The origin of new genes: glimpses from the young and old

Top Cited Papers
Publisher Website
Google Scholar
Abstract
The variation in the numbers of genes in different organisms indicates a general process of the origin and evolution of new genes. Examining young genes is a direct approach to study this process, whereas ancient genes reveal the antiquity of some origination mechanisms. Several molecular mechanisms are involved in the creation of new gene structure, among which exon shuffling, retroposition and gene duplication have been found to be particularly important. A new gene in its early stage usually undergoes rapid changes in sequence, structure and expression, which indicates a continuous evolution of function. A significant role of positive Darwinian selection has been detected underlying these changes and adaptive evolution might have directed the entire origination process of new genes. Direct and indirect observations of new genes in eukaryotic genomes show that genes with new functions are not as rare as was previously thought. Analysis of the repeated new gene origination by retroposition in the Drosophila genome has uncovered a pattern in which new genes tend to avoid the X-chromosome linkage and most of the X-chromosome-derived autosomal new genes have evolved male-specific functions. This points to the importance of genome position in new gene origination.