Clonal population structure of Colombian sylvatic Trypanosoma cruzi

Isoenzyme variability and evidence of genetic exchange were evaluated in 75 wild stocks of Trypanosoma cruzi obtained from different hosts from 5 geog raphical regions within the endemic area in Colombia. Cluster analysis of g enetic variability was attempted. Thirty-three multilocus enzyme genotypes (clonets) were identified from 75 stocks, 27 of which clustered with zymode me Z1 and 6 with zymodeme Z3. Two stocks isolated from human infections sho wed the potential risk to rural communities in Colombia. The stocks exhibit ed departures from Hardy-Weinberg expectations, including both fixed hetero zygote and fixed homozygote demes, where both segregation and recombination were absent. To inspect for population subdivision that might falsely impl y clonality in these stocks, Wright's F statistics were calculated. Theta v alues (F-st) were significantly different from 0 when 33 clonets, 27 Z1-lik e clonets, and 5 geographical subpopulations were compared; thus, a signifi cant amount of divergence has occurred between and within them. In addition , linkage disequilibrium was detected for most possible pairwise comparison s of loci. In conclusion, the above results all support a scenario of long- term clonal evolution in Colombian sylvatic T. cruzi populations.