Mittwoch, 24. Januar 2007

Population bottleneck during "out of africa"

New hints for a population bottleneck concerning (anatomical modern) humans leaving the african continent were presented in "Annals of Human Genetics":

"... At the NF1 gene locus two clearly separated groups of haplotypes, corresponding to the two haplogroups described by us (Schmegner et al. 2005), are present in the European population and both Asian populations, but not in the African population. This argues against a population bottleneck during the immigration of the AMH into Europe, because a reduction to two NF1 gene lineages during this event would not have affected the Asian populations. At the chromosome 22 locus a different picture is obtained for the European and Asian populations, with no split into two clearly separated subgroups of haplotypes. The patterns for the two loci in the African population are quite similar. Therefore, if a population bottleneck is considered to explain the variability patterns, the HapMap data show that this bottleneck most probably occurred throughout the emigration of the AMH out of Africa. Recently signs of a population bottleneck in variability data obtained for a number of genomic loci in European and Asian populations, but not in African populations, were described and also led to the conclusion that this bottleneck occurred after the appearance of the AMH in Africa, and thus presumably during the emigration out of Africa (Harpending & Rogers, 2000; Balciuniene et al. 2001; Alonso & Armour, 2004; Marth et al. 2004; Stajich & Hahn, 2005; Voight et al. 2005)."
And for Europe only:
"Regarding demography, the most plausible explanation is the assumption of a severe bottleneck in the history of the European population: in the case of the chromosome 17 locus two ancient lineages passed this bottleneck; for the chromosome 22 locus it was only one ancient lineage."

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