Gene Families and Evolution

Abstract

Gene families refer to two or more genes that come from a common ancestral gene in which the individual members of the gene family may or may not have a similar function. The idea of gene families implicitly invokes a process in which an original gene exists, is duplicated and the resulting gene products evolve. The most common result of gene duplication is that mutation renders one of the products nonfunctional and in the absence of conserving natural selection, one of the members becomes no longer recognizable. Gene families may be clustered or dispersed and may exchange with each other through the mechanisms of gene conversion or unequal crossover. Therefore understanding the processes of molecular evolution are essential to understanding what gene families are, where they came from and what their function might be. In a sense, duplicate genes allow for more evolutionary potential. At first glance this could be beneficial; if one gene incurred a lethal mutation the other gene simply takes over, there is some protection from mutation based on redundancy. Having two identical genes could result in twice as much product; this may or may not be beneficial in a cell where the integration of thousands of gene products must be coordinated and slight concentration differences can alter biochemical pathways.