My colleagues and I are conducting a long-term (12 years and counting), large-scale (four experimental populations in natural streams) study of the evolution and ecology of the Trinidadian guppy. Our experimental populations are the result of a transplant of guppies from a high-predation location to four low-predation locations. We have published a number of papers on the eco-evo feedbacks that emerge in this system. But there is still much to be learned and the project provides a diversity of opportunities for a postdoctoral scholar. First, we are continuing with our monthly mark-recapture census of our populations. This study provides data on population dynamics and, for every fish, data on size at maturity, morphological shape (from a photo archive), habitat use, and lifespan. This large database can be exploited to test a wide variety of ecological hypotheses about numerical dynamics and population regulation, the role of enhanced productivity in destabilizing dynamics, and many others. Second, for one of these populations we are building a pedigree for studies of quantitative genetics and reproductive success. A postdoctoral scholar interested in genetics can help extend the pedigree and use the data to test a number of hypotheses about trait evolution and quantitative genetics. In particular, we have documented substantial cryptic evolution in this population and the interaction of selection and environmental variation has emerged as a key factor in understanding guppy evolution. Third, we have built and maintained two separate artificial stream facilities in Trinidad. We use these facilities to perform focused experiments on the mechanisms driving natural selection, population dynamics, and community structure of tropical streams. A postdoctoral scholar can use these facilities in country to test a wide variety of ecological and evolutionary hypotheses.