phylogeography

Phylogeography is the study of historical processes that shape the geographic distributions of genealogical lineages, especially within species or among closely related species. It combines phylogenetics and biogeography to infer how events such as climate change, geology, range shifts, and population dynamics have produced present biodiversity patterns.

Data and methods: Analyses rely on genetic data—mitochondrial and nuclear DNA, SNPs, and increasingly whole genomes—together with geographic sampling. Methods include constructing genealogies or haplotype networks and applying coalescent or Bayesian models to estimate past population sizes, migration rates, and ancestral ranges. Common approaches use discrete models of ancestral areas (DEC, S-DIVA) and continuous phylogeography with models of spatial diffusion.

Applications: Phylogeography helps reconstruct postglacial recolonization routes, identify refugia, and detect barriers to gene flow, aiding conservation planning. It is used to study human migrations and to understand dispersal and range shifts in wildlife and plants.

Limitations: Inferences depend on sampling design, marker choice, and model assumptions. Gene flow, incomplete lineage sorting, and selection can complicate histories. Robust interpretations require integrating genetic results with fossil, ecological, and environmental data.