The Role of Haplotype Complementation and Purifying Selection in the Genome Evolution

Abstract

<jats:p>We discuss two different ways of evolution for chromosomes and genomes. Purifying selection dominates in large panmictic populations, where the Mendelian law of independent gene assortment is valid. If instead the populations are small, recombination processes are not effective enough to ensure an independent assortment of linked genes, and larger clusters of genes could be inherited as genetic units. There are whole clusters of genes which tend to complement in such conditions instead of single pairs of alleles like in the case of purifying selection. Computer simulations have shown that switching between complementation and purification strategies has the characteristic of a phase transition. This is also responsible for specific distribution of recombination events observed along eukaryotic chromosomes (a higher recombination rate is observed in subtelomeric regions than in central parts of chromosomes) and for sympatric speciation.</jats:p>

Distribution of Recombination Hotspots in the Human Genome – A Comparison of Computer Simulations with Real Data

“…This is in agreement with the view that humans have evolved in relatively small populations [39], [52], in which the formation of linked genes is preferred [38]–[40], [51]. If we consider this problem from the point of evolutionary costs, it seems that avoiding recombination in a region of linked genes is more effective than elimination of recombinants from the population [38], [53]. Interestingly, the majority of hotspots detected by sperm typing (i.e.…”

“…(i) the symmetrical distribution of recombination events around the middle of chromosome [38]–[40], [51], [53], (ii) higher recombination rate in subtelomeric regions, and (iii) highly dynamic generation of recombination hotspots with their very frequent relocation in the chromosome. The distribution of recombination events is related to the distribution of defective alleles along chromosomes.…”