Paul Andersen reviews the major concepts within the second unit of the new AP Biology framework. He starts by describing how life is organized into three domains. He explains how the history of life on the planet is characterized by mass extinctions followed by adaptive radiation. He explains how geographic, behavioral, temporal and mechanical isolation can create new species. He also explains how microevolution within a population can explain. He ends the podcast by describing abiogenesis and mentioning the major milestones in the evolution of life on the planet.