My research focuses on the processes that generate and threaten biological diversity. How are new species formed and why are species being lost at such an alarming rate in our contemporary world? Specifically, I am interested in the fundamental processes that affect biodiversity: speciation and extinction. I focus on understanding mechanisms of rapid evolution across levels of organization -- from genes to ecosystems. I am motivated by research questions that cross scales, and my lab uses diverse methods from field studies to laboratory experiments to full-genome sequencing. For this seminar, I will present recent results from studies on two core systems I have been developing over the last decade. I will discuss insights into wildlife declines gained from studying disease-related extinctions in amphibian populations. I will then discuss insights into evolutionary predictability gained from studying rapid adaptation in desert lizard populations. Overall I hope to share the importance of understanding organismal response to changing environments.