Given genetically determined variations in behavior (among individuals of a species), natural selection will favor those variants with the most appropriate behavior for their environment. Thus, in order to fully understand the evolution of behavior, one needs to know at least two things: the degree to which the behavior of interest is under genetic control, and the ecological milieu in which the behavior occurs. In bees and wasps, females have behavioral control over the sex of their offspring and, given this, they produce different ratios of sons and daughters in different environments. A deep theoretical understanding of the ecological forces selecting for particular sex ratios has developed over the past two decades. This theory is able to account for many of the patterns of sex- ratio production observed in bees and wasps (as well as many other organisms). However, two broad gaps remain in our knowledge. While the patterns of sex-ratio production are well documented, little is known regarding the environmental cues leading females to vary the sex ratio, nor do we understand the behavioral processes by which different sex ratios are produced. Yet it is at these levels--variation in the responsiveness to environmental cues and variation in the processes of sex-ratio production--that genetics becomes a significant component of behavior. Secondly, because many wasps and bees are difficult to study in nature, our knowledge of their ecology, as it relates to sex-ratio theory, is often scanty. In order to truly test the theories, detailed accounts of the relevant ecology are needed for a variety of species. Dr. Skinner's research is aimed at filling these gaps by utilizing a wasp that is uniquely amenable to both genetic and ecological research. The goals of this project are (1) to experimentally dissect the behaviors of different wasp genotypes to (a) determine what, mechanistically, leads them to produce different sex ratios, (b) determine the environmental cues that elicit different sex-ratio behaviors, and (c) determine the degree to which "different" sex-ratio behaviors are fundamentally integrated by common underlying mechanisms, (2) to videotape egg- laying in seminatural settings in order to assess the relative contributions of different behaviors to the overall sex ratios produced by individual females, and (3) to observe mating and egg-laying behaviors in nature to provide a detailed ecological framework for laboratory studies of sex-ratio behavior.
