Animal Social Network

My research is trying to understand what drives sociality in the marine environment with a special focus on elasmobranchs.

While sociality has been extensively studied in terrestrial animals, less is known about the causes, forms and consequences of sociality in the marine environment [except for marine mammals]. My research attempts in better understanding the emergence of social behaviour and social structure in marine animals. In particular, I try to understand how behaviour shapes social networks and govern social processes, and how it influences the structure and processes at the population level.

My main models have been sharks & rays so far.

Anecdote:

During my PhD, when conducting underwear visual surveys, I noticed that I could identify each individual based on specific coloration patterns on their fins (see Photo-ID section in Methods) and I had that feeling that some individuals were at the site always together. In turn I decided to test the hypothesis of preferred associations (like the presence of friendship). Searching the bibliography, I decided to use social network analyses such it was done on dolphins to investigate this question. By monitoring a 10km reef section of the island of Moorea (French Polynesia) for two years (>200 dives), I recorded every individual I encountered and social network analyses revealed that sharks were developing non-random associations but also structured their population into social community based on social preferences and sharing space (Mourier et al. 2012; Mourier et al. 2017). Further investigations revealed that such associations were not based on family relationships but rather on other processes such as familiarity (Mourier & Planes 2021).

Comparison of association, affiliation and genetic relatedness networks in a population of blacktip reef sharks (Carcharhinus melanopterus) in French Polynesia (Mourier & Planes 2021)

I expended my work on marine sociality to other contexts and species in building collaborations with other scientists interested in the same research topic, including David Jacoby, Culum Brown, Yannis Papastamatiou, Tristan Guttridge, David Villegas-Rios and others. Here is a link to our recent Research Topic in Frontiers in Marine Science that will explore Sociality in Marine Environment more broadly.

Here is a list of projects on animal social networks I have led or being involved:

- The emergence of social networks in blacktip reef sharks – led by Johann Mourier & Serge Planes

- Emergence of collective and social behaviour of hunting grey reef sharks – led by Johann Mourier, Laurent Ballesta, Yannis Papastamatiou & Charlie Huveneers

- Social interactions in Port-Jackson sharks’ mating ground – led by Culum Brown, Tristan Guttridge and Johann Mourier

- Social interactions in the great white sharks – led by Yannis Papastamatiou

- Intra- and interspecific interactions in Carcharhinid sharks in the Mediterranean Sea – led by Ziv Zemah-Shamir

- Manta ray social and movement networks – led by Rob Perryman

- Sociality in developing in a family-living lizard – led by Julia Riley

Social network of temporal overlap of dusky sharks (C. obscurus) and sandbar sharks (C. plumbeus) based on their hourly co-occurrence (A) and based on the overlap in temporal windows (B). Nodes represent individual sharks with shape representing the species (square = sandbar shark, circle = dusky shark) and color representing sex (blue = male, red = female). Edge width is proportional to the simple ratio index (SRI) and its color represents a species-specific interaction (red = between sandbar sharks, blue = between dusky sharks, and grey = between sandbar and dusky sharks) (Zemah-Shamir et al. 2022)

I have also investigated what we call “heterarchy”, which is the link between social network and dominance hierarchy. With PhD candidate Pierpaolo Brena we used an innovative video recording setting that allowed us to remotely film sharks from above and sideways and to record interactions around a bait. This study allowed us to describe the tolerance network as well as reveal that the hierarchy was relatively steep and was not related to body size. In addition it revealed that sharks were able to observe and interpret the behaviour of their neighbours to behave based on this information.

Investigation of the link between tolerance and dominance hierarchy in sicklefin lemon sharks in the context of food competition. Adapted from Brena et al. (2018).

Future work will need to be conducted in the wild to better investigate the importance of social network for marine organisms. This will be possible by the continuous advancement in new technologies allowing to track individuals and their interactions at finer spatial and temporal scales.

Advancements in technologies will help improving our understanding of the importance of social networks in marine organisms (Villegas-Ríos et al. 2022).