The phenomenon I thought of as a complex adaptive system is a spread of a disease, caused by a bacteria or virus, among a species of organism. The agents are the disease causing pathogen, the species of organism, and the resources (food) in which the species depend on. The environment is the ecosystem in which the species live. The interactions: the more resources the species is able to obtain, the higher the chances the species has to survive and reproduce, increasing its population. But if the species come into contact with the pathogen, the species will get the disease, become sick, and die, decreasing its population.