PhD defense 3 Mai 2011 _ Social networks and complex behaviours in sharks

I just defended my PhD on behavioural ecology of sharks in French Polynesia. Here is the abstract:


Social networks and complex behaviours in sharks



Social behaviour is widespread in the animal kingdom. Despite evidence of shark aggregations, little is known about their organisation and behaviour. In this thesis, the patterns and mechanisms underlying the social organisation of free-ranging sharks were investigated using the blacktip reef shark (Carcharhinus melanopterus) as a model species. Social organisation is often influenced by the spatial distribution of individuals. Strong site attachment displayed by blacktip reef sharks suggests possible repeated interactions between individuals as a prerequisite for sociality. Spatio-temporal associations between individuals allowed building a social network that describes non-random social preferences between 133 individual sharks. As the social organisation is also characterised by different strategies, molecular analyses revealed that females return to the same nursery to give birth and that many offspring show a high degree of inbreeding. At the end, the influence of genetic similarity on the social behaviour of sharks was investigated, revealing that sharks were more related within than among social groups. This thesis reveals for the first time evidence of a complex social organisation in adult sharks, indicating that group formation is an important behavioural strategy for sharks that likely improves survival and fitness. Often considerate as primitive and solitary animals, sharks appear to be able of complex social behaviour and underlying strategies. These results emphasise the need to include these novel insights into conservation plans.


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