164 



CHAPTER 20 



In other words, Lamarckiana behaves as 

 though it contains two complexes of linked 

 genes. Within a strain these genes are com- 

 pletely linked by some mechanism that pre- 

 vents recombination, so that only two kinds 

 of genotypes are found in the gametes. The 

 two gene complexes are so constant in natural 



populations of a strain that they are given, 

 in the case of Lamarckiana, the names gaudens 

 and velans, so that this strain can be identified 

 as gaudens. velans, whereas biennis can be 

 described by its gene complexes as albi- 

 cans.rubens. Figure 20-4 shows how these bal- 

 anced lethal gene complexes are distributed 



FIGURE 20-4. Balanced lethal gene complexes in O. biennis and O. Lamarckiana. 

 BIENNIS = LAMARCKIANA = 



Albicans (A) Gaudens (G) 



GAMETES 



PLANT 



GAMETES ((O)) G 



^ PLANT 



O) A R (•) GAMETES (O) G 



PLANT 



/ \ 



/ \ 



