Population structure of Pacific green turtles: a new perspective from microsatellite DNA variation

Roden, Suzanne E.; Horne, John B.; Jensen, Michael P.; FitzSimmons, Nancy N.; Balazs, George H.; Farman, Richard; Cruce Horeg, Jennifer; Hapdei, Jessy; Heidemeyer, Maike; Jones, T. Todd; Komoroske, Lisa M.; Limpus, Colin J.; Murakawa, Shawn; Piedra, Rotney; Sarti-Martínez, Laura; Summers, Tammy; Tatarata, Miri; Vélez, Elizabeth; Zárate, Patricia; Dutton, Peter H.

doi:10.3389/fmars.2023.1116941

Cited by 3 publications

(7 citation statements)

References 104 publications

(152 reference statements)

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“…As a baseline for genetic assignment and mixed-stock analysis, we drew on the respective mtDNA and microsatellite data of Jensen et al and Roden et al (2023), comprising 20 rookeries throughout the Pacific (Table 1; Figure 1). The samples from these two papers overlap and represent the most up-to-date compilation of new and previously published population genetic datasets for Pacific green turtles.…”

Section: Genetic Baseline Bycatch Collection and Laboratory Processingmentioning

confidence: 99%

“…Tissue for DNA extraction was sampled at sea by trained observers between 1996 and 2017. Storage and transport of tissue collections, as well as laboratory processing, was performed using the same methods as Jensen et al and Roden et al (2023). Final products included a 770-bp fragment of the mitochondrial control region (see Dutton et al, 2014), and ten unlinked microsatellite loci.…”

Section: Genetic Baseline Bycatch Collection and Laboratory Processingmentioning

confidence: 99%

“…each baseline rookery and bycatch collection were calculated in the R package DiveRsity v. 1.9.90 (Keenan et al, 2013). Tests of Hardy-Weinberg equilibrium and the presence of null alleles for microsatellites were performed previously by Roden et al (2023). To help inform the organization of baseline samples into reporting units for genetic assignment and mixed-stock analysis, we computed population-level genetic distances between all pairs of rookeries (microsatellite loci only) using the R package ADEGENET 1.5 (Jombart et al, 2011).…”

Section: Genetic Baseline Bycatch Collection and Laboratory Processingmentioning

confidence: 99%

“…Both types of genetic distance were plotted as networks using the R package NETWORK v. 1.16.1 (Csardi and Nepusz, 2006) for visualization and interpretation. We also took into account the population genetic patterns in Jensen et al and Roden et al (2023) for combining rookeries into reporting units.…”

Section: Genetic Baseline Bycatch Collection and Laboratory Processingmentioning

confidence: 99%

“…Out of ten original microsatellite loci, one was removed because more than 30% of bycatch samples had missing data at this locus. For comparison with Roden et al (2023), the locus removed was A6. Missing genotypes made up 6.2% of the baseline data, with the Coral Sea rookery having the most missing data at 15% and the Revillagigedo Islands having the least at 2.3%.…”

Section: Final Datamentioning

confidence: 99%

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Origins of green turtle fishery bycatch in the central Pacific revealed by mixed genetic markers

et al. 2023

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Longline fishing vessels, such as those that target tuna or billfish, also unintentionally catch endangered marine turtle species on the high seas. The stock composition of this bycatch is often unknown but potentially complex, with individuals coming from many possible origins on an ocean-basin scale. To better understand the stock composition of green turtle (Chelonia mydas) bycatch we obtained 46 turtles, 27-91 cm in curved carapace length, caught by Hawaii- and American Samoa-based pelagic longline fishing vessels across large areas of the North- and South-central Pacific. We genotyped these at nine microsatellite loci and one mitochondrial DNA marker, and used a baseline of 1,043 nesting female green turtles from beaches across the Pacific for population assignment and mixed-stock analysis. By analyzing both marker types jointly we were able to increase power and genetically resolve ten baseline stocks of nesting females with mean self-assignment and simulated accuracies of 75-97%. Above the Equator, green turtle bycatch was composed mostly of individuals from Hawaiian and Eastern Pacific stocks, with a small number from the Western Pacific. Below the Equator, the most common stocks in the bycatch were from Australia and the Coral Sea, American Samoa and French Polynesia, and the Galápagos Islands. Overall, turtles originating from East, West, and Central Pacific breeding populations were major components of the bycatch, suggesting that the geographic ranges of these populations overlap across large tracts of ocean during the pelagic life history stages.

