Spearman rank correlation tests were used to estimate effects of isolation age on the age of development of stereotypies and polydipsia. Intersex differences in stereotypy fre-
quencies and water consumption were tested with chi-square tests using Yates continuity correction factor. The same test was used on data from polydipsic and non-polydipsic
voles with respect to glucosuria. The chosen significance level was 0.05 and the tests were two-tailed. Corrections for ties were performed if necessary.
3. Results
3.1. Stereotypies Ž .
Ž Table 1 illustrates the proportion of animals in the four classifications W, S, PD
. and PDS in each of the two generations.
No individuals in the P generation developed stereotypies, whereas stereotypic Ž
. behaviour was observed in 37 F1 individuals S q PDS . There were no sex differ-
ences in the number of S q PDS animals, but significantly fewer males than females Ž . Ž
. developed stereotypies alone S
P - 0.05 . Approximately 10 of the F1 animals developed two or more different types of stereotypies. The distribution of different types
Ž .
of stereotypies in F1 is depicted in Fig. 1. The preferred stereotypy was BS P - 0.0001 . Ž
. Ž
. JUMP was preferred over PF P - 0.01 and WIN P - 0.0001 , and no sex differences
were shown in stereotypy distribution. Table 2 shows the age at which the F1 voles were classified as S, PD and PDS.
Stereotypies were developed at the age of 96 days for both sexes. Comparisons of the Ž
. two most common types of stereotypies showed that JUMP appeared earlier 60 days
Ž . Ž
. than BS 105 days
P - 0.0001 . There were no relationships between the age at isolation and age at which stereotyp-
ies were observed, and there were no effects of isolation age on the number of stereotyping voles.
Table 1 Ž .
Ž . Ž
. Proportion
of male and female voles classified as stereotypers S , polydipsic
PD and as both
Ž .
stereotypers and polydipsic PDS in P and F1 ClassificationrGeneration
W S
PD PDS
PDqPDS SqPDS
P Ž
. Males ns 38
66 34
34 Ž
. Females ns 54
87 13
13 Malesqfemales
78 22
22 F1
Ž .
Males ns138 38
23 30
9 38
32 Ž
. Females ns110
46 38
11 6
16 44
Malesqfemales 42
30 21
7 29
37 P -0.05.
P -0.001.
Ž . Fig. 1. Proportions of male and female voles showing different types of stereotypies. The total exceeds
100 because some voles showed two or more stereotypies. Abbreviations as in text.
3.2. Polydipsia Ž
There were no significant differences between the occurrence of polydipsia PD q .
Ž .
Ž .
PDS in P 22 and F1 29 , but the proportion of polydipsic males was more than Ž
twice the proportion of polydipsic females in both generations P: P - 0.05; F1:
. Ž .
P - 0.001 Table 1 . Daily water consumption in male and female W voles was 9.8 and 9.0 mlrday, respectively. S males drank 9.2 mlrday and S females reached 10.3
Ž .
mlrday P - 0.05 compared with W females . PD males drank 67.0 mlrday and PD females reached 60.8 mlrday, while PDS males and females drank 65.6 mlrday and
50.7 mlrday, respectively. There was no sex effect on water consumption. There was no sex difference in age for showing polydipsia, but polydipsia was
Ž . Ž
. developed later than stereotypies in males 60 vs. 99 days, P - 0.001 Table 2 . There
Table 2 Ž .
Ž .
Average age in days for the occurrence of stereotypies S and polydipsia PD PDS-S and PDS-PD indicate age for classification as S and PD in voles showing both stereotypies and
polydipsia. Differences between different classifications are shown below. Day of observation
S PD
PDS-S PDS-PD
F1 Ž
. Males ns85
99 60
86 62
Ž .
Females ns60 94
74 90
114 Malesqfemales
96 63
87 79
Day of observation Males
Females Malesqfemales
S vs. PD NS
S vs PDS-S NS
NS NS
S vs. PDS-PD NS
PD vs. PDS-S NS
PD vs. PDS-PD NS
NS PDS-S vs. PDS-PD
NS NS
P -0.05. P -0.01.
P -0.001.
Table 3 Proportion of polydipsic and non-polydipsic voles tested positive and negative for glucosuria
Glucosuria Positive
Negative Ž
. Polydipsic ns 20
65 35
Ž .
Non-polydipsic ns 20 100
P -0.001.
were no effects of isolation age on the number of voles developing polydipsia, the time for polydipsia to occur or the amount of water consumed.
3.3. Stereotypies and polydipsia Ž
. Approximately 7 F1 voles were classified as PDS Table 1 with no significant
difference related to sex. Ž
. Ž
. PDS animals developed polydipsia later 79 days than PD animals 63 days , and
Ž . Ž
. this was especially pronounced in females 114 vs. 74 days, P - 0.05 Table 2 .
Ž .
Comparisons between all non-stereotyping voles W q PD, n s 156 and all stereo- Ž
. typing voles S q PDS, n s 92 showed that polydipsia occurred most frequently in
Ž .
non-stereotypers W q PD: 34; S q PDS: 20, P - 0.05 . 3.4. Polydipsia and glucosuria
Ž . Table 3 shows the proportion of voles tested positive for glucosuria. None of the
non-polydipsic voles were tested positive, whereas 65 polydipsic voles showed clear Ž
. signs of glucosuria P - 0.001 .
4. Discussion
