hl2 



EXPERIMENTAL FISH EMBRYOLOGY 



GOLDEN X ALBINO = WILD 



When 

 blno sword 

 is mated w 

 swordtail . 



BACK TO THEIR ANCESTRAL COLORS 



tlie fi,olden swordtails are liibred, tliey produce notliing but golden; when the al- 

 tails are inbred, they produce nothing but albinos. When the golden swordtail 

 itli the albino, tliey produce young all ol' whicli have the coloring of the wild 



U 



About 1921 

 WILD X WILD 



WILD 

 WILD 



WILD 

 golden 



WILD 

 golden 



WILD 

 WILD 



About 1954 



WILD X WILD 



\ 



WILD 

 WILD 



WILD 

 albino 



WILD 



albino 



WILD 

 WILD 



WILD 



WILD WILD 



WILD X golden 



406 

 WILD WILD 



4b 



WILD X WILD 



WILD WILD WILD 



albino X WILD 



HISTORY OF SEPARATION AND REUNION OF COLOR GENES IN THE SWORDTAIL 



This chart shows tlie independent origin ol' Llie golden and the albrno, and the results 

 obtained when these mutations were crossed. The backcrosses ol" the "synthetic" wilds to 

 golden and albinos show tlie genetic structure of these differences. Some of the dis- 

 crepancies in the ratios in tlie oackcross and K., results may be accounted for by the dif- 

 ferential viability of the three types of swordtails. The albino is the weakest, and the 

 golden is definitely weaker than the wild tj-pe. The total of 334 Fo offspring is made up 

 of the progeny of several females. Some Kj matlngs produced Fo youn^; In the ratio of 

 9:3:1 so closely as to be remarkable. 



