1 research outputs found
The decision to approach or avoid: Influence of social experiences during development on the establishment of consistent inter-individual differences and the role of neuromodulators in Gryllus bimaculatus
Intraspecific aggression is a widely distributed, highly plastic behaviour throughout the animal kingdom and serves to secure resources, as members of the same species compete for identical ecological niches. But the costs can rapidly exceed the advantages. Over the past years, the two-spotted Mediterranean field cricket, Gryllus bimaculatus, has emerged to a model organism for studying the mechanisms underlying aggressive behaviour. Crickets implement seemingly complex decisions via the action of well-known neuromodulators with analogues in vertebrates including humans. This study shows that an individual´s decision to approach or avoid an agonistic stimulus is mainly shaped by social experiences gathered during nymphal development and early adult life. In particular, the chronic subjugation of nymphs by adult males in the breeding colony and the absence thereof lead to the establishment of distinct behavioural ethotypes shifting the answer to the question of whether inter-individual differences are nature or nurture in favour of nurture. Individuality in adult behaviour can thus result from social experiences during development alone. Moreover, the decision to approach or avoid a potentially agonistic stimulus is differentially modulated by the actions of the neuromodulators octopamine, serotonin and nitric oxide, which are released in response to social interactions. Interestingly, the social status dependent predisposed response to an antennal stimulus can be altered by octopamine alone. Furthermore, the present study reveals that the nitridergic and serotonergic system play a major role in the assessment of agonistic signals.:1 Introduction ...................................................................................................... 1
2 Methods ............................................................................................................ 6
2.1 Experimental animals .................................................................................... 6
2.2 Experimental groups based on social experiences
and isolation time .................................................................................. 8
2.3 Evaluation of dominance and subordination ......................................... 10
2.4 Multiple wins and defeats ...................................................................... 12
2.5 Contests against a hyper-aggressive opponent .................................... 13
2.6 The mandible threat display in response to antennal stimulation and feeding ............................................................................. 13
2.7 The priming effect .................................................................................... 14
2.8 Influence of food as a resource ............................................................... 14
2.9 Set up and video tracking ....................................................................... 15
2.10 Evaluation of exploratory behaviour ..................................................... 16
2.11 Response to a single antennal touch with an adult male´s
antenna ..................................................................................................... 17
2.12 Pharmacological treatment ...................................................................... 18
2.13 Data analysis ............................................................................................. 20
3 Results ............................................................................................................ 22
3.1 Responses of nymphs and adults towards conspecifics ........................... 22
3.2 Mandible threat display and the mandible spread angle .......................... 24
3.3 Influence of dominance and subordination ................................................. 26
3.4 Influence of prior antennal stimulation (priming) .......................................... 28
3.5 Influence of priming coupled with CDM ...................................................... 30
3.6 Influence of food as a resource .................................................................... 30
3.7 Effects of different social experiences during nymphal
development on adult behaviour ................................................................. 31
3.8 Turning responses as a reaction to a single antennal touch
with an adult male´s antenna ....................................................................... 34
3.8.1 Short term isolates ............................................................................... 34
3.8.2 Long term isolates ............................................................................... 38
3.9 Effects of neuromodulatory drugs on behavioural
elements in STI and LTI crickets ............................................................... 43
3.9.1 Aggression ............................................................................................ 43
3.9.2 General motility .................................................................................... 46
3.9.3 Turning responses ................................................................................. 50
3.9.3.1 Influence of octopaminergic drugs .................................... 50
3.9.3.2 Influence of nitridergic drugs ............................................... 53
3.9.3.3 Influence of serotonergic drugs .......................................... 58
4 Discussion .................................................................................................... 68
4.1 Nymphal interactions and their consequences for adult behaviour .......... 68
4.2 The decision to approach or avoid an agonistic stimulus ........................... 72
4.3 The role of neuromodulators released in response to social experience .... 77
4.4 Overall conclusion and outlook .................................................................... 84
5 Summary .......................................................................................................... 86
6 Zusammenfassung ........................................................................................... 91
7 References ........................................................................................................ 98
8 Appendix .......................................................................................................... 109
8.1 Figures and Tables .......................................................................................... 109
8.2 Publications and published abstracts ............................................................ 111
8.3 Curriculum vitae ............................................................................................ 113
8.4 Acknowledgments ......................................................................................... 11