aim to measures the impact of extrinsic selective pressures. Our results have provided some surprising insights into the magnitude of reproductive costs that remain, despite the evolution of a single egg clutch.
Figure 1. Experimentally eliminating reproduction (OVX) increases survival relative to reproductive (SHAM) females. By measuring energetics and maintenance and quantifying survival of OVX and SHAM under replicated, whole-island manipulations of the predation regime, we can experimentally test the physiological and ecological mechanisms that structure this fundamental trade-off.
Related Publications
PDF Cox, R.M. and Calsbeek, R. Severe costs of reproduction persist in Anolis lizards despite the evolution of a single-egg clutch. Evolution 64: 1321-1330
Cox, R.M, *Parker, E.U., *Cheney, D.M., Liebl, A.L., Martin, L.B., and Calsbeek, R. Experimental evidence for physiological costs underlying the trade-off between reproduction and survival. Functional Ecology in press