Meeting Abstract

23.4  Monday, Jan. 4  The ecology of life-history trade-offs: whole-island manipulations of predation regime in a wild lizard COX, Robert M.*; CALSBEEK, Ryan; Dartmouth College robert.m.cox@dartmouth.edu

A central tenet of life-history theory is that investment in reproduction compromises survival. Here, we use experimental manipulations of reproductive investment to show that reproduction severely compromises survival in a wild population of brown anole lizards (Anolis sagrei). In each of three separate years, elimination of reproductive investment via surgical ovariectomy dramatically increased the survival of female anoles, relative to reproductive shams. Gravid females also suffered significant reductions in sprint speed and stamina, suggesting that their impaired locomotor performance may render them more susceptible to predators. To determine whether the survival cost of reproduction is driven by predator-induced mortality, we combined surgical manipulations of reproductive investment with whole-island manipulations of predation regime (via bird exclusion and/or snake addition). Ovariectomized and sham females were released to replicate islands exposed to (1) bird predators, (2) bird and snake predators, or (3) no predators. Exclusion of bird predators did not influence mortality, but addition of snake predators increased mortality. However, surgical treatment groups did not differ in survival under any predation regime, suggesting that the trade-off between reproduction and survival is not driven by extrinsic, predator-induced mortality. Instead, the low survival of reproductive females may reflect the energetic demands of egg production.