Nucleotide sequence of the beta-globin genes in gorilla and macaque: the origin of nucleotide polymorphisms in human

Abstract

Part of the beta-globin genes of Macaca cynomolgus and Gorilla gorilla has been cloned and sequenced. Ten putatively neutral nucleotide polymorphisms have been described at the beta-globin locus in humans. They are associated in seven combinations, which define seven different haplotypes of the beta-globin gene: four major frameworks--1, 2, 3, and 3--and three minor frameworks, which we term KI1, KA1, and OR1. The nucleotide sequences of these frameworks are compared with those of homologous sequences in chimpanzee, colobus, macaque, and gorilla. This comparison provides strong evidence that framework 2 was the earliest framework in the human lineage. From framework 2, a rooted parsimonious tree for the six other frameworks is constructed. This phylogenetic tree is discussed in terms of the evolution of nucleotide polymorphisms as well as in terms of genetic affinities between human populations. For each position at which there is base difference in comparing human, gorilla, and chimpanzee beta-globin genes, the phyletic lineage where the corresponding substitution occurred has been identified using the maximum parsimony procedure. The data provide evidence that polymorphisms may represent a significant component of differences between closely related species. If so, nucleotide polymorphisms may strongly bias estimates of small evolutionary distances.