9307999 Sinervo An increase of energy invested in current reproduction is thought to entail :costs" that are either reflected in a decrease in survival or a decrease in future reproductive success. We have devised an experimental test of these ideas in a natural population of lizards. By experimentally enhancing the number of eggs in a clutch using a hormonal treatment, we should exacerbate those costs and decrease survival or future reproductive success. A complementary manipulation that decreases the number of eggs laid in each clutch should ameliorate these costs and enhance survival or future reproductive success. Because the hormones that control reproduction are relatively conserved among vertebrates (e.g., reptiles, mammals, birds, fish), our results are likely to be quite general. Consequently, these results will be relevant to domestic animal husbandry (e.g. aquaculture, bird rearing, etc.) and these results could theoretically be used to maximize yield in such agricultural programs.***
