Gorilla and orangutan c-myc nucleotide sequences: inference on hominoid phylogeny

The nucleotide sequences of the gorilla and orangutan myc loci have been determined by the dideoxy nucleotide method. As previously observed in the human and chimpanzee sequences, an open reading frame (ORF) of 188 codons overlapping exon 1 could be deduced from the gorilla sequence. However, no such ORF appeared in the orangutan sequence. The two sequences were aligned with those of human and chimpanzee as hominoids and of gibbon and marmoset as outgroups of hominoids. The branching order in the evolution of primates was inferred from these data by different methods: maximum parsimony and neighbor-joining. Our results support the view that the gorilla lineage branched off before the human and chimpanzee diverged and strengthen the hypothesis that chimpanzee and gorilla are more related to human than is orangutan.