title: Genomic changes following host restriction in bacteria.
abstract: Many genomic sequences have been recently published for bacteria that can replicate only within eukaryotic hosts. Comparisons of genomic features with those of closely related bacteria retaining free-living stages indicate that rapid evolutionary change often occurs immediately after host restriction. Typical changes include a large increase in the frequency of mobile elements in the genome, chromosomal rearrangements mediated by recombination among these elements, pseudogene formation, and deletions of varying size. In anciently host-restricted lineages, the frequency of insertion sequence elements decreases as genomes become extremely small and strictly clonal. These changes represent a general syndrome of genome evolution, which is observed repeatedly in host-restricted lineages from numerous phylogenetic groups. Considerable variation also exists, however, in part reflecting unstudied aspects of the population structure and ecology of host-restricted bacterial lineages.
authors.affiliation: Department of Ecology and Evolutionary Biology & Center for Insect Science, University of Arizona, Tucson, AZ 85721, USA. nmoran@email.arizona.edu
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Moran
authors.forename: Gordon R
authors.initials: GR
authors.lastname: Plague
mesh_terms: D001419:Bacteria; D019143:Evolution, Molecular; D005798:Genes, Bacterial / Q000502:physiology*; D014644:Genetic Variation; D016680:Genome, Bacterial