The key principles of evolution include variation, inheritance, natural selection, and adaptation. Variation refers to the differences in traits among individuals within a population, often resulting from genetic mutations. Inheritance ensures that beneficial traits can be passed to offspring. Natural selection, a critical mechanism of evolution, favors individuals whose traits provide a survival or reproductive advantage in their environment, leading to gradual changes in populations over time. Adaptation is the process by which species develop traits that enhance their fitness in specific environments. Together, these principles explain how species evolve and diversify through generations.