Mitochondrial DNA Profiling to Combat the Illegal Trade in Tortoiseshell Products

LaCasella, Erin L.; Jensen, Michael P.; Hof, Christine A. Madden; Bell, Ian; Frey, Amy; Dutton, Peter H.

doi:10.3389/fmars.2020.595853

Cited by 15 publications

(10 citation statements)

References 37 publications

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“…To isotopically distinguish two separate habitats, we referenced hawksbill skin stable isotope values previously published and from the current study to help characterize the mangrove estuary (Bahía de Jiquilisco, Wedemeyer-Strombel et al, 2021) and the rocky reef / ocean (Punta Amapala, current study) as two isotopically distinct locations (inside or outside estuary). In Wedemeyer-Strombel et al (2021), skin from juvenile (<65 cm CCL) hawksbills captured in Bahía de Jiquilisco had stable carbon isotope values that ranged from ca.…”

Section: Stable Isotope Analysismentioning

confidence: 97%

Tracking movements and growth of post-hatchling to adult hawksbill sea turtles using skeleto+iso

Tomaszewicz

Liles²,

Avens

et al. 2022

Front. Ecol. Evol.

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In the eastern Pacific Ocean, hawksbill sea turtles (Eretmochelys imbricata) are adapted to use coastal habitats and ecosystems uncharacteristic of most other sea turtles. Once considered extirpated from this region, hawksbills had sought refuge in estuaries, nesting on muddy banks among the tangles of mangrove roots. This population is at high risk of bycatch during fishing efforts in the estuaries (blast fishing) and adjacent coastal rocky reefs (gillnets), and is further impacted by habitat degradation from coastal development and climate change. The conservation and population recovery of hawksbills in this region is highly dependent on management actions (e.g., nest relocation, habitat protection, bycatch mitigation), and a better understanding of how hawksbills use and move between distinct habitats will help prioritize conservation efforts. To identify multi-year habitat use and movement patterns, we used stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of skin and bone growth layers to recreate movements between two isotopically distinct habitats, a nearshore rocky reef and a mangrove estuary, the latter distinguishable by low δ13C and δ15N values characteristic of a mangrove-based foodweb. We applied skeletochronology with sequential δ13C and δ15N analysis of annual growth layers, “skeleto+iso,” to a dataset of 70 hawksbill humeri collected from coastal El Salvador. The results revealed at least two unique habitat-use patterns. All turtles, regardless of stranding location, spent time outside of the mangrove estuaries during their early juvenile years (< 35 cm curved carapace length, CCL, age 0–5), showing that an oceanic juvenile stage is likely for this population. Juveniles ca. > 35 cm then began to recruit to nearshore areas, but showed divergent habitat-use as some of turtles occupied the coastal rocky reefs, while others settled into the mangrove estuaries. For turtles recruiting to the estuaries, settlement age and size ranged from 3 to 13 years and 35–65 cm CCL. For the adult turtles, age-at-sexual-maturity ranged from 16 to 26 years, and the maximum reproductive longevity observed was 33 years. The skeleto+iso also showed that adult hawksbills have long-term habitat fidelity, and the results demonstrate the importance of both mangrove estuary and nearshore rocky reefs to the conservation of hawksbills in the eastern Pacific.

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Section: Stable Isotope Analysismentioning

confidence: 97%

Tracking movements and growth of post-hatchling to adult hawksbill sea turtles using skeleto+iso

Tomaszewicz

Liles²,

Avens

et al. 2022

Front. Ecol. Evol.

