Genetic evidence for a higher female migration rate in humans.
Mitochondrial DNA and the Y chromosome have been used extensively in the study of modern human origins and other phylogenetic questions, but not in the context of their sex-specific modes of transmission. mtDNA is transmitted exclusively by females, whereas the Y chromosome is passed only among males. As a result, differences in the reproductive output or migration rate of males and females will influence the geographic patterns and relative level of genetic diversity on the Y chromosome, autosomes and mtDNA (ref. 1). We have found that Y chromosome variants tend to be more localized geographically than those of mtDNA and the autosomes. The fraction of variation within human populations for Y chromosome single nucleotide polymorphisms (SNPs) is 35.5%, versus 80-85% for the autosomes and mtDNA (refs 6-8). A higher female than male migration rate (via patrilocality, the tendency for a wife to move into her husband's natal household) explains most of this discrepancy, because diverse Y chromosomes would enter a population at a lower rate than mtDNA or the autosomes. Polygyny may also contribute, but the reduction of variation within populations that we measure for the Y chromosome, relative to the autosomes and mitochondrial DNA, is of such magnitude that differences in the effective population sizes of the sexes alone are insufficient to produce the observation.
Seielstad
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Program for Population Genetics, Harvard School of Public Health, Boston, Massachusetts 02115, USA. mark@ppg.harvard.edu
Minch
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Cavalli-Sforza
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D004272:DNA, Mitochondrial / Q000235:genetics; D004641:Emigration and Immigration; D005260:Female; D014644:Genetic Variation; D005828:Genetics, Population; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D011110:Polymorphism, Genetic; D012727:Sex Characteristics; D014998:Y Chromosome / Q000235:genetics
D004272:DNA, Mitochondrial