Abstract
In order to identify the functional characteristics of genomes, it is necessary to understand the different forces that govern their evolution. Until recently, only three processes were considered : mutation, drift and selection. However, in recent years, numerous observations have shown that a fourth force has a major impact on the evolution of genomes: biased gene conversion to GC (gBGC). This process is linked to recombination, and tends to favor the fixation of G or C alleles over A or T alleles. This phenomenon is at the origin of the very particular genomic landscapes observed in vertebrates (the isochores). It is essential to take this gBGC process into account, as in many respects it can be confused with natural selection. Laurent Duret presented an analysis of gBGC signatures in the tree of life. These results indicate that gBGC affects many lineages, not only in eukaryotes but also in bacteria.