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“…The hawksbill turtle ( Eretmochelys imbricata ) is a circumtropically distributed marine reptile with nesting colonies scattered across the Atlantic and Indo-Pacific. In the past, their numbers have dwindled for many of the same reasons as other sea turtle species, such as human harvesting for food, and fisheries bycatch, but also for being disproportionately targeted by the international shell trade, which is illegally ongoing in many countries [ 23 ]. Some hawksbill populations have shown signs of recent recovery [ 19 , 20 ] in response to management interventions, but others continue to decline in spite of efforts to protect their remaining numbers [ 24 ].…”

Section: Introductionmentioning

confidence: 99%

Non-random mating within an Island rookery of Hawaiian hawksbill turtles: demographic discontinuity at a small coastline scale

et al. 2023

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Hawksbill sea turtles ( Eretmochelys imbricata ) from the Hawaiian archipelago form a small and genetically isolated population, consisting of only a few tens of individuals breeding annually. Most females nest on the island of Hawai'i, but little is known about the demographics of this rookery. This study used genetic relatedness, inferred from 135 microhaplotype markers, to determine breeding sex-ratios, estimate female nesting frequency and assess relationships between individuals nesting on different beaches. Samples were collected during the 2017 nesting season and final data included 13 nesting females and 1002 unhatched embryos, salvaged from 41 nests, of which 13 had no observed mother. Results show that most females used a single nesting beach laying 1–5 nests each. From female and offspring alleles, the paternal genotypes of 12 breeding males were reconstructed and many showed high relatedness to their mates. Pairwise relatedness of offspring revealed one instance of polygyny but otherwise suggested a 1 : 1 breeding-sex ratio. Relatedness analysis and spatial-autocorrelation of genotypes indicate that turtles from different nesting areas do not regularly interbreed, suggesting that strong natal homing tendencies in both sexes result in non-random mating across the study area. Complexes of nearby nesting beaches also showed unique patterns of inbreeding across loci, further indicating that Hawaiian hawksbill turtles have demographically discontinuous nesting populations separated by only tens of km.

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“…Traditionally, conservation genetic studies have relied on genetic markers such as mitochondrial control regions or nuclear microsatellites (Jensen et al, 2013). A recently announced project aimed at constructing a database of hawksbill mitochondrial DNA sequences was initiated to track illegally traded hawksbill shells (LaCasella et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Population genomic analysis reveals high inbreeding in a Hawksbill turtle population nesting in Singapore

Tiong,

Dacanay,

Uchida

et al. 2023

Preprint

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Seven species of marine turtles remain in a world currently threatened by anthropogenic activities and climate change, standing at the precipice of extinction. Urgent conservation endeavours are imperative to safeguard their survival and preserve the biodiversity of marine ecosystems. Yet, genetic studies on these turtles have leaned on restricted genetic markers, such as the mitochondrial control region. The markers could provide incomplete or biased estimations of genetic diversity and population structure, thereby limiting precise conservation strategies. Here, we have generated ade novogenome assembly and high-quality whole-genome population datasets from hawksbill turtles nesting and foraging in Singapore. This initiative aims to contribute to unbiased, fine-resolution genetic data on the species, conducting a comprehensive population genomic study. Our analysis results demonstrated a remarkable enhancement in genetic markers. While we identified five different haplotypes defined by five variants within 69 mitochondrial control region sequences, the analysis of 35 whole genome sequences uncovered approximately 12 million single nucleotide polymorphisms (SNPs). Within the Singapore hawksbill turtle population, our whole-genome analysis revealed a pronounced degree of inbreeding, with most samples sharing at least a first cousin relationship. Furthermore, within a multiple-paternity nest, we identified related parents. Additionally, our inference of demographic history underscored the impact of past climate change on the decreasing hawksbill turtle population. We believe this pioneering study will substantially enhance the field of conservation genetic study of marine turtles.

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Mitochondrial DNA Profiling to Combat the Illegal Trade in Tortoiseshell Products

Cited by 15 publications

References 37 publications

Tracking movements and growth of post-hatchling to adult hawksbill sea turtles using skeleto+iso

Tracking movements and growth of post-hatchling to adult hawksbill sea turtles using skeleto+iso

Non-random mating within an Island rookery of Hawaiian hawksbill turtles: demographic discontinuity at a small coastline scale

Population genomic analysis reveals high inbreeding in a Hawksbill turtle population nesting in Singapore

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