Population genetic diversity of green turtles, Chelonia mydas, in the Mediterranean revisited

Karaman, Sezgin; Türkozan, Oğuz; Carreras, Carlos; Yılmaz, Can; Sönmez, Bektaş; Candan, Onur; Ergene, Serap; Ergene, Mahmut; Uçar, Aşkın Hasan; Ülger, Celal

doi:10.1007/s00227-022-04068-1

Cited by 8 publications

(12 citation statements)

References 36 publications

(69 reference statements)

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“…The specific individual was from the Israel green turtle rookery that is estimated to have only 10-20 nesting females in the last decade (107, 108). However, it is currently unclear if Israel is demographically isolated from other rookeries in the region (108, 109), so further research is needed to understand if inbreeding is a concern only for this nesting aggregation, or the Mediterranean population more broadly. Finally, these findings highlight the utility of ROH even in animals with long generation times, and the importance of using highly contiguous genomes for accurate ROH assessment to inform conservation.…”

Section: Discussionmentioning

confidence: 99%

Divergent sensory and immune gene evolution in sea turtles with contrasting demographic and life histories

Bentley

Carrasco-Valenzuela

Ramos

et al. 2022

Preprint

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Marine turtles represent an ancient lineage of marine vertebrates that evolved from terrestrial ancestors over 100 MYA, yet the genomic basis of the unique physiological and ecological traits enabling these species to thrive in diverse marine habitats remain largely unknown. Additionally, many populations have declined drastically due to anthropogenic activities over the past two centuries, and their recovery is a high global conservation priority. We generated and analyzed high-quality reference genomes for green (Chelonia mydas) and leatherback (Dermochelys coriacea) turtles, representing the two extant marine turtle families (MRCA ~60 MYA). Generally, these genomes are highly syntenic and homologous. Non-collinearity was associated with higher copy numbers of immune, zinc-finger, or olfactory receptor (OR) genes in green turtles. Gene family analyses suggested that ORs related to waterborne odorants have expanded in green turtles and contracted in leatherbacks, which may underlie immunological and sensory adaptations assisting navigation and occupancy of neritic versus pelagic environments, and diet specialization. Microchromosomes showed reduced collinearity, and greater gene content, heterozygosity, and genetic distances between species, supporting their critical role in vertebrate evolutionary adaptation. Finally, demographic history and diversity analyses showed stark contrasts between species, indicating that leatherback turtles have had a low yet stable effective population size, extremely low diversity when compared to other reptiles, and a higher proportion of deleterious variants, reinforcing concern over the persistence of this species under future climate scenarios. These highly contiguous genomes provide invaluable resources for advancing our understanding of evolution and conservation best practices in an imperiled vertebrate lineage.

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Section: Discussionmentioning

confidence: 99%

Divergent sensory and immune gene evolution in sea turtles with contrasting demographic and life histories

Bentley

Carrasco-Valenzuela

Ramos

et al. 2022

Preprint

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Section: Discussionmentioning

confidence: 99%

“…MED3 management unit, including the five beaches analysed in this study, is important for genetic variability because it contains a set of partially connected populations (especially the Samandağ and Alata hubs of connectivity) (Karaman et al, 2022). Samandağ nesting beach connects Alata, north Karpaz, and Israel to the nesting beaches of Akyatan, Kazanlı, Sugözü, and Davultepe (Karaman et al, 2022). The fact that these five beaches have connection hubs for genetic diversity as well as display morphological compatibility, reveals the need for special conservation and management plans.In this context, future body sizes may decrease due to the effects of temperature on the developmental and physiological processes of marine turtles as a result of global climate change (Ohlberger, 2013;Marshall et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…The study area includes Alata, Kazanlı, Akyatan, Sugözü, and Samandağ beaches (Fig. 1), which are major nesting beaches for C. mydas in the MED3 MU (Karaman et al, 2022). The average number of nests for the recent five years on these beaches ranges between 125 and 365 (Casale et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

