Understanding the fantastic biodiversity that we see in the world requires both an understanding of the mechanisms generating such diversity and the selective forces that maintain it. Although the interplay between ecology and evolution has historically been separated by timescales, their complex interactions have recently become better recognized; notably so for viruses. My research focuses on the evolutionary ecology of viruses, both to understand viruses themselves, and as model systems for general questions in biology. My research began on experimental evolution of bacteria-infecting viruses (bacteriophages or phages), but more recently has expanded to include field studies of RNA viruses of eukaryotes. These viral systems are highly tractable, relevant to emerging infectious diseases, and accessible for both undergraduate and graduate students in the lab and classroom.