Evolution and survival on eutherian sex chromosomes

Melissa Wilson Sayres, Kateryna D. Makova

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

Since the two eutherian sex chromosomes diverged from an ancestral autosomal pair, the X has remained relatively generich, while the Y has lost most of its genes through the accumulation of deleterious mutations in nonrecombining regions. Presently, it is unclear what is distinctive about genes that remain on the Y chromosome, when the sex chromosomes acquired their unique evolutionary rates, and whether X-Y gene divergence paralleled that of paralogs located on autosomes. To tackle these questions, here we juxtaposed the evolution of X and Y homologous genes (gametologs) in eutherian mammals with their autosomal orthologs in marsupial and monotreme mammals. We discovered that genes on the X and Y acquired distinct evolutionary rates immediately following the suppression of recombination between the two sex chromosomes. The Y-linked genes evolved at higher rates, while the X-linked genes maintained the lower evolutionary rates of the ancestral autosomal genes. These distinct rates have been maintained throughout the evolution of X and Y. Specifically, in humans, most X gametologs and, curiously, also most Y gametologs evolved under stronger purifying selection than similarly aged autosomal paralogs. Finally, after evaluating the current experimental data from the literature, we concluded that unique mRNA/protein expression patterns and functions acquired by Y (versus X) gametologs likely contributed to their retention. Our results also suggest that either the boundary between sex chromosome strata 3 and 4 should be shifted or that stratum 3 should be divided into two strata.

Original languageEnglish (US)
Article numbere1000568
JournalPLoS Genetics
Volume5
Issue number7
DOIs
StatePublished - Jul 2009
Externally publishedYes

Fingerprint

Sex Chromosomes
sex chromosomes
chromosome
Survival
gene
Genes
genes
Mammals
Y-Linked Genes
Marsupialia
X-Linked Genes
Chromosomes, Human, Pair 4
Chromosomes, Human, Pair 3
mammal
Y Chromosome
monotreme
mammals
Genetic Recombination
marsupial
autosomes

ASJC Scopus subject areas

  • Genetics
  • Molecular Biology
  • Ecology, Evolution, Behavior and Systematics
  • Cancer Research
  • Genetics(clinical)

Cite this

Evolution and survival on eutherian sex chromosomes. / Wilson Sayres, Melissa; Makova, Kateryna D.

In: PLoS Genetics, Vol. 5, No. 7, e1000568, 07.2009.

Research output: Contribution to journalArticle

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