“…These MUs are Akamas, Alagadi, Israel, and Turkey. A recent study, Karaman et al (2022) extended the abovementioned study and proposed a minimum of 3 MUs for the Mediterranean population. The MUs are MED1 (Akamas and Akdeniz), MED2 (Alagadi), and MED3 (North and South Karpaz, Israel, Samandağ, Akyatan, Sugözü, Kazanlı, Alata, and Davultepe).…”

mentioning

confidence: 96%

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Dichotomy in morphology of the same genetic lineage of green turtles

Sönmez¹,

Mestav²,

Kırbeci³

et al. 2023

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Morphological studies of marine turtles are important to provide insight into changes in their developmental environment. This study aimed to determine green turtles' Chelonia mydas morphological differences within the same genetic lineage in the eastern Mediterranean MED3 management unit and to find the best conversion equations between carapace size. A total of 106 adult green turtles (curved carapace length [CCL] range 79–105 cm) were measured on the five major nesting beaches of the eastern Mediterranean during 2020 and 2021. Morphological differences were tested with PERMANOVA and the relationship among body sizes was tested by linear regression. In the eastern Mediterranean green turtles, the mean CCL and SCL (straight carapace length) were 88.5 cm and 83.5 cm, respectively. There were no statistically significant differences in any of the examined morphological characteristics of green turtles collected from five nesting beaches. In the clustering analysis, however, it was found that all the turtles fell into two distinct groups: larger (> 95.2 cm) and smaller (< 85.2 cm) turtles. As well, the conversion equations between CCL and SCL showed a high coefficient of determination (R2 = 0.938). We suggest that the conversion equations may be applied to all green turtles belonging to this population and nesting in the eastern Mediterranean. Keywords: Chelonia mydas, morphology, conversion equation, K-means, eastern Mediterranean

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A 21‐year recovery trend in green turtle nesting activity: 2002–2022

Sönmez,

Mestav,

Özdilek

2023

Aquatic Conservation

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Long‐term monitoring and conservation are crucial for effective protection, since sea turtles migrate cyclically every 2–3 years and lay multiple nests during a breeding season. Therefore, this study aimed to investigate the long‐term trend of nesting activities of green turtles over a 21‐year period (2002–2022) on Samandağ beach. An early morning survey was conducted every year during both nesting and hatching seasons. The trend analyses in nesting activities were performed using Mann–Kendall and Sen's slope tests together with the augmented Dickey–Fuller stationarity test. The nest count and female abundance increased significantly, whereas clutch size, fecundity, and hatching success tended to decrease insignificantly. The percentage change between the most recent and oldest 3‐year mean nest count and mean female abundance, which is performed to comply with the Red List assessment method used by the International Union for Conservation of Nature Marine Turtle Specialist Group, was 769% and 764% respectively. Samandağ nesting population accounts for one‐third of the Mediterranean's total nest count and one‐fourth of its total female abundance. The decrease in clutch size and fecundity may be due to the recruitment of individuals with smaller body sizes or malnutrition as a result of population growth. There was an increase in the number of dead embryos and a decline in hatching success. This may be explained by density‐dependent population regulation as a result of an increase in the number of nests. It may be argued that adherence to a uniform strategy and the maintenance of continuous protection through collaboration with governmental and non‐governmental organizations with scientifically rigorous methodology are significant factors contributing to the high recovery. This study emphasizes the necessity of adopting a comprehensive conservation approach encompassing both foraging habitats and the significant role played by the population in Samandağ in the proliferation of Mediterranean green turtles.

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Population genetic diversity of green turtles, Chelonia mydas, in the Mediterranean revisited

Cited by 8 publications

References 36 publications

Divergent sensory and immune gene evolution in sea turtles with contrasting demographic and life histories

Divergent sensory and immune gene evolution in sea turtles with contrasting demographic and life histories

Dichotomy in morphology of the same genetic lineage of green turtles

A 21‐year recovery trend in green turtle nesting activity: 2002–2022

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