Bayesian-based phylogeny of Galápagos marine iguanas and distribution of mitochondrial clades based on mtDNA CR data. a) The topology and branch lengths were inferred using the program MRBAYES, but the rooting shown here was inferred using the software BEAST (see Methods). Branch lengths are in number of substitutions per site. Bayesian posterior probability values from MRBAYES are shown supporting the three major clades. b) Map of the Galápagos islands detailing population locations and symbols (details in Table 1). Pie charts illustrate the geographic distribution of the mtDNA CR clades resulting from the analysis of 1203 marine iguanas.