title: Recent changes in phenotype and patterns of host specialization in Wolbachia bacteria.
abstract: Wolbachia are a genus of bacterial symbionts that are known to manipulate the reproduction of their arthropod hosts, both by distorting the host sex ratio and by inducing cytoplasmic incompatibility. Previous work has suggested that some Wolbachia clades specialize in particular host taxa, but others are diverse. Furthermore, the frequency with which related strains change in phenotype is unknown. We have examined these issues for Wolbachia bacteria from Acraea butterflies, where different interactions are known in different host species. We found that bacteria from Acraea butterflies mostly cluster together in several different clades on the bacterial phylogeny, implying specialization of particular strains on these host taxa. We also observed that bacterial strains with different phenotypic effects on their hosts commonly shared identical gene sequences at two different loci. This suggests both that the phenotypes of the strains have changed recently between sex ratio distortion and cytoplasmic incompatibility, and that host specialization is not related to the bacterial phenotype, as suggested from previous data. We also analysed published data from other arthropod taxa, and found that the Wolbachia infections of the majority of arthropod genera tend to cluster together on the bacterial phylogeny. Therefore, we conclude that Wolbachia is most likely to move horizontally between closely related hosts, perhaps because of a combination of shared vectors for transmission and physiological specialization of the bacteria on those hosts.
authors.affiliation: Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, Department of Biology, University College London, 4 Stephenson Way, London, NW1 2HE, UK. fmj1001@mole.bio.cam.ac.uk
authors.forename: Francis M
authors.initials: FM
authors.lastname: Jiggins
authors.forename: Joanna K
authors.initials: JK
authors.lastname: Bentley
authors.forename: Michael E N
authors.initials: ME
authors.lastname: Majerus
authors.forename: Gregory D D
authors.initials: GD
authors.lastname: Hurst
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D002080:Butterflies / Q000382:microbiology*; D018833:Chaperonins; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D012737:Sex Factors; D013559:Symbiosis; D020577:Wolbachia / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C028715:GroE protein, E coli; D006360:Heat-Shock Proteins; C112171:Wsp protein, Wolbachia; D018833:Chaperonins