Diversidade genética e conservação de tartarugas marinhas do Oceano Atlântico Sudoeste

Abstract

Sea turtles are reptiles with complex life cycles, marked by ontogenetic habitat shifts. They are under a wide range of threats that vary according to their life stage. Thus, the identification and characterization of sea turtle populations is fundamental to clarify variability patterns and how these anthropic pressures can affect these species. The main goals of this study were to evaluate green turtle sex ratios along feeding grounds in the Southwest Atlantic Ocean (SWA), to investigate natal origins of female and male green turtles, to assess the hybridization process among sea turtles from northeastern Brazil and to evaluate temporal variation in green turtle genetic diversity along the SWA and if this variation is related to the recovery of local nesting sites. The control region of the mitochondrial DNA was employed for most genetic analyses, but nuclear loci and mitochondrial short tandem repeats (mtSTR) were also used to assess population structure. Green turtle sex ratios along the SWA were female-skewed and females and males that feed along the coast of northeastern Brazil have slightly divergent natal origins. Temporal variation on green turtle genetic diversity along the SWA was not noticeable. However, it was possible to observe temporal variation in haplotype frequency and natal origins when analysing data from northeastern and southern Brazil independently. Hybridization was observed among four sea turtle species along the coast of Alagoas, northeastern Brazil. Furthermore, a hawksbill specimen had a haplotype typical from Indo-Pacific nesting sites. This study contributes to sea turtle genetic characterization in the SWA and debates important subjects with ecological implications such as the presence of hybridization in sea turtle populations and varying female and male outputs in local nesting sites. Understanding and monitoring these processes is essential to evaluate how sea turtle populations will respond to ongoing environmental pressures, such as climate change and other anthropic threats.