Methods for detecting horizontal transfer of genes

Abstract

Horizontal gene transfers are events that have no eyewitnesses; therefore, inferences regarding the nature and even existence of transfer events rely solely upon circumstantial evidence. Two general approaches have been taken to identify genes having participated in gene exchange: either examining the evolutionary history of a gene within its phylogenetic context and equating an incongruity with a transfer or examining the sequence composition of a gene within its genomic context and attributing incongruity with differential history. In both cases, discordance can arise from sources aside from gene transfer, and the degree of the discordance can provide some measure of confidence that a transfer has occurred.