Figure 5

A two mating type (MT) system does not fit the data. In the diagram, parental trypanosomes J10 and 1738 are arbitrarily designated MT A or B. The four F1 progeny clones successfully produced hybrids when crossed in all pairwise red/green combinations and therefore, in a two MT system, the green and red F1 clones should be of different MT as shown. The model predicts that half the back crosses should fail, because only clones of different MT are compatible; however, seven of the eight back crosses successfully produced hybrids (Table 1). Therefore a two MT system does not fit the data. Solid and broken lines indicate back crosses that produced or did not produce hybrid progeny respectively.