Lines connect allelic combinations present in the RFLP genotypes reported by Howe and Sibley (1995) to describe 106 T. gondii isolates. Bold lines indicate the hour glass shape expected when all four combinations of alleles that would be expected after a recombination (or reassortment) event are present in the isolates. Bi-allelic combinations that did not show evidence for recombination include: SAG1 vs SAG2, SAG1 vs ROP1, SAG2 vs 850, SAG2 vs ROP1, 850 vs ROP1, 850 vs L328, and ROP1 vs L328 (not shown).