Íslenskar landbúnaðarrannsóknir - 01.03.1970, Síða 81

COLOUR INHERITANCE IN ICELANDIC SHEEP 79
TABLE 39. Continued
B. Matings involving only genotype A\A\, A\A$ and dgdg
Type of birth Lamb group
Mating wm nm wf nf Total DF X2
AiAi x AiA5 S 76 75 151 1 0.007
T 125 137 262 1 0.550
S + T 201 212 413 1 0.293
AiAi X A5A5 S 42 32 74 1 1.351
T 80 60 140 1 2.857
S + T 122 92 214 1 4.206*
AiAg x A1A5 S 55 17 40 22 134 3 4.245
T 95 18 96 37 246 3 6.791
S + T 150 35 136 59 380 3 6.765
A1A5 X AgAg S 9 9 17 22 57 3 8.614*
T 32 22 38 22 114 3 6.561
S + T 41 31 55 44 171 3 6.848
AgAg X AiAg S 7 9 7 11 34 3 1.294
T 10 18 18 24 70 3 5.657
S + T 17 27 25 35 104 3 6.308
AgAg X A5A5 S 43 44 87 1 0.012
T 65 57 122 1 0.525
S + T 108 101 209 1 0.234
Total number of progeny 1491
then only be found among white ewes.
Table 41 sliows the x2’s from table 39 B
classified according to white and nonwhite
ewes for singles and twins separately ancl
for singles and twins combined.
Table 41 shows that relatively more of
the variation can be attributed to non-
wliite ewes. The sum for singles and twins
among white ewes gives x2i4 = ^8.544
(0.20 > P > 0.10) while for nonwliite ewes
one obtains x2io = 19-920 (P < 0.05). This
excludes embryonic mortality among white
ewes as the only underlying source of varia-
tion in table 39 B, and one is inclined to
believe that selective fertilization might
play a part in the process.
G. SELECTIVE FERTILIZATION AND
EMBRYONIC MORTALITY
Several attempts have been made to de-
velop a model which would explain the
variation in segregation ratios in table 39 B
in terms of selective fertilization and em-
bryonic mortality.
The model that gave the best fit to the