Sex-biased evolutionary forces shape genomic patterns of human diversity

Michael F Hammer, Fernando L. Mendez, Murray P. Cox, August E. Woerner, Jeffrey D. Wall

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

Comparisons of levels of variability on the autosomes and X chromosome can be used to test hypotheses about factors influencing patterns of genomic variation. While a tremendous amount of nucleotide sequence data from across the genome is now available for multiple human populations, there has been no systematic effort to examine relative levels of neutral polymorphism on the X chromosome versus autosomes. We analyzed ∼210 kb of DNA sequencing data representing 40 independent noncoding regions on the autosomes and X chromosome from each of 90 humans from six geographically diverse populations. We correct for differences in mutation rates between males and females by considering the ratio of within-human diversity to human-orangutan divergence. We find that relative levels of genetic variation are higher than expected on the X chromosome in all six human populations. We test a number of alternative hypotheses to explain the excess polymorphism on the X chromosome, including models of background selection, changes in population size, and sex-specific migration in a structured population. While each of these processes may have a small effect on the relative ratio of X-linked to autosomal diversity, our results point to a systematic difference between the sexes in the variance in reproductive success; namely, the widespread effects of polygyny in human populations. We conclude that factors leading to a lower male versus female effective population size must be considered as important demographic variables in efforts to construct models of human demographic history and for understanding the forces shaping patterns of human genomic variability.

Original languageEnglish (US)
Article numbere1000202
JournalPLoS Genetics
Volume4
Issue number9
DOIs
StatePublished - Sep 2008

Fingerprint

X chromosome
chromosome
genomics
autosomes
X Chromosome
gender
human population
polymorphism
population size
demographic statistics
genetic polymorphism
Population
Population Density
polygyny
demographic history
Pongo pygmaeus
effective population size
Demography
Pongo
reproductive success

ASJC Scopus subject areas

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

Cite this

Sex-biased evolutionary forces shape genomic patterns of human diversity. / Hammer, Michael F; Mendez, Fernando L.; Cox, Murray P.; Woerner, August E.; Wall, Jeffrey D.

In: PLoS Genetics, Vol. 4, No. 9, e1000202, 09.2008.

Research output: Contribution to journalArticle

Hammer, Michael F ; Mendez, Fernando L. ; Cox, Murray P. ; Woerner, August E. ; Wall, Jeffrey D. / Sex-biased evolutionary forces shape genomic patterns of human diversity. In: PLoS Genetics. 2008 ; Vol. 4, No. 9.
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