Genetic hubs: a phylogeographer’s widget for pinpointing of ancestral populations

Statistical phylogeography benefits from the development of increasingly realistic models of spatially structured genetic variation. Their fitting, however, is computationally demanding and requires population and/or genomic sampling that is not available for many species of interest. Genetic hubs is a method that can be used for exploratory analyses of various kinds of genetic data, including those as typical in mitochondrial phylogeography, i.e. many small samples of single locus genotypes scattered throughout the species distributional range. Genetic hubs allows to quantify and visualize gradients of genetic variation with the aim to pinpoint possible origin of expansion. It estimates local genetic variability as an accessibility of all genetic variation from the site in question and it allows to take dissimilarity of genotypes into account. The method represents fast and versatile tool that can be used whenever history of range expansion is assumed to shape the observed distribution of genetic variation and it is useful especially for preliminary analyses whose purpose is to provide sound basis for formulation of testable hypotheses and design of follow-up studies.