Genetic evidence for unequal effective population sizes of human females and males

Jason A Wilder, Zahra Mobasher, Michael F. Hammer

Research output: Contribution to journalArticle

67 Citations (Scopus)

Abstract

The time to the most recent common ancestor (TMRCA) of the human mitochondria (mtDNA) is estimated to be older than that of the nonrecombining portion of the Y chromosome (NRY). Surveys of variation in globally distributed humans typically result in mtDNA TMRCA values just under 200 thousand years ago (kya), whereas those for the NRY range between 46 and 110 kya. A favored hypothesis for this finding is that natural selection has acted on the NRY, leading to a recent selective sweep. An alternate hypothesis is that sex-biased demographic processes are responsible. Here, we re-examine the disparity between NRY and mtDNA TMRCAs using data collected from individual human populations-a sampling strategy that minimizes the confounding influence of population subdivision in global data sets. We survey variation at 782 bp of the mitochondrial cytochrome c oxidase subunit 3 gene as well as at 26.5 kb of noncoding DNA from the NRY in a sample of 25 Khoisan, 24 Mongolians, and 24 Papua New Guineans. Data from both loci in all populations are best described by a model of constant population size, with the exception of Mongolian mtDNA, which appears to be experiencing rapid population growth. Taking these demographic models into account, we estimate the TMRCAs for each locus in each population. A pattern that is remarkably consistent across all three populations is an approximately twofold deeper coalescence for mtDNA than for the NRY. The oldest TMRCAs are observed for the Khoisan (73.6 kya for the NRY and 176.5 kya for mtDNA), whereas those in the non-African populations are consistently lower (averaging 47.7 kya for the NRY and 92.8 kya for mtDNA). Our data do not suggest that differential natural selection is the cause of this difference in TMRCAs. Rather, these results are most consistent with a higher female effective population size.

Original languageEnglish (US)
Pages (from-to)2047-2057
Number of pages11
JournalMolecular Biology and Evolution
Volume21
Issue number11
DOIs
StatePublished - Nov 2004
Externally publishedYes

Fingerprint

effective population size
Population Density
Mitochondrial DNA
mitochondrial DNA
population size
common ancestry
natural selection
Population
mitochondrion
coalescence
Genetic Selection
cytochrome
chromosome
population growth
ancestry
demographic statistics
DNA
Demography
gene
sampling

Keywords

  • mtDNA
  • Natural selection
  • TMRCA
  • Y chromosome

ASJC Scopus subject areas

  • Genetics
  • Biochemistry
  • Genetics(clinical)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Ecology, Evolution, Behavior and Systematics
  • Agricultural and Biological Sciences (miscellaneous)
  • Molecular Biology

Cite this

Genetic evidence for unequal effective population sizes of human females and males. / Wilder, Jason A; Mobasher, Zahra; Hammer, Michael F.

In: Molecular Biology and Evolution, Vol. 21, No. 11, 11.2004, p. 2047-2057.

Research output: Contribution to journalArticle

Wilder, Jason A ; Mobasher, Zahra ; Hammer, Michael F. / Genetic evidence for unequal effective population sizes of human females and males. In: Molecular Biology and Evolution. 2004 ; Vol. 21, No. 11. pp. 2047-2057.
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