These comparisons indicate t±at the 

 Yellowstone cutthroat trout is a very plastic 

 subspecies so far as spotting, hyoid teeth, and 

 body coloration are concerned and that wide 

 natural variations in these characters can be 

 expected. Data are insufficient to determine 

 how much of the differences reported in this 

 study are of actual genetic origin as environ- 

 mental conditions were not constant among the 

 four populations sampled. Some genetic change 

 in spotting and hyoid teeth abundance is suggest- 

 ed as levels of difference varied directly with 

 length of isolation in most comparisons. Con- 

 trolled laboratory studies will be necessary to 

 determine the cause of these differences, but 

 their magnitude clearly indicates that the usual- 

 ly accepted levels for separating species and 

 subspecies are not applicable to field collections 

 of Salmo c. lewisi. The value of coloration, 

 spotting, and hyoid teeth in classifying cutthroat 

 subspecies obviously needs to be reassessed. 



Literature cited 



Benson, Norman G. , and Ross V. Bulkley. 



1963 . Equilibrium yield and management of 

 cutthroat trout in Yellowstone Lake. 

 U. S. Fish and Wildlife Service, 

 Research Report 62 . In press. 



Cope, Oliver B. 



1957. Races of cutthroat trout in Yellow- 

 stone Lake . In Contributions to the 

 study of subpopulations of fishes. 

 U.S. Fish and Wildlife Service, 

 Special Scientific Report--Fisheries 

 No. 208, pp. 74-84 



DeWitt, John W. , Jr. 



1954. A survey of the coast cutthroat trout, 

 Salmo clarki clarki Richardson , in 

 California. California Fish and Game, 

 vol. 40, No. 3, pp. 329-335. 



Dymond, J. R. 



1928 . The trout of British Columbia . 

 Transactions American Fisheries 

 Society, vol. 58, pp. 71-77. 



Hubbs, Carl L. , and Clark Hubbs. 



1953 . An improved graphical analysis and 

 comparison of series of samples. 

 Systematic Zoology, vol.2, No. 2, pp. 49 -57. 



Kendall, W. C. 



1915. The fishes of Yellowstone National 

 Park. Report U. S. Commissioner of 

 Fisheries for 1914, Appendix VUI, 

 pp. 1-28. 



Mayr, E., E. G. Linsley, andR.L. Usinger. 

 1953. Methods and principles of systematic 

 zoology. McGraw-Hill, New York. 

 328 p. 



Miller, Robert Rush. 



1950. Notes on the cutthroat and rainbow 

 trouts with the description of a new 

 species from the Gila River, New Mex- 

 ico. University of Michigan Museum of 

 Zoology, Occasional Papers, No. 529, 

 pp. 42. 



Needham, Paul R. , and Richard Card. 



1959. Rainbow trout in Mexico and California, 

 with notes on the cutthroat series. 

 University of California Publications in 

 Zoology, vol. 67, No. 1, pp. 1-124. 



Quadri, S. U. 



1959. Some morphological differences be- 

 tween the subspecies of cutthroat trout, 

 Salmo clarkii clarkii , and Salmo clarkii 

 lewisi, in British Columbia. Journal, 

 Fishery Research Board of Canada, 

 vol. 16, No. 6, pp. 903-922. 



Royce, William F. 



1957. Statistical comparison of morphologic- 

 al data, jn Contributions to the study of 

 subpopulations of fishes . U. S. Fish 

 and Wildlife Service, Special Scientific 

 Report--Fisheries, No. 208, pp. 7-28. 



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