I would like to thank Jim Brown, Stephanie Forrest, John Holland, and Terry Jones for insight on the Echo Gecko findings, and Leo Buss for discussions on allometry, observed trophic efficiencies, and barnacles. This incarnation of Gecko is based on the Swarm simulation platform. The Santa Fe Institute Swarm development team, especially Nelson Minar, provided superb support to the Swarm beta test group. Günter Wagner introduced me to Rechenberg's work on Evolution Strategy, and is an all-around wonderful boss. Oswald Schmitz, as principal investigator on Gecko, has given me great freedom to explore, and been patient when my choices were based on software rather than science. I'm also grateful to two anonymous reviewers whose encouraging comments helped focus this paper. Support for this research was generously provided by NSF grant # BIR 9400642 to Leo Buss, Oswald Schmitz, and Günter Wagner, the Yale School of Forestry and Environmental Studies, the Yale Institute for Biospheric Studies, and computer equipment donations from Hewlett-Packard. This is contribution #43 of the Yale Center for Computational Ecology.