Subject females were allowed to interact with both stimulus females consecutively over two days. The order with which subject females encountered the related and unrelated stimulus females was randomised. Stimulus order was included in the model initially and then removed if not significant. The amount of investigatory, associative and competitive behaviour performed by subject females was compared when the subject females interacted with a related female and an unrelated female. The related stimulus female was either a maternal half-sister or a paternal half-sister. Subject females had encountered the urine of both stimulus females in the scent discrimination and attraction assay, and had limited interaction with both stimulus females in the nest partner choice assay.
3.4.3.1 Investigatory Behaviour
The amount of time subject females spent performing investigatory behaviours towards related and unrelated stimulus females was compared. Stimulus order was not significant (F(1,33) = 0.98, p = 0.33) and so was removed from the model. There was a significant interaction between the level of investigatory behaviour and the lineage group (F(1,35) = 7.77, p = 0.01; Figure 3.6). Investigation of the data revealed that this was due to females in the maternal half-sister group displaying more investigatory behaviour towards the unrelated stimulus female than towards the related stimulus female, whereas in the paternal half-sister group subject females investigated related stimulus females more than unrelated stimulus females. There was no difference in the amount of time subject females investigated either the related or unrelated females (F(1,35) = 1.25, p = 0.27; Figure 3.6) and no difference between the lineage groups (F(1,35) = 0.06, p = 0.81; Figure 3.6).
3.4.3.2 Associative Behaviour
The amount of time subject females spent performing associative behaviours towards related and unrelated stimulus females was compared when related females were either maternal or paternal half-sisters. The ratio of time subject females spent performing associative behaviours towards the related stimulus female did not differ with stimulus order (z = -0.66, p = 0.52, two-tailed). There was no difference in the ratio of time spent performing associative behaviours by subject females towards the related stimulus females between the lineage groups (z = -1.36, p = 0.18, two-tailed; Figure 3.7). The data from the two lineage groups were therefore combined and the amount of time spent by subject females performing associative behaviours was compared. Subject females did not differ in the amount of time
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they spent performing associative behaviours towards either related or unrelated stimulus females (z = -1.15, p = 0.26, two-tailed; Figure 3.7).
3.4.3.3 Competitive Behaviour
The amount of time subject females spent performing competitive behaviours in response to related and unrelated stimulus females was compared when related females were either maternal or paternal half-sisters. There was no difference in the ratio of time females spent performing competitive behaviours towards related females when females were tested with a related or an unrelated stimulus female first (z = - 0.47, p = 0.66, two-tailed; Figure 3.8). Females in the maternal and paternal lineage groups did not differ in the ratio of time spent performing competitive behaviours towards related stimulus females (z = -0.86, p = 0.40, two-tailed; Figure 3.8), and therefore the two lineage groups were combined. Subject females spent longer performing competitive behaviours towards unrelated stimulus females than towards related stimulus females (on average subject females performed 11.57 s competitive behaviour towards related stimulus females and 23.83 s competitive behaviour towards unrelated stimulus females; z = -2.10, p = 0.04, two-tailed; Figure 3.8).
3.4.3.4 Full Sister Interactions
The interaction assay had not previously assessed differences in behavioural response between full sisters and unrelated females. To investigate whether full sisters might show a stronger response than half-sisters interaction trials were run using 14 female triads where related females were unfamiliar full sisters. All methods were as described in Section 3.3.7. Females had been bred during the breeding programme documented in Section 3.3.2. not previously been used in any behavioural assays and were unfamiliar with both stimulus females. Subject females and stimulus females were 8 and 10 months old respectively. The triads of subject and stimulus females were assigned based on the methods described in Section 3.3.4. Two 15 minute trials were run over two days and stimulus female order was randomised. All stimulus females were fur bleached for identification. Assays were recorded to DVD and watched back blind to the identity of the stimulus female. Behaviours recorded are described in Table 3.3.
Investigatory behaviour was square root transformed to meet parametric assumptions. The amount of time subject females spent performing investigatory behaviours towards related and unrelated stimulus females was compared using a repeated measures GLM. There was no difference in the amount of time subject females spent performing investigatory behaviour
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towards the related or unrelated stimulus females (F(1,12) = 2.68, p = 0.13; Figure 3.6) and no effect of stimulus order (F(1,12) = 0.29, p = 0.60). The ratio of time subject females spent performing associative behaviours towards related stimulus females did not differ with stimulus order (z = -0.39, p = 0.72, two-tailed, Mann-Whitney test). Subject females did not differ in the amount of time spent performing associative behaviours towards related or unrelated stimulus females (z = -0.66, p = 0.54, two-tailed, Wilcoxon Signed Ranks test; Figure 3.7). The ratio of time subject females spent performing competitive behaviours towards related stimulus females did not differ with stimulus order (z < 0.001, p = 1.00, two- tailed, Mann-Whitney test). There was no difference in the amount of competitive behaviour subject females performed towards related or unrelated stimulus females (z = -0.87, p = 0.41, two-tailed, Wilcoxon Signed Ranks test; Figure 3.8).
Figure 3.6: Investigatory behaviour in the maternal and paternal half-sister groups, and the full sister group.
Investigation (s, mean + standard error) of related (grey bars) and unrelated (open bars) stimulus females in the full sister (n = 14), maternal half-sister (n = 20) and paternal half-sister (n = 17) groups.
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Figure 3.7: Associative behaviour in the maternal and paternal half-sister groups, and the full sister group.
Associative behaviour (s) towards related (grey bars) and unrelated (open bars) stimulus females in the full sister (n = 14), maternal half-sister (n = 20) and paternal half-sister (n = 17) groups.
Figure 3.8: Competitive behaviour in the maternal and paternal half-sister groups, and the full sister group.
Competitive behaviour (s) towards related (grey bars) and unrelated (open bars) stimulus females in the full sister (n = 14), maternal half-sister (n = 20) and paternal half-sister (n = 17) groups.
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