Table of Contents
International Journal of Evolutionary Biology
Volume 2012, Article ID 394026, 14 pages
Review Article

The Ecology of Bacterial Genes and the Survival of the New

1Unitat Mixta d'Investigació en Genòmica i Salut, Centre Superior d'Investigació en Salut Pública i Institut Cavanilles de Biodiversitat i Biologia Evolutiva, 46020 València, Spain
2School of Natural Sciences, University of California, Merced, CA 95343, USA

Received 21 April 2012; Accepted 26 June 2012

Academic Editor: Frédéric Brunet

Copyright © 2012 M. Pilar Francino. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Much of the observed variation among closely related bacterial genomes is attributable to gains and losses of genes that are acquired horizontally as well as to gene duplications and larger amplifications. The genomic flexibility that results from these mechanisms certainly contributes to the ability of bacteria to survive and adapt in varying environmental challenges. However, the duplicability and transferability of individual genes imply that natural selection should operate, not only at the organismal level, but also at the level of the gene. Genes can be considered semiautonomous entities that possess specific functional niches and evolutionary dynamics. The evolution of bacterial genes should respond both to selective pressures that favor competition, mostly among orthologs or paralogs that may occupy the same functional niches, and cooperation, with the majority of other genes coexisting in a given genome. The relative importance of either type of selection is likely to vary among different types of genes, based on the functional niches they cover and on the tightness of their association with specific organismal lineages. The frequent availability of new functional niches caused by environmental changes and biotic evolution should enable the constant diversification of gene families and the survival of new lineages of genes.