Haplotype network constructed under statistical parsimony for all Galápagos marine iguana mtDNA CR haplotypes. Haplotype numbers are preceded by the letter "H." The smallest circles denote missing haplotypes. The other four circle sizes reflect the number of individuals. In order of increasing area, this corresponds to 1-6, 7-20, 21-50, and 50 or more individuals. All singletons were removed from populations on Fernandina and western Isabela in order to more clearly display the overall phylogeographic patterns. Island distribution of each haplotype is indicated by color according to the embedded legend.