Haplotypic characterization of the olive ridley turtle (Lepidochelys olivacea) in northwest Mexico: the northernmost limit of its distribution

Abstract

Haplotypic characterization of the olive ridley turtle (Lepidochelys olivacea) in northwest Mexico: the northernmost limit of its distribution. The olive ridley sea turtle (L. olivacea) has a pantropical distribution. In the Eastern Pacific, the official limits of its reproduction area are south of the Baja California peninsula and south of Sinaloa, Mexico. Ceuta beach in Elota, Sinaloa, Mexico, has served as a protection site for L. olivacea for over three decades. In this study, the L. olivacea population from Ceuta beach was genetically characterized. Specifically, a 712-bp fragment from the control region of mtDNA was amplified from 32 olive ridley turtles. Eight haplotypes (seven after cutting to ~468 bp) were identified, and these included two novel haplotypes (Lo-T7 and Lo-T8) and five haplotypes that were previously identified in other nesting beaches. The Lo-T2 haplotype was dominant (~60 %) in the samples: h = 0.6048 (± 0.0974) and π = 0.002212 (± 0.001504). Although this study was conducted in the northernmost limit of the olive ridley turtle nesting distribution in the eastern Pacific, the sampled group presents moderate genetic diversity and belongs to a population that, on an evolutionary scale, only recently underwent demographic expansion. Because the olive ridley turtle in the eastern Pacific is considered resilient to environmental variation, nesting area studies in northwest Mexico are necessary.

Large‐scale connectivity, cryptic population structure, and relatedness in Eastern Pacific Olive ridley sea turtles (Lepidochelys olivacea)

“…We observed ten ~ 800 bp haplotypes from 60 turtles nesting at Playa Nancite ( n = 7), Playa Grande ( n = 17), and Playa Ostional ( n = 36; Table 2; Figure 2 and Figure ). Overall haplotype diversity ( H = 0.5657 ± 0.0783 SD ) and nucleotide diversity (π = 0.0014 ± 0.0012 SD ) were comparable to those reported in other studies of Pacific olive ridleys (i.e., Campista León et al, 2019; Jensen et al, 2013; López‐Castro & Rocha‐Olivares, 2005) and did not vary between sites (as suggested by overlapping standard deviations; Table 2).…”

“…There was no evidence that any of the three sites were genetically distinct from each other as determined by pairwise Φ ST ( Φ ST = −0.05–0.00021, p = .37–0.79), pairwise θ ST ( θ ST = −0.03–0.02, p = .61–0.79), and AMOVA (variance explained = −0.21%, F ST =−0.02, p = .65). We compared our data to those published for Mexican olive ridleys (Playa de Ceuta, Sinaloa; Campista León et al, 2019). Pairwise Φ st ( Φ ST = −0.017–0.00571, p = .32–.81), pairwise θ ST ( θ ST = −0.02–0.0043, p = .41–0.78), and AMOVA (variance explained = −0.13%, F ST = 0.001, p = .57) did not suggest divergence between any sampling sites.…”

“…Past phylogeographic studies of olive ridleys have suggested that the Eastern Tropical Pacific population may be no more than 250,000–300,000 years old (Bowen et al, 1997; Jensen et al, 2013). Thus, while at least 14 mtCR haplotypes are reliably documented from Eastern Tropical Pacific olive ridleys (Bowen et al, 1997; Jensen et al, 2013; López‐Castro & Rocha‐Olivares, 2005, Campista León et al, 2019), mutations accrue slowly and it is likely that no haplotypes have established themselves at a level similar to the basal haplotype (Lo46). We were unable to compare our mtCR haplotype data to all studies reporting haplotypes from Eastern Tropical Pacific olive ridleys (i.e., López‐Castro & Rocha‐Olivares, 2005) due to inconsistencies and omissions in naming and reporting of mtCR haplotypes for olive ridleys globally.…”

“…Forward and reverse sequences were trimmed to approximately 800 bps, assembled, and aligned in Geneious v.11 (Kearse et al, 2012) using the CLUSTALW algorithm (Thompson, Gibson, & Higgins, 2003). Olive ridley mtCR haplotypes (~800bp) from prior studies (Bahri, Atmadipoera, & Madduppa, 2018;Bowen et al, 1997;Campista León et al, 2019;Jensen et al, 2013;López-Castro & Rocha-Olivares, 2005;Plot et al, 2012;Revuelta, 2015;Shanker, Ramadevi, Choudhury, Singh, & Aggarwal, 2004) were procured from GenBank and aligned with haplotypes from this study. New and existing haplotypes from Costa Rica were determined using DnaSP 6 (Rozas et al, 2017).…”

Nesting trends of olive ridley sea turtles Lepidochelys olivacea (Testudinata: Cheloniidae) on two beaches in Northwestern Mexico after 30 and 40 years of conservation

“…comm.). Genetic analysis of organisms inhabiting SPC indicated that this rockery has moderate genetic diversity that is very similar (h= 0.6) to that reported by Briseño-Dueñas (1998) for El Verde Camacho (Campista-León et al, 2019); therefore, the importance of monitoring and conserving SPC and the need for more studies at PC are highlighted due to the increasing numbers of nests. In addition, climatic variations, such as the El Niño Southern Oscillation (ENSO), can influence the reproductive success of sea turtles (Santidrián Tomillo et al, 2020); these climatic variations could have no effect or a moderate effect on olive ridley turtle nesting (Ariano-Sánchez et al, 2020;Santidrián Tomillo et al, 2020).…”