BULLETIN No. 218. 



TABLES FOR CALCULATING COEFFICIENTS OF 



INBREEDING.* 



Raymond Pearl and John Rice; A'Tiner. 



In two recent papers from this laboratory** a method of 

 measuring the degree of inbreeding exhibited in a particular 

 pedigree has been described. This method consists in the deter- 

 mination of coefficients of inbreeding, which are quantities 

 defined by the equation 



„ ioo(/^n+i— ?n+l) 



^n= 7 , (1) 



Yn+X 



where Zn denotes the coefficient of inbreeding for any particu- 

 lar ancestral generation n; p^,^ the maximum possible number 

 of different ancestors in the preceding generation; and q ^,-, 

 the actually realized number of different ancestors in that gen- 

 eration. 



It is believed that this method of measuring inbreeding may 

 be of a great deal of practical value to the stock breeder in 

 his study of pedigrees. If this is to be the case, however, it is 

 esisential that the computation incident to the application of the 

 method be reduced to the smallest possible amount and the sim- 

 plest terms. In order to attain this end the accompanying ta- 

 bles have been prepared. 



In the paper referred to above a very simple method was 

 described for finding the values of the successive (p — a \ 



. . . ° ' n + l J- n+1 ) 



quantities. This consisted in the formation for each pedigree 

 studied of a table in which each primary reappearance of an 

 animal was listed for the generation in which it reappeared, to- 



*Papers from the Biological Laboratory of the Maine Agricultural 

 Experiment Station. No. 51. 



**Pearl, R. A Contribution Towards an Analysis of the Problem of 

 Inbreedmg. American Naturalist, Vol. XLVII, pp. 577-614, 1913. 



c- ~T.^"'^„ ^leasurement of the Irtensity of Inbreeding. Me. Agr Expt. 

 Sta. Bulletm 215, pp. 123-138, 1913. 



