Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Aug;20(16):3484-90.
doi: 10.1111/j.1365-294X.2011.05179.x. Epub 2011 Jul 18.

Niche Segregation and Genetic Structure of Campylobacter Jejuni Populations From Wild and Agricultural Host Species

Affiliations
Free PMC article

Niche Segregation and Genetic Structure of Campylobacter Jejuni Populations From Wild and Agricultural Host Species

Samuel K Sheppard et al. Mol Ecol. .
Free PMC article

Abstract

Bacterial populations can display high levels of genetic structuring but the forces that influence this are incompletely understood. Here, by combining modelling approaches with multilocus sequence data for the zoonotic pathogen Campylobacter, we investigated how ecological factors such as niche (host) separation relate to population structure. We analysed seven housekeeping genes from published C. jejuni and C. coli isolate collections from a range of food and wild animal sources as well as abiotic environments. By reconstructing genetic structure and the patterns of ancestry, we quantified C. jejuni host association, inferred ancestral populations, investigated genetic admixture in different hosts and determined the host origin of recombinant C. jejuni alleles found in hybrid C. coli lineages. Phylogenetically distinct C. jejuni lineages were associated with phylogenetically distinct wild birds. However, in the farm environment, phylogenetically distant host animals shared several C. jejuni lineages that could not be segregated according to host origin using these analyses. Furthermore, of the introgressed C. jejuni alleles found in C. coli lineages, 73% were attributed to genotypes associated with food animals. Our results are consistent with an evolutionary scenario where distinct Campylobacter lineages are associated with different host species but the ecological factors that maintain this are different in domestic animals such that phylogenetically distant animals can harbour closely related strains.

Figures

Fig. 1
Fig. 1. Genealogical tree of C. jejuni and lineage association with host.
(a) Clonalframe genealogy of C. jejuni STs of isolates from published data sets. The source of isolates is indicated by colour for STs from chickens (red), ruminants (blue), chicken and ruminants together (grey), ducks and geese (yellow), gulls (light blue), pigeons and doves (brown) and passerines (purple). Isolates from pheasants, unidentified birds and the environment were not included on the tree. Open circles indicate STs found in both a farm animal and wild bird host. The dominant clonal complex and Baps cluster (in brackets) associated with each clade is indicated. The scale bar gives the genetic distance in coalescent units. (b) Comparison of a measure of association between lineages (clades) and isolate source species observed with that expected by chance in C. jejuni from chickens, ruminants, ducks and geese, pigeons and doves, gulls, and passerines. Arrows indicate the observed measure of association, and histograms are the range of results from 10 000 random permutations of the data set.
Fig. 2
Fig. 2. Genetic structure of C. jejuni genotypes from different host groups.
Each bacterial isolate is represented by a vertical bar, showing the probability that it originates from each of the putative group defined using Baps. The sources associated with each BAPS cluster are indicated by different colours. If each host/niche group had a genetically distinct population with no admixture between sources, then the charts would be uniform in colour for chicken (red), ruminants (blue), the environment (green), ducks and geese (yellow), gulls (light blue), pigeons and doves (brown) and passerine birds (purple). Isolates coloured grey represent farm types that are associated with both chicken and ruminant sources. Pheasants and unidentified birds were not included.
Fig. 3
Fig. 3. Origin of interspecies recombinant alleles.
Alleles from hybrid STs (n = 48) were assigned to host-associated Baps cluster origin populations using Brat. Each isolate is represented by a vertical bar, showing the estimated probability that it originates from each of the putative sources indicated by different colours. Two independent analyses were carried out assigning hybrid alleles to (a) farm (formula image) and non-farm(formula image), and (b) chicken (formula image) and ruminant (formula image). An equal area of each colour would be expected in the absence of genetic differentiation by host association.

Similar articles

See all similar articles

Cited by 44 articles

See all "Cited by" articles

Publication types

MeSH terms

Feedback