Antonovics 9520793 To evaluate the appropriateness of using a kin selectionist framework to explain worker behavior, the origin(s) of sex ratio differences between colonies of the ant, Leptothorax curvispinosus, will be elucidated. Oviposition sex ratios will be determined by flow cytometry (a novel application of this technology) and compared with the following year's adult sex ratios. A marked disparity between oviposition and adult sex ratios would suggest that workers may indeed manipulate brood sex ratios to their inclusive fitness benefit; possible mechanisms will be investigated experimentally. The possible role of historical distorter invasion will be explored through computer simulation and genetic models. Initial simulations of this "distorter invasion hypothesis" suggest an interpretation of eusociality that differs significantly from the kin selectionist explanation, in essence arguing that invasion creates predictable, oscillating mate limitations, and that worker behavior is an adaptive response under such circumstances.