Hybridization analysis and haplotypic diversity in Eretmochelys imbricata in Southeastern Brazil

Abstract The hawksbill turtle ( Eretmochelys imbricata ), classified as critically endangered, has a global distribution in tropical and subtropical waters. The Brazilian colony is essential for the species' conservation, as it is the largest remaining nesting population in the South Atlantic. Furthermore, it exhibits the highest hybridization rate worldwide. This study investigated the foraging population in the state of São Paulo (Southeast Brazil), which previously lacked genetic data, using mitochondrial DNA (D-loop) analysis of immature individuals. Hybrids between E. imbricata and Caretta caretta were identified, along with hawksbill haplotypes previously recorded in southern South America and a novel haplotype for the region. The absence of Indo-Pacific haplotypes suggests the influence of the Benguela Current, which reduces genetic diversity compared to the Brazilian Northeast and the Caribbean. The results indicate that the foraging individuals in southern South America predominantly originate from the Brazilian Northeast, with some influence from the Caribbean, highlighting the role of the Brazil Current in the dispersal of hatchlings. These findings emphasize the importance of Southeast Brazil for hawksbill turtle conservation and its relevance to the species' life cycle across different regions.