BRIEF RESEARCH REPORT published: 21 November 2019 doi: 10.3389/fmars.2019.00718 Edited by: Jeffrey C. Mangel, Pro Delphinus, Peru Reviewed by: Gail Schofield, Queen Mary University of London, United Kingdom Francisco Concha, University of Valparaíso, Chile Sebastian Alberto Klarian, Andres Bello University, Chile *Correspondence: Amandine D. Marie amandine.marie@inra.fr Ciro Rico ciro.rico@usp.ac.fj † These authors have contributed equally to this work Specialty section: This article was submitted to Marine Megafauna, a section of the journal Frontiers in Marine Science Received: 25 July 2019 Accepted: 06 November 2019 Published: 21 November 2019 Citation: Marie AD, Stockwell BL and Rico C (2019) DNA Analysis of Juvenile Scalloped Hammerhead Sharks Sphyrna lewini (Griffith, 1834) Reveals Multiple Breeding Populations and Signs of Adaptive Divergence in the South Pacific. Front. Mar. Sci. 6:718. doi: 10.3389/fmars.2019.00718 DNA Analysis of Juvenile Scalloped Hammerhead Sharks Sphyrna lewini (Griffith, 1834) Reveals Multiple Breeding Populations and Signs of Adaptive Divergence in the South Pacific Amandine D. Marie 1,2 * † , Brian L. Stockwell 1† and Ciro Rico 1,3 * 1 School of Marine Studies, Molecular Analytics Laboratory (MOANA LAB), Faculty of Science Technology and Environment, The University of the South Pacific, Laucala Campus, Suva, Fiji, 2 ESE, Ecology and Ecosystem Health, Agrocampus-Ouest, INRA, Rennes, France, 3 Instituto de Ciencias Marinas de Andalucía (ICMAN), Consejo Superior de Investigaciones Científicas, Campus Universitario Río San Pedro, Cádiz, Spain Shark species have undergone drastic population declines in recent decades due to overfishing and habitat destruction; thus, establishing connectivity among the populations of various shark species is important to determine the appropriate units and spatial scale for conservation and management, particularly as this group is long- lived with late age of maturation. Consequently, we used DNA variation at 1,317 putatively neutral and 25 potentially adaptive single nucleotide polymorphisms (SNPs) to analyze population genetic structure among 174 unrelated individuals of scalloped hammerhead sharks (Sphyrna lewini ) from the Rewa Delta and the Ba Estuary, where documented aggregations of neonates and young-of-the-year occur in the island of Viti Levu, Republic of Fiji. Results of the pairwise F ST analysis for the neutral loci revealed a small but significant genetic differentiation (F ST : 0.004; P-value = 0.0009). Furthermore, the 25 potentially adaptive loci (i.e., under putative selection) revealed a magnitude of differentiation four times bigger than the estimate obtained using neutral genetic diversity (F ST : 0.017; P-value = 0.0009). Interestingly, population assignment tests, using the neutral SNP data set and two different software packages, Admixture and assignPOP, provided evidence for the existence of up to four genetically differentiated populations among our samples. Assignment probabilities ranged from 0.98 ± 0.01 to 0.81 ± 0.03. Admixture and assignPOP assigned the same individuals to the same putative populations for all sampled neonates. Thus, our results provide unequivocal evidence that adult females from multiple genetically differentiated breeding populations contribute to these juvenile aggregation sites. Keywords: scalloped hammerhead shark, population structure, genetic diversity, kinship analyses, SNPs Frontiers in Marine Science | www.frontiersin.org 1 November 2019 | Volume 6 | Article 718