Low Diversity and Strong Genetic Structure Between Feeding and Nesting Areas in Brazil for the Critically Endangered Hawksbill Sea Turtle

Thyara Noely Simões,Juliede Nonato Neves,Rita Mascarenhas,Elza Thaynara Cardoso De Menezes Assis,Vivian Chimendes Da Silva Neves,Mirco Solé,Alesandro Souza Santos,Ednilza Maranhão Dos Santos,Fernanda Amato Gaiotto,Werlanne Mendes De Santana Magalhães,Marco Antônio Costa,Waltyane Alves Gomes Bonfim

doi:10.3389/fevo.2021.704838

Abstract

Marine turtle nesting areas are characterized by receiving several females every year. The species Eretmochelys imbricata, known as hawksbill turtle is listed as Critically Endangered by the IUCN, and has been the target of studies on genetic structure and population diversity in nesting areas. Therefore, this study aimed to analyze the genetic diversity and haplotype composition of populations sampled in nesting areas from the coast of northeastern Brazil based on the mtDNA D-loop region. We used genetic information and compared it with data from feeding areas available in public databases. We recorded a total of six exclusive haplotypes in the nesting areas and 27 exclusive haplotypes for the feeding areas. The H_1 haplotype was shared in all nesting areas. The turtles of these regions had a low diversity and a genetic structure composed of five divergent groups separating the reproductive areas from the ones of feeding areas. Positive and significant geographical distance relationships were also recorded with FST values (r = 0.2302, p = 0.007). Our results revealed that hawksbill turtles from reproductive areas comprise a single population that needs management strategies to protect the threatened species, in addition to providing information that contributes to future actions for the species conservation.

Highlights

Five species of sea turtles are distributed along the Brazilian coastline and all of them have been categorized under some level of extinction threat (Santos et al, 2013)
The 15 areas analyzed revealed a total of 33 haplotypes for E. imbricata, highlighting the largest number (13) found in Puerto Rico (PUR), these were registered in the literature for beaches in Mexico, Brazil, Florida, Caribbean and Cuba (Blumenthal et al, 2009; Richardson et al, 2009; Vilaça et al, 2013; Wood et al, 2013; Gorham et al, 2014; Proietti et al, 2014; Cazabon-Mannette et al, 2016; PérezBermúdez et al, 2017; Labastida-Estrada et al, 2019)
Our work revealed that nesting areas of E. imbricata along the Brazilian coast show low haplotypic diversity, with the presence of exclusive haplotypes

Summary

Introduction

Five species of sea turtles are distributed along the Brazilian coastline and all of them have been categorized under some level of extinction threat (Santos et al, 2013). The hawksbill sea turtle Eretmochelys imbricata (Linnaeus, 1766) is classified as Critically Endangered (IUCN, 2008). The species E. imbricata has a circumglobally distribution in tropical and subtropical waters. Genetic Structure the Hawksbill Turtle in the Atlantic, Indian and Pacific Oceans (Pritchard and Mortimer, 1999; LeRoux et al, 2012). Previous research revealed that the populations of E. imbricata are concentrated mainly in the Eastern Atlantic Ocean and the Caribbean (Marcovaldi et al, 2007; Vilaça et al, 2013). Hawksbill turtles feed preferentially on sponges, and like other sea turtles, they have a life cycle with a migratory habit between rookeries and feeding areas and show philopatric behavior (Wallace et al, 2010; Putman et al, 2014)

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