Fig. 1

A hypothetical example of a four-node cycle in a haplotype network. The example indicates a hypothetical DNA sequence where two nucleotide changes occur at position 10 and 20. Circles (nodes) correspond to genotypes. An edge connects two nodes if they differ by a single mutation. Lettering next to each node indicates the nucleotides at which two genotypes differ. Edge labels show changes required to create a genotype from its neighbor, e.g., “A20G” indicates a change from A to G at position 20 of the hypothetical sequence. In the example, mutations at positions 10 and 20 create genotypes 2 and 3 from genotype 1 . Then, either genotype 2 mutates at position 20 from A to G, or genotype 3 mutates at position 10 from A to T, or both of these mutations take place, and create genotype 4