Fig. 1.

Principal Co-ordinate Analysis plots. The plots show individual Haemonchus contortus L1s from field populations without a history of macrocyclic lactone use (F102− and F86−) and field populations with a history of frequent macrocyclic lactone use (F101+ and F5+). The plots show little differentiation between individuals from different farm populations, other than some clustering of individuals from F102−, which is consistent with the Analysis of Molecular Variance partitioning of genetic variation and the population fixation index values.