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100
80
60
40
20
0
Generation
FIGURE 8.4
Time far in the treadmill lines of Japanese quail selected for high or low level of
social reinstatement behavior over 20 generations. (
&
) HSR, (
e
) CSR, (
x
) LSR.
300
200
100
0
Generation
FIGURE 8.5
Duration of tonic immobility in lines of Japanese quail selected for high or low
level of social reinstatement behavior over 20 generations. (
&
) HSR, (
e
) CSR, (
x
) LSR.
Control SR birds had intermediate times (
Figure 8.4
). Over 20 generations
of selection, the duration of the tonic immobility response was remarkably
constant and similar in all three of the lines selected for social reinstatement
lines (
Figure 8.5
). This shows that tonic immobility and social reinstatement are
separate traits that are genetically independent of each other.
In the first generation (F0) of the lines to be selected for differing duration
of TI responses, the mean (
52.9)
seconds. After 20 generations of divergent selection, TI scores were 215.6
(
SD) value for the duration of TI was 50.5 (
6
6
6
91.9) seconds in the long TI line, 50.8 (
6
38.4) seconds in the control TI
line, and 9.3 (
11.6) seconds in the short TI line (
Fig. 8.6
).
The tonic immobility response in the long TI (high fear) line was approx-
imately 3.5 minutes compared to only 9 seconds in the short TI (low fear)
6
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