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The Impact of Recombination on Nucleotide Substitutions in the Human Genome

Summary: The Impact of Recombination on Nucleotide
Substitutions in the Human Genome
Laurent Duret1
*, Peter F. Arndt2
1 Laboratoire de Biome´trie et Biologie Evolutive, Universite´ de Lyon, Universite´ Lyon 1, CNRS, UMR 5558, Villeurbanne, France, 2 Department for Computational Molecular
Biology, Max Planck Institute for Molecular Genetics, Berlin, Germany
Unraveling the evolutionary forces responsible for variations of neutral substitution patterns among taxa or along genomes
is a major issue for detecting selection within sequences. Mammalian genomes show large-scale regional variations of GC-
content (the isochores), but the substitution processes at the origin of this structure are poorly understood. We analyzed the
pattern of neutral substitutions in 1 Gb of primate non-coding regions. We show that the GC-content toward which
sequences are evolving is strongly negatively correlated to the distance to telomeres and positively correlated to the rate of
crossovers (R2
= 47%). This demonstrates that recombination has a major impact on substitution patterns in human, driving
the evolution of GC-content. The evolution of GC-content correlates much more strongly with male than with female
crossover rate, which rules out selectionist models for the evolution of isochores. This effect of recombination is most
probably a consequence of the neutral process of biased gene conversion (BGC) occurring within recombination hotspots.
We show that the predictions of this model fit very well with the observed substitution patterns in the human genome. This
model notably explains the positive correlation between substitution rate and recombination rate. Theoretical calculations


Source: Arndt, Peter - Max-Planck-Institut für molekulare Genetik
Spang, Rainer - Computational Molecular Biology Group, Max-Planck-Institut für molekulare Genetik


Collections: Biology and Medicine; Biotechnology; Computer Technologies and Information Sciences; Physics