Disentangling hybridization and host colonization in parasitic roundworms of humans and pigs

Charles D. Criscione, Joel D. Anderson, Dan Sudimack, Weidong Peng, Bharat Jha, Sarah Williams-Blangero, Timothy J.C. Anderson

    Research output: Contribution to journalArticlepeer-review

    79 Scopus citations

    Abstract

    Knowledge of cross-transmission and hybridization between parasites of humans and reservoir hosts is critical for understanding the evolution of the parasite and for implementing control programmes. There is now a consensus that populations of pig and human Ascaris (roundworms) show significant genetic subdivision. However, it is unclear whether this has resulted from a single or multiple host shift(s). Furthermore, previous molecular data have not been sufficient to determine whether sympatric populations of human and pig Ascaris can exchange genes. To disentangle patterns of host colonization and hybridization, we used 23 microsatellite loci to conduct Bayesian clustering analyses of individual worms collected from pigs and humans. We observed strong differentiation between populations which was primarily driven by geography, with secondary differentiation resulting from host affiliation within locations. This pattern is consistent with multiple host colonization events. However, there is low support for the short internal branches of the dendrograms. In part, the relationships among clusters may result from current hybridization among sympatric human and pig roundworms. Indeed, congruence in three Bayesian methods indicated that 4 and 7% of roundworms sampled from Guatemala and China, respectively, were hybrids. These results indicate that there is contemporary cross-transmission between populations of human and pig Ascaris.

    Original languageEnglish (US)
    Pages (from-to)2669-2677
    Number of pages9
    JournalProceedings of the Royal Society B: Biological Sciences
    Volume274
    Issue number1626
    DOIs
    StatePublished - Nov 7 2007

    Keywords

    • Ascaris spp.
    • Hybridization
    • Microsatellites
    • Molecular epidemiology
    • Nematode
    • Parasite

    ASJC Scopus subject areas

    • Biochemistry, Genetics and Molecular Biology(all)
    • Immunology and Microbiology(all)
    • Environmental Science(all)
    • Agricultural and Biological Sciences(all)

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