The guppy Poecilia reticulata has proven a model species for behavioural ecology; in this thesis, its patterns of group-living were examined in a variety of contexts. These fish engage in inspection, the risky approaching of a predator to gain information on the threat posed. To lessen this risk, guppies may cooperate by approaching together, taking it in turns to advance. The temptation is for fish to defect by holding back and observing the inspection of others, gaining information at their partner's expense. Theory predicts that individuals should associate with those that have been previously cooperative in order to avoid being defected against. To test this, I quantified the social networks of wild-caught female shoals of guppies and then exposed them to a pike cichlid predator Crenicichla frenata. Guppies that inspected together frequently were both more cooperative and more associated in the network than infrequently inspecting partners. Simulating defection by preventing some fish inspecting. in similar female shoals, I found, contrary to predictions, that there was no change in the preference of others. to partner with them afterwards. Guppies appear to assort with respect to cooperation but not reassort in response to defection. Additional experiments found that the number of fish, and thus the number of partners to choose from, did not change how cooperative fish were during inspection, perhaps because of consistent partner choice. I then examined if these stable partnerships observed in the laboratory occurred in the much larger social networks seen in the wild. I found that female guppies of similar inspection tendencies interacted more often than predicted by random models. If guppies prefer shoaling with particular individuals over others, they may learn preferentially from others also. Testing shoals of domestic female guppies in a novel foraging task, naIve guppies performed the task fas~er when a trained fish was highly connected to them in their social network. However, if there were two trained fish with conflicting tasks, then they performed the task of the less connected fish faster. The network position of trained fish appears to impact upon the potential for social learning of naIve fish but other factors, e.g. the competitive ability of the trained fish, may influence how naIve fish act on that information. Thus we see that the benefits to a fish of shoaling with others depend upon the shoaling partners chosen and that guppies exercise this choice with care in a number of contexts.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:485597 |
| Date | January 2007 |
| Creators | Thomas, Philip Richard |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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