Inter- and intraspecies phylogenetic analyses reveal extensive X-Y gene conversion in the evolution of gametologous sequences of human sex chromosomes

It has long been believed that the male-specific region of the human Y chromosome (MSY) is genetically independent from the X chromosome. This idea has been recently dismissed due to the discovery that X-Y gametologous gene conversion may occur. However, the pervasiveness of this molecular process i...

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Bibliographic Details
Published in:Molecular biology and evolution 2014-08, Vol.31 (8), p.2108-2123
Main Authors: Trombetta, Beniamino, Sellitto, Daniele, Scozzari, Rosaria, Cruciani, Fulvio
Format: Article
Language:English
Subjects:
Animals
Chromosomes
Chromosomes, Human, X
Chromosomes, Human, X - genetics
Chromosomes, Human, Y
Chromosomes, Human, Y - genetics
Comparative analysis
Discoveries
Evolution
Evolution, Molecular
Female
Gene Conversion
Genetics
Haplotypes
Humans
Life Sciences
Male
Pan troglodytes
Pan troglodytes - genetics
Phylogenetics
Phylogeny
Polymorphism
Polymorphism, Single Nucleotide
Sequence Analysis, DNA
X Chromosome
X Chromosome - genetics
Y Chromosome
Y Chromosome - genetics
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Summary:It has long been believed that the male-specific region of the human Y chromosome (MSY) is genetically independent from the X chromosome. This idea has been recently dismissed due to the discovery that X-Y gametologous gene conversion may occur. However, the pervasiveness of this molecular process in the evolution of sex chromosomes has yet to be exhaustively analyzed. In this study, we explored how pervasive X-Y gene conversion has been during the evolution of the youngest stratum of the human sex chromosomes. By comparing about 0.5 Mb of human-chimpanzee gametologous sequences, we identified 19 regions in which extensive gene conversion has occurred. From our analysis, two major features of these emerged: 1) Several of them are evolutionarily conserved between the two species and 2) almost all of the 19 hotspots overlap with regions where X-Y crossing-over has been previously reported to be involved in sex reversal. Furthermore, in order to explore the dynamics of X-Y gametologous conversion in recent human evolution, we resequenced these 19 hotspots in 68 widely divergent Y haplogroups and used publicly available single nucleotide polymorphism data for the X chromosome. We found that at least ten hotspots are still active in humans. Hence, the results of the interspecific analysis are consistent with the hypothesis of widespread reticulate evolution within gametologous sequences in the differentiation of hominini sex chromosomes. In turn, intraspecific analysis demonstrates that X-Y gene conversion may modulate human sex-chromosome-sequence evolution to a greater extent than previously thought.
ISSN:0737-4038
1537-1719
DOI:10.1093/molbev/msu155