The following data represent short DNA sequences from five species: human, chimpanzee, gorilla, orangutan, and baboon. The sequences are each 50 bp long. They represent a short piece of a gene for testis-specific protein Y, located on the Y chromosome. The complete human sequence is given; the sequences for the other four species are shown only where they differ from the human sequence. Calculate the genetic difference between each pair of species. (For example, chimps and gorillas differ from each other in 2 out of 50 bases, or 4 percent; thus, the genetic difference between chimps and gorillas is 0.04.) Then use UPGMA to reconstruct the phylogeny for these five species. Is your phylogeny consistent with those shown in 28–18?
