Genetic relationships and spatial genetic structure among clonal stocks ofTrypanosoma cruzi in Colombia

Genetic variability in the protozoan causative agent of Chagas' disease, Tr ypanosoma cruzi, has been analysed in some Latin American countries; Brazil , Bolivia, Chile and Paraguay. Although Colombia is a country displaying en ormous biological diversity, few studies have been conducted from the persp ective of the population genetics of Trypanosoma cruzi. This study was carr ied out using 23 Colombian stocks of this protozoan, analysed for 13 isoenz yme loci. The main population genetic results were: (1) Colombia is one of the distribution areas where T. cruzi appears to have the highest genetic v ariability and heterogeneity in Latin America; (2) the Pgm locus was found in fixed heterozygosis, supporting the presence of diploidy in this organis m; (3) the absence of segregating genotypes and the absence of Hardy-Weinbe rg equilibrium support the view of the existence of a clonal structure as c laimed by Tibayrenc and Ayala. Nevertheless, one characteristic of clonal s tructure, that of over-representation of some identical zymodemes in vast a reas of varying environmental conditions, was not found in Colombia. In thi s country, a strong spatial autocorrelation, with a classic structure of re gional patches, was observed.