Diversidade e estrutura genética das tartarugas-oliva,Lepidochelys olivacea (Eschscholtz, 1829), no Atlântico Sudoeste

Abstract

The olive ridley sea turtle (Lepidochelys olivacea) is a marine species with a broad circumglobal distribution, considered one of the most abundant worldwide and classified as "Vulnerable" by both the IUCN and National Species Red List. In Brazil, its reproduction is primarily concentrated between the states of Sergipe, Bahia, and Espírito Santo, while foraging areas are utilized along the entire coast. The present study investigated the connectivity and genetic diversity of olive ridley turtle populations in nesting areas and feeding aggregations in the Southwest Atlantic. Through the analysis of seven microsatellite markers, we identified significant patterns of genetic differentiation between the breeding and feeding areas despite the low and similar genetic diversity values observed. Comparison with other populations of the species globally revealed lower genetic diversity in Brazilian olive ridley turtles compared to other Atlantic and, particularly, Indo-Pacific populations. Additionally, the genetic diversity of the Brazilian nesting population was the lowest, even lower than that found in leatherback turtles (Dermochelys coriacea) that nest on the coast of Espírito Santo and are classified as Critically Endangered. Although we detected evidence of subtle genetic structuring among the different nesting sites in Brazil, we did not observe a clear genetic separation between nesting and feeding areas, nor between the different feeding areas sampled. Despite the difficulty in determining the origin of individuals in the foraging areas, this study allowed us to infer valuable information about gene flow along the Brazilian coast. In summary, this research represents a significant advancement in understanding the genetic dynamics of olive ridley turtle populations in the Southwest Atlantic, providing a foundation for future investigations on a broader scale and for the development of more effective management and conservation strategies aligned with the species' movement patterns