212 Miscellaneous Linkage Topics 



Diplotene Configuration Chromatids 



1 ) Reciprocal 

 L 



P 



P 



> 4 noncrossovers 



^2) Complementary 



► 4 crossovers 



3) Diagonal -1 



3\ 



P 

 P 



2 crossovers 

 2 noncrossovers 



(4) DiagonaI-2 

 L 



2 crossovers 

 2 noncrossovers 



Total: 8 crossovers 



8 noncrossovers 



Fig. 67. Compound crossing over. The four possibilities of chiasma 

 formation when two chiasmata are formed in one bivalent, and the chroma- 

 tids produced from each type. For explanation, see text. (Based on 

 Mather in the Biological Reviews.) 



