Considerable evidence suggests gene duplication via genome duplication marked early vertebrate evolution, as exemplified by the Hox clusters [37].
However, gene structural analysis reveals evidence of gene duplication and considerable diversity of T4SS components in strains infecting different animals.
For many of the virs, phylogenetic trees position A. phagocytophilum strains infecting ruminants in the U.S. and Europe distant from strains infecting humans and dogs in the U.S. Our study reveals evidence of gene duplication and considerable diversity of T4SS components in strains infecting different animals.
Gene divergence often follows gene duplication.
The two G. raimondii PDCD4 homologs in the MAT5/6/7 subgroup exhibit considerable similarity, suggesting a relatively recent gene duplication event that produced these paralogs.
The large and the small subunit of AGPase in plants exhibit considerable sequence identity [ 1, 2] and they reflect a gene duplication that occurred prior to the divergence of land plants and green algae.
However, by demonstrating considerable gene retention and structural divergence, this study has established that the duplication made a significant contribution to the genomic repertoire of T. brucei, relative to other trypanosomatids, and was a seminal development in its genomic evolution.
However, the considerable similarity of the two PDCD4 homologs in P. patens suggests that gene duplication occurred relatively recently in this species.
There are at least four major mechanisms to produce duplicate genes: (1) genome duplication, (2) tandem gene duplication, (3) segmental duplication and (4) transpositional duplication [31].
