title: The distribution of genotypes of the trypanosome parasite, Crithidia bombi, in populations of its host, Bombus terrestris.
abstract: This study reports the distribution of parasite genotypes for the trypanosome Crithidia bombi across individual units (the colonies) in host populations of a social insect, the bumble bee Bombus terrestris. A number of microsatellite primers were developed and several of them were found to be polymorphic in our samples. Furthermore, a simple algorithm was used to identify the likely multi-locus genotypes present in multiply infected host individuals. The results demonstrated a remarkably high degree of genetic diversity among infections. A first sample from 1997 could only use a low resolution with 2 loci and showed a total of 11 different genotypes of C. bombi from 12 colonies. The sample from 2000 was analysed at 6 polymorphic loci and contained data from 8 colonies that were infected by 27 different C. bombi genotypes. Roughly 16% of all individual bees but half of all colonies (2000 sample) were infected with more than 1 genotype. The infections in the different colonies were also genetically distinct from each other, and the parasite population as a whole was in linkage disequilibrium and deviated from Hardy-Weinberg expectations. The highly structured and genetically diversified population of C. bombi is likely to result from strong genotypic host-parasite interactions.
authors.affiliation: ETH Zurich, Ecology and Evolution, ETH-Zentrum NW, CH-8092 Zurich, Switzerland. psh@env.ethz.ch
authors.forename: P
authors.initials: P
authors.lastname: Schmid-Hempel
authors.forename: C
authors.initials: C
authors.lastname: Reber Funk
mesh_terms: D000465:Algorithms; D000483:Alleles; D000818:Animals; D001483:Base Sequence; D001516:Bees / Q000469:parasitology*; D003421:Crithidia / Q000235:genetics*; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D006790:Host-Parasite Interactions; D015810:Linkage Disequilibrium / Q000235:genetics; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D013557:Switzerland
chemical_list: D016054:DNA, Protozoan