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Published on: February 26, 2016
Gene conversion and natural selection in the evolution of X-linked color vision genes in higher primates
1Human Genetics Center, University of Texas Health Science Center, Houston 77225, USA. li@hgc.sph.uth.tmc.edu
Abstract:
During higher primate evolution, gene conversion seems to have occurred often between the red and green photo-pigment genes, which are tandemly linked on the X chromosome. To understand this phenomenon better, intron 4 sequences of the red and green pigment genes of a male human (an Asian Indian), a male chimpanzee, and a male baboon were amplified by PCR and sequenced. The data show that the intron 4 sequences between the two genes have been strongly or completely homogenized in the three species studied. Apparently recent gene conversion events have occurred in introns 4 of the red and green pigment genes in humans and chimpanzees. Two or more conversion events may have occurred at different times in introns 4 of the two pigment genes in baboons. The divergence between the two genes is significantly lower in intron 4 than in exons 4 and 5 in each species, contrary to the usual situation that introns evolve faster than exons. It is most likely that strong natural selection for maintaining the distinct functions of exons 4 and 5 of the red and green pigment genes has acted against sequence homogenization of these exons.
Related Concept Videos
Epistasis
X-linked Traits
Gene Conversion
X-linked Traits
Gene Duplication and Divergence
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
Gene Conversion

