On Lateral Gene Transfer

• Main Author: Lester, Leo
• Published: University of Reading 2006
• Subjects: 576.58
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487489

Is bacterial evolution phylogenetic or reticulate? Darwin showed that life's history W;J.S mappable with trees. For almost everytfillg that we can see about us, this is largely correct, but beyond the limit of our sight thrives the unseen majority: The tiny, singlecelled prokaryotes do not reserve their genes only for the next generation. Through lateral gene transfer they swap genes with contemporaries, regardless of species. Discovered in the war years, the true place of lateral gene transfer within evolution has not yet been settled. As work on it.has multiplied, so its apparent extent has grown. Here a reappraisal of lateral gene transfer is carried out. The methods of its detection are examined and refined. The ~sults show that lateral transfer is not nearly so prevalent as some say. Less frequent, but still important, lateral gene transfer is shown to be a key mover in the evolution of the entire eukaryote domain. Its effect on individual genes, how it can increase rates of evolution and even trigger 'positive selection regimes, is exposed. The interconnectivity of species is then explored. Species that are the source of many genes receive many. Species that receive lots of genes through lateral transfer hold fewer unique genes. In addition, it is as if all species are connected through a massive network of lateral transfers. But any new information must be placed in its proper context: lateral gene transfer is only one of evolution's tools. Convergent evolution is exposed as a problem, both when trying to detect lateral transfer and perhaps also when constructing phylogenies. For all our problems with bacterial phylogenies, with building and interpreting them, the lesson of lateral gene transfer is that we can have faith in the idea of bacterial species and, after almost a hundred and fifty years, in Darwin too.