5 Phylogeography What is Phylogeography? 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. | 5 Phylogeography What is Phylogeography 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 . Molecular Markers in Phylogeography Phylogeography is concerned with the distribution of genealogical lineages and we know from Chapter 2 that DNA sequences are the markers that are best suited for inferring genealogies. A looser interpretation of phylogeography does allow the use of markers such as microsatellites and AFLPs that provide information about the genetic similarity of populations based on allele frequencies or bandsharing although strictly speaking such data do not comply with Avise s original definition of phylogeography. Nevertheless as we saw in Chapter 4 allele frequencies can provide us with information on gene flow and the genetic subdivision of Molecular Ecology Joanna Freeland 2005 John Wiley Sons Ltd. 156 PHYLOGEOGRAPHY populations and therefore often make useful contributions to studies of phylogeo-graphy. Over the years the markers of choice at least when studying animals have been mitochondrial sequences that were obtained through either .
