Antonovics 9408207 The ecological and evolutionary impact of sexually transmitted diseases (STD's) has rarely been studied in a non-medical context; they have been considered a minor type of infectious disease in natural systems. The investigators' initial studies have shown that STD's are abundant within the animal kingdom and that they have many shared characteristics (low disease induced mortality, long span of infectious period, narrow host ranges, sterility, less population cycling). This study will use theoretical models to investigate (a) the factors that influence evolution towards sexual versus other modes of disease transmission, (b) the coevolution of pathogen characteristics and host mating systems, and (c) the effect of spatial structure on stability and evolution of STD's STD's can have important consequences for population regulation and for the evolution of mating systems. The study of their population biology is also relevant for interpreting and predicting the emergence of new diseases. The present study will bear directly on these issues.
