Analysis of helminth genetic data: comparative examples with Haemonchus contortus isozymes using exact tests or resampling procedures

Population genetic data on helminths are scarce and it is important to fine tune analyses of these data, the interpretation of which is based on betwe en (F-st) and within-(F-is) population variability. Several computer progra ms are available and confidence intervals of each index are based on differ ent procedures. These programs (Genetix, Diploid, Genepop) were compared wi th a classical program (Biosys-1) using a large set of Haemonchus contortus isozyme data. The results were identical for all softwares for large diffe rences when natural populations were studied (F-st > 0.25 and F-is > 0.15 o r < -0.15). When small F-st were investigated in laboratory-reared populati ons, the significance of differences was often related to the software used . As a rule of thumb, it is suggested that at least two out of three softwa re packages (based on different calculation procedures) should give similar results before differences are validated.