The social modulation of behaviour, cognition and stress reactivity during pregnancy and lactation
Zusammenfassung der Projektergebnisse
The aim of this project was to investigate the adaptive significance of behavioural profiles, which were shaped by different social conditions during early phases of life. In the domestic guinea pig and their wild ancestor, the wild cavy, for example, sons, whose mothers had lived in an unstable social environment during pregnancy and lactation (UE-sons), showed a behavioural infantiliziation, and daughters (UE-daughters) a behavioural masculinization. Sons and daughters, however, whose mothers had lived during this period of life in a stable social environment (SE-sons/SE-daughters), were non-infantilized and non-masculinized, respectively. Thus, the different behavioural profiles are not a result of the artificial selection during domestication. Rather they represent maternal effects evolved through natural selection. To investigate the adaptiveness of the infantilized behavioural profiles of UE-sons we mimicked a high-density situation, which is characterized by a high degree of social instability representing a match for UE- and a mismatch for SE-sons. Each one UE- and SE-son was introduced to an established harem, i.e. an adult male was present. Under such conditions, an infantilized behavioural profile should represent an efficient adaptive mechanism: when populations expand and competition among species members increases, a male with an infantilized behavioural profile will be only rarely involved in interactions with adult males. This could be adaptive, because male wild cavies do not tolerate each other and severe injuries can occur during aggressive encounters. At low individual numbers, more-typical ‘male’ patterns would be of advantage. Highly interestingly, after an initial phase, in which both types of sons show a high degree of stress, UE-sons reached again basal values of cortisol concentrations, whereas SE-sons had high cortisol levels until the end of the experiment. Thus, UE-sons showed a more effective coping strategy in this matching social situation. However, in the corresponding second match-mismatch experiment (match for SE-, mismatch for UE-sons: low density, no adult males were present) no advantage in either the SE- or the UE-sons could be found. These results indicate that there might be social environments in which almost all behavioural profiles shaped in early life are doing well. In two further match-mismatch experiments we investigated the adaptiveness of the different behavioural profiles of the daughters: in high population density situations, important resources are scarce and a masculinized behavioural profile (characterized by strong competitive abilities) should be adaptive. In situations, however, in which all resources are sufficiently available, a non-masculinized behavioural profile should have advantages. Indeed, our results point to an adaptation of SE-daughters in a matched environment. The data of the other match-mismatch experiment are currently analysed. We compared furthermore emotional behaviour and stress reactivity between male wild cavy UE- and SE-offspring. Concerning mean values, no significant differences were found. However, on an individual level, emotional behaviour was highly repeatable in UE-, but not in SE-sons. SE-sons, in turn, had a stronger consistency in stress responsiveness than UE-sons. These results show that stress responsiveness and emotionality can be adjusted by the early social environment and may have different costs concerning their plasticity. Taken together, we could show clearly that the shaping of behavioural profiles by environmental stimuli during early phases of life represents an effective mechanism for rapid adaptation. Alarm im Hamsterrad / FAZ / 17.05.2015. Mensch, Kaninchen! / Süddeutsche Zeitung / 29.08.2014. Echte Persönlichkeiten / Wissen & Leben / Juli 2014. Vom Käfer bis zum Affen: Tiere haben Persönlichkeiten / Focus / 22.05.2014. Mamasöhnchen, Memmen und Mannweiber / Hamburger Abendblatt / 08.05.2014. Mamasöhnchen, Memmen und Mannweiber / Die Welt / 09.05.2014. Was ein Hausmeerschweinchen von einem wilden unterscheidet / der Standart / 12.04.2014. Was Haus- und Wildmeerschweinchen unterscheidet / bild der wissenschaft / 10.04.2014. Hausmeerschweinchen mögen es ruhig / Müsternsche Zeitung / 14.04.2014. Meerschweinchen – als Haustier gesellig / Westfälische Nachrichten / 10.04.2014.
Projektbezogene Publikationen (Auswahl)
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(2013): Behavioural profiles are shaped by social experience: When, how and why. Philos. Trans. R Soc. B 368 (1618)
Sachser, N., Kaiser, S. & Hennessy, M.
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(2013): Dimensions of Animal Personalities in Guinea Pigs. Ethology 119: 970-982
Zipser, B., Kaiser, S. & Sachser, N.
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(2013): Early social instability affects plasma testosterone during adolescence but does not alter reproductive capacity or measures of stress later in life. Physiol. Behav. 120: 143–149
Siegeler, K., Wistuba, J., Damm, O.S., von Engelhardt, N., Sachser, N. & Kaiser, S.
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(2014): Effects of domestication on biobehavioural profiles: a comparison of domestic guinea pigs and wild cavies from early to late adolescence. Front. Zool. 11: 30
Zipser, B., Schleking, A., Kaiser, S. & Sachser, N.
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(2015): Domestication affects the structure, development and stability of biobehavioural profiles. Front. Zool. 12(Suppl1): 19
Kaiser, S., Hennessy, M.B. & Sachser, N.
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(2015): Social instability during pregnancy and lactation alters female wild cavy offsprings’ endocrine status and behaviour later in life. Behaviour 152 (7-8): 837 – 859
Kaiser, S., Schwerdt, B., Siegeler, K. & Sachser, N.
