Current patterns of gene flow may bear little resemblance to the historical connections among populations, but both are relevant to the contemporary distributions of species and their genes. Understanding how historical events have helped to shape the current geographical dispersion of genes, populations and species is the major goal of phylogeography, a term that was introduced by Avise in 1987 (Avise et al., 1987). Phylogeography can be defined as a '... field of study concerned with the principles and processes governing the geographic distributions of genealogical lineages, especially those within and among closely related species' (Avise, 2000). By comparing the evolutionary relationships of genetic lineages with their geographical locations, we may gain a better understanding of which factors have most influenced the distributions of genetic variation. Phylo-geography therefore embraces aspects of both time (evolutionary relationships) and space (geographical distributions).
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