Phylogeography is the study of the historical processes that shape the geographic distribution of species and populations. It combines principles from phylogenetics, which examines evolutionary relationships, with geography to understand how environmental factors influence genetic variation and species distribution over time. By analyzing genetic data, researchers can trace the lineage of organisms and identify how geographical barriers, such as mountains or rivers, affect their movement and evolution. This field helps scientists understand biodiversity, species migration patterns, and the impact of climate change on ecosystems, contributing to conservation efforts and ecological studies.