Multigene families include two or more nearly identical genes with related functions. A classical example is the set of genes for globin molecules, including genes on human chromosomes 11 and 16. Some of these genes produce hemoglobin only in the fetus or embryo. Others are very similar to functional genes, but have accumulated mutations and are no longer functional. A scheme of alpha globin gene family and beta globin gene family. The alpha globin gene cluster is located on chromosome 16 and includes the loci zeta, pseudozeta, pseudoalpha-2, pseudoalpha-1, alpha-2, alpha-1, pseudotheta. The zeta gene produces hemoglobin in the embryo; alpha-2 and alpha-1 produce hemoglobin in the fetus and adult. The beta-globin locus is located on chromosome 11. The order of the genes in the beta-globin cluster is epsilon, gamma-G, gamma-A, pseudobeta, delta, beta. Epsilon produces hemoglobin in the embryo, and gamma-G and gamma-A produce hemoglobin in the fetus. Delta and beta produce hemoglobin in the adult. What is the most likely mechanism for a gene sequence moving from one chromosome to another