Physical barriers significantly influence species distribution by restricting movement and gene flow among populations. These include geographical features like mountains, rivers, and oceans, which can separate distinct habitats and create unique ecological niches. For example, rivers may prevent aquatic species from migrating, leading to divergent evolutionary paths. Additionally, these barriers can impact resource availability, reproductive success, and ultimately drive speciation. Understanding these dynamics is crucial for conservation efforts and predicting how species will respond to environmental changes.