Integrating morphological and genetic data at different spatial scales in a cosmopolitan marine turtle species: challenges for management and conservation

Abstract

<jats:title>Abstract</jats:title> <jats:p>Patterns of genetic structure in highly mobile marine vertebrates may be accompanied by phenotypic variation. Most studies in marine turtles focused on population genetic structure have been performed at rookeries. We studied whether genetic and morphological variation of the endangered green turtle (Chelonia mydas) is consistent geographically, focusing on foraging grounds. An association between population genetic structure and body shape variation at broad (inter-lineage) and fine (foraging grounds) scales was predicted and analysed using mitochondrial DNA and geometric morphometrics. Although genetic and phenotypic differentiation patterns were congruent between lineages, no fine-scale association was found, suggesting adaptive divergence. Connectivity among Pacific foraging grounds found here suggests that temperatures of ocean surface currents may influence the genetic structure of C. mydas on a broad scale. Our results suggest that vicariance, dispersal, life-history traits and ecological conditions operating in foraging grounds have shaped the intraspecific morphology and genetic diversity of this species. Considering a range of geographic and temporal scales is useful when management strategies are required for cosmopolitan species. Integrating morphological and genetic tools at different spatial scales, conservation management is proposed based on protection of neutral and adaptive diversity. This approach opens new questions and challenges, especially regarding conservation genetics in cosmopolitan species.</jats:p>

Green, yellow or black? Genetic differentiation and adaptation signatures in a highly migratory marine turtle

“…Given that C. mydas FGs host individuals with multiple origins [9], a sequential approach was used to define datasets in this study. First, we used an individual-based approach (without prior information) with all individuals and loci to detect how our samples were grouped (PCoA, DAPC and STRUCTURE; see below).…”

“…Given that the results of the individual-based approach grouped samples according to the shape-based morphotypes previously defined by Álvarez-Varas et al . [9,12] (north-central/eastern and south-central/western Pacific morphotypes; electronic supplementary material, figure S1 and S2; see Results), all outlier analyses were carried out using these groups. For the purposes of this paper, the north-central/eastern Pacific morphotype was referred to as ‘black turtle’ and the south-central/western Pacific morphotype as ‘yellow turtle’.…”

“…The formation of the Panama Isthmus separated Atlantic and Pacific C. mydas populations about 3.5 Ma [10,11]. In the Pacific Ocean, an intraspecific clade from the north-central and eastern Pacific regions (NC/EPGL) split from the south-central western Pacific lineage (SC/WPGL) around 0.34 Ma [9,11]. Recent studies using geometric morphometrics showed these main genetic lineages (SC/WPGL and NC/EPGL) vary significantly in their phenotypic traits, including the shape of the head, carapace, plastron and flipper [9,12].…”

“…Conservation and effective management of marine biodiversity require knowledge of the geographical extent of populations and understanding of the population connectivity and life histories [9]. To comprehend the processes that underlie the differences between shape-based morphotypes of the Pacific C. mydas (e.g.…”

Soundscape of green turtle foraging habitats in Fiji, South Pacific

“…Fieldwork was carried out in 2018 at Makogai Island and Yadua Island in Fiji (Fig 1A), tropical South Pacific, where juvenile green turtles from different stocks form foraging aggregations in shallow coastal waters [71,72]. The surface areas of Makogai and Yadua Islands are about 8 km 2 and 15 km 2 , respectively.…”