The primary mechanism of evolutionary change is natural selection. This process occurs when individuals with advantageous traits are more likely to survive and reproduce in a given environment, passing those traits to the next generation. Over time, these adaptations accumulate, resulting in changes within populations. Other mechanisms, such as mutation, gene flow, and genetic drift, also contribute to evolutionary change, but natural selection remains the key driver shaping the diversity of life on Earth. Understanding these mechanisms is crucial for studying biodiversity and species adaptation.