The detection of geographical substructuring of Trypanosoma brucei populations by the analysis of minisatellite polymorphisms

Analysis of natural populations of Trypanosoma brucei has shown that there is linkage disequilibrium between alleles at pairs of loci in isolates take n from the field. This disequilibrium can occur as a result of a low freque ncy of genetic exchange, the masking of frequent genetic exchange by the ra pid expansion of a few genotypes or by the treatment of 2 (or more) genetic ally isolated populations as a single population. We have analysed stocks f rom 2 geographically separate locations using 3 minisatellite markers to de termine the frequencies of the alleles in each area and the frequency and n ature of the multilocus genotypes. The results show that many alleles and m ultilocus genotypes are unique to each geographical location, supporting th e conclusion that these populations are genetically isolated with limited o r no gene flow between them. This geographical substructuring needs to be t aken into account in considering the origins of the linkage disequilibrium in a number of populations.