Probing Mixed-Genotype Infections II: High Multiplicity in Natural Infections of the Trypanosomatid,Crithidia bombi,in Its Host,Bombus spp |
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Authors: | Martina Tognazzo Regula Schmid-Hempel Paul Schmid-Hempel |
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Institution: | Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.; University of Leeds, United Kingdom, |
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Abstract: | Mixed-genotype infections have major consequences for many essential elements of host-parasite interactions. With genetic exchange between co-infecting parasite genotypes increased diversity among parasite offspring and the emergence of novel genotypes from infected hosts is possible. We here investigated mixed- genotype infections using the host, Bombus spp. and its trypanosome parasite Crithidia bombi as our study case. The natural infections of C. bombi were genotyped with a novel method for a representative sample of workers and spring queens in Switzerland. We found that around 60% of all infected hosts showed mixed-genotype infections with an average of 2.47±0.22 (S.E.) and 3.65±1.02 genotypes per worker or queen, respectively. Queens, however, harboured up to 29 different genotypes. Based on the genotypes of co-infecting strains, these could be putatively assigned to either ‘primary’ and ‘derived’ genotypes - the latter resulting from genetic exchange among the primary genotypes. High genetic relatedness among co-infecting derived but not primary genotypes supported this scenario. Co-infection in queens seems to be a major driver for the diversity of genotypes circulating in host populations. |
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