The Pattern of New Gene Evolution Shaped by Darwinian Selection

摘要

It is known that a lot of new genes originated and evolved in the genomes of various organisms (Long et al. 2003, Nature Rev Genet; Kaessmann et al. 2009, Nature Rev Genet). Are there any pat-terns or rules associated with these new gene origination events? What are the evolutionary forces responsible for these patterns? The early investigation of the new genes generated via RNA-based duplication revealed a directional movement of genes that are male biased expressed in Drosophila and mammals (Betran et al. 2002, Genome Res; Emerson et al. 2004, Science). The comparison of the chromosomal distribution of the male gene traffics with the mutation distribution, as shown in pseudogenes in mammals, revealed that Darwinian positive selection for new male functions were governing these gene traffics between the X chromosomes and autosomes. We recently found that the directional gene movement as found in the new genes formed via RNA-based duplication were also true of the movement of the new genes generated by the DNA-based duplication, a more general form of duplication (Vibranovsky et al. 2009, Genome Res). The consequence of long term evolu-tion is that most male genes that were biased expressed in male germlines would be accumulated on autosomes, as the microarray experiments confirmed. Two levels of mechanistic processes, the male germline X-inactivation and sex-related population genetic processes, might be involved in the male gene movement.