Model for the evolutionary origin of human globin loci.

Based on phylogenetic analysis, a model for the evolution of the vertebrate globins has been proposed11 and provides the evolutionary time-scale for the model depicted here. Genes are color coded; stippled lines indicate physical lineage but uncertainty about the order of the genes, the presence of additional genes, or both. Gray bars indicate when bony fishes diverged from agnathans, amphibians diverged from bony fishes, and mammals diverged from reptiles.36