Open AccessBacterial Evolution Through the Selective Loss of Beneficial Genes: Trade-Offs in Expression Involving Two Loci
Author(s) -
Erik R. Zinser,
Dominique Schneider,
Michel Blot,
Roberto Kolter
Publication year - 2003
Publication title -
genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.792
H-Index - 246
eISSN - 1943-2631
pISSN - 0016-6731
DOI - 10.1093/genetics/164.4.1271
Subject(s) - biology , gene , genetics , pleiotropy , mutation , gene expression , mechanism (biology) , regulation of gene expression , selection (genetic algorithm) , genetic drift , homologous recombination , negative selection , gene pool , phenotype , genetic variation , population , genome , philosophy , demography , epistemology , artificial intelligence , sociology , computer science , genetic diversity
The loss of preexisting genes or gene activities during evolution is a major mechanism of ecological specialization. Evolutionary processes that can account for gene loss or inactivation have so far been restricted to one of two mechanisms: direct selection for the loss of gene activities that are disadvantageous under the conditions of selection (i.e., antagonistic pleiotropy) and selection-independent genetic drift of neutral (or nearly neutral) mutations (i.e., mutation accumulation). In this study we demonstrate with an evolved strain of Escherichia coli that a third, distinct mechanism exists by which gene activities can be lost. This selection-dependent mechanism involves the expropriation of one gene's upstream regulatory element by a second gene via a homologous recombination event. Resulting from this genetic exchange is the activation of the second gene and a concomitant inactivation of the first gene. This gene-for-gene expression tradeoff provides a net fitness gain, even if the forfeited activity of the first gene can play a positive role in fitness under the conditions of selection.