A comparison of the variability spectra of two genomic loci in a European group of individuals reveals fundamental differences pointing to selection or a population bottleneck.
Knowledge about the variability spectra of neutrally evolving sequences in a population is a prerequisite for the identification of genes, which may have been under positive selection during recent human evolution. Here, we report the results of a re-sequencing project of a presumably neutrally evolving chromosome 22 locus with a severely reduced recombination frequency in a group of 24 individuals of German origin. The comparison of these data with the results of a similar analysis of a chromosome 17 locus revealed striking differences, although the same group of individuals was used. For the chromosome 17 locus two well-separated groups of sequences, a positive value of Tajima's D and a TMRCA of 700,000 years were observed. In contrast, the sequences from the chromosome 22 locus were found to be relatively homogeneous, with no deep splits between subgroups; the obtained value for Tajima's D was negative and the TMRCA was only 260,000 years. These discrepancies may be explained by selection or demographic processes. 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.
Schmegner
C
C
Institut für Humangenetik, Universität Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany.
Hoegel
J
J
Vogel
W
W
Assum
G
G
D002886:Chromosomes, Human, Pair 17 / Q000235:genetics; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics; D004247:DNA / Q000235:genetics; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population; D005858:Germany; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium; D008957:Models, Genetic; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D012641:Selection, Genetic; D044465:White People / Q000235:genetics
D004247:DNA