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Section: Genetic Baseline Bycatch Collection and Laboratory Processingmentioning

confidence: 99%

Section: Genetic Baseline Bycatch Collection and Laboratory Processingmentioning

confidence: 99%

Section: Genetic Baseline Bycatch Collection and Laboratory Processingmentioning

confidence: 99%

Section: Genetic Baseline Bycatch Collection and Laboratory Processingmentioning

confidence: 99%

Section: Final Datamentioning

confidence: 99%

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Origins of green turtle fishery bycatch in the central Pacific revealed by mixed genetic markers

et al. 2023

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Hormones and reproductive cycles in turtles

Kuchling,

Owens,

Blanvillain

2024

Hormones and Reproduction of Vertebrates, Volume 3

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Genetic structure and diversity of green turtle (Chelonia mydas) in the Gulf of Thailand

Chomchat,

Klinsawat,

Sirinarumitr

et al. 2024

Vet World

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Background and Aim: The International Union for the Conservation of Nature and Natural Resources lists the green turtle as endangered. Green turtle nesting behavior in the Gulf of Thailand has decreased to <50% of the 1995 level. The population structure of green turtles in the Gulf of Thailand has not yet been studied. This study aimed to characterize the genetic diversity of green turtles in the Gulf of Thailand based on comparisons of mitochondrial DNA (mtDNA) control region with sequences of Indo-Pacific management units (MUs) and rookeries, to investigate population structures, and to explore phylogeographic relationships. Materials and Methods: Blood samples (1 mL each) from 91 stranded green turtles were collected from four parts of the Gulf of Thailand (eastern, upper, central, and lower). The control mtDNA region was amplified by polymerase chain reaction using LCM15382 and H950 primer. The obtained 384-bp or 770-bp sequences were analyzed for haplotype, clade, and haplotype and nucleotide diversities and were used to construct a phylogenetic tree and haplotype network diagram, respectively. In addition, we analyzed genetic differentiation within and among populations of green turtles in the Gulf of Thailand and between green turtles in the Gulf of Thailand and other Indo- Pacific MUs and rookeries. Results: In total, 12 (based on 384 bp) or 13 (based on 770 bp) haplotypes and two clades (clades VII and VIII) were identified, with nine or 10 haplotypes belonging to clade VIII and three haplotypes belonging to clade VII. Of the new haplotypes, four or five were identified and classified as clade VII (two haplotypes, for both fragment lengths) and clade VIII (two or three haplotypes, for 384 bp or 770 bp fragments, respectively). The overall haplotype and nucleotide diversity of green turtles in the Gulf of Thailand were high (0.755 ± 0.039 and 0.01146 ± 0.00248, respectively). Based on the analysis of molecular variance, green turtles in the Gulf of Thailand could be divided into two subpopulations (UC-Eastern Gulf of Thailand [UC-EGT] and lower Gulf of Thailand [LGT]). Comparisons with other MUs and rookeries in the Indo-Pacific showed that UC-EGT was not genetically different from the Peninsular Malaysia and Eastern Taiwan (Lanyu) MUs and the Terrangganu and Mersing rookeries, and LGT were not genetically different from Peninsular Malaysia, Sipadan, Brunei Bay, Eastern Taiwan (Lanyu), Scott Reef and Browse Island, and Gulf of Carpentaria MUs and the Perak, Perhentain Island, Redang, Pahang, and Vietnam rookeries. Conclusion: To the best of our knowledge, this is the first report to identify the haplotypes and clades of green turtles in the Gulf of Thailand and to show that the populations in the Gulf of Thailand not only present high genetic diversity but also have haplotypic endemism. Longer mtDNA fragments (770 bp) increased the resolution of the stock structure. Clade VII is a unique clade not only for Japan but also for Thailand and Malaysia, and CmP82 is a unique haplotype for both the Gulf of Thailand and Malaysia. Conservation and management of these populations are important to preserve the genetic diversity, biological diversity, and evolutionary potential of green turtles in the Gulf of Thailand. Keywords: genetic diversity, green turtle, Gulf of Thailand, phylogeographic.

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Population structure of Pacific green turtles: a new perspective from microsatellite DNA variation

Cited by 3 publications

References 104 publications

Origins of green turtle fishery bycatch in the central Pacific revealed by mixed genetic markers

Origins of green turtle fishery bycatch in the central Pacific revealed by mixed genetic markers

Hormones and reproductive cycles in turtles

Genetic structure and diversity of green turtle (Chelonia mydas) in the Gulf of Thailand

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