The effects of familiarity on the social interactions of juvenile lemon sharks, Negaprion brevirostris

Investigating individual preferences using Social Network Analysis (SNA) has contributed to understanding group formations, which hold significant evolutionary value, and the dynamics occurring within them across the animal kingdom. Groups of sharks have been observed for centuries, and understanding the mechanisms that facilitate their formation furthers our comprehension of the adaptive value of sociality. However, there is a dearth of quantitative analyses on these mechanisms. The preference for familiars can influence group formation and facilitate an increased level of fitness. This preference has been documented across many vertebrate classes, but has not been shown to have an overall effect on partner preference in chondrichthyan fishes. This deficiency is significant due to the taxa's ecological diversification and importance. In this study, we used behavioral experiments to assess the potential role of familiarity in group formation and on social behavior in a large marine vertebrate. Juvenile lemon sharks, Negaprion brevirostris, (N = 23) in Bimini, Bahamas, were separated into holding pens according to their size and given 14 days to familiarize with their cohort. Two pairs of sharks were selected from separate holding pens and introduced in a social network pen for a behavioral trial. SNA indicated that N. brevirostris showed a significant preference for familiar individuals, performing more social interactions, such as closely following, with individuals from their holding pen. We suggest that this preference for familiars is developed through repeated interactions and facilitates the advantages of maintaining stable behavioral interactions, which results in spatial isolation from unfamiliars. These findings advance our understanding of the mechanisms driving social structure in N. brevirostris and other large marine predators, which contribute to an animal's overall fitness and evolutionary adaptability. (C) 2017 Elsevier B.V. All rights reserved.