Duplication is more common among laterally transferred genes than among indigenous genes.
BACKGROUND
Recent developments in the understanding of paralogous evolution have prompted a focus not only on obviously advantageous genes, but also on genes that can be considered to have a weak or sporadic impact on the survival of the organism. Here we examine the duplicative behavior of a category of genes that can be considered to be mostly transient in the genome, namely laterally transferred genes. Using both a compositional method and a gene-tree approach, we identify a number of proposed laterally transferred genes and study their nucleotide composition and frequency of duplication.


RESULTS
It is found that duplications are significantly overrepresented among potential laterally transferred genes compared to the indigenous ones. Furthermore, the GC3 distribution of potential laterally transferred genes was found to be largely uniform in some genomes, suggesting an import from a broad range of donors.


CONCLUSIONS
The results are discussed not in a context of strongly optimized established genes, but rather of genes with weak or ancillary functions. The importance of duplication may therefore depend on the variability and availability of weak genes for which novel functions may be discovered. Therefore, lateral transfer may accelerate the evolutionary process of duplication by bringing foreign genes that have mainly weak or no function into the genome.
Hooper
Sean D
SD
Department of Molecular Evolution, Uppsala University, Norbyvagen 18C, SE-75236 Uppsala, Sweden. otto.berg@ebc.uu.se
Berg
Otto G
OG
D001407:Bacillus / Q000235:genetics; D001412:Bacillus subtilis / Q000235:genetics; D003013:Clostridium / Q000235:genetics; D003016:Clostridium perfringens / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D019453:Escherichia coli O157 / Q000235:genetics; D019143:Evolution, Molecular; D020862:GC Rich Sequence / Q000235:genetics; D020440:Gene Duplication; D022761:Gene Transfer, Horizontal / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics*; D016680:Genome, Bacterial; D007711:Klebsiella pneumoniae / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000235:genetics; D012486:Salmonella typhimurium / Q000235:genetics; D012763:Shigella flexneri / Q000235:genetics; D013211:Staphylococcus aureus / Q000235:genetics