48. THE GENETICS OF FISH* 



Through an intensive series of researches Gordon (1927-1948) has demonstrated that the 

 mechanism of inheritance is essentially Mendelian for fishes, as it has been proven to 

 be for all other groups studied. There are wild types (gray) of the Platy (Platypoecilus 

 maculatus) and domesticated albino and golden types which can be interbred readily. In 

 all, there are some 150 varieties of patterns in this one species, relatively few of which 

 have, as yet, been thoroughly analysed from a genetic point of view. Recently (1944- 

 1948) Dr. Gordon has concentrated on the inheritance of melanomas, which study is 

 closely akin to cancer studies on higher forms. 



The Platy is readily available at any Aquarium Supply House, and the three major vari- 

 eties (wild, albino, and golden) may be procured for simple genetic crosses. The golden 

 mutant arose from a wild stock in 1921 and the albino appeared first, also from a wild 

 stock, in 1934. When these mutants are interbred, the wild variety re-appears. 



Following are a series of genetic crosses that have been made by Dr. Gordon, indicating 

 clear-cut dominance and recessiveness of various pigment patterns. These are offered 

 here as suggestive of the type of study in the field of developmental heredity that is now 

 possible. (See pages 368-375 and also papers by Goodrich et al. ) 



ALBINO X ALBINO= ALBINO 



© 



GOLDEN X ALBINO = WILD 



BACK TO THEIR ANCESTRAL COLORS 



When the golden swordtails ore inbred, they produce nothing but golden; when the albino 

 swordtails are inbred, they produce nothing but albinos. When the golden swordtail is mated 

 with the albino, they produce young all of which have the coloring of the wild swordtail. 



* These figures are kindly loaned by Dr. Myron Gordon of the New York Zoological Society. See Gordon's "The Physiology of 

 Fishes", Academic Press 1957. 



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