Data from: Local adaptation may help mitigate feminisation of sea turtle populations globally
Data files
Sep 12, 2025 version files 112.50 KB
Abstract
Climate warming currently threatens many species with extinction, particularly those with a limited capacity for adaptation. Sea turtles have temperature-dependent sex determination, whereby female hatchlings are produced at warmer incubation temperatures, and hence climate warming might cause the feminisation of populations. Recent evidence suggests that climate warming will outpace the ability of turtles to adapt through phenological shifts in nesting. Here, we examine 138 published estimates for hatchling sex ratios spanning the 7 sea turtle species and all ocean basins. We evaluate whether turtles have the capacity to adapt to warming temperatures through local adaptations of the pivotal temperature at which they produce a balanced amount of male and female hatchlings. We show that at warmer sites, lower proportions of female hatchlings are produced than expected from generalised sex ratio versus incubation temperature relationships that have been previously used across all sea turtle species. This points to local adaptation of the pivotal temperature (i.e., the temperature at which a balanced hatchling sex ratio is produced) as evidenced by an analysis of 33 pivotal temperatures recorded at sites around the world, that showed generally higher pivotal temperatures at warmer sites, confirming previous work. These findings point to local adaptation of the pivotal temperatures, which could help the production of male hatchlings at warmer sites and so assist with population viability. These results suggest that sea turtle hatchling sex ratio is more resilient to climate change than previously thought.
Dataset DOI: 10.5061/dryad.dncjsxmbq
Description of the data and file structure
Local adaptation may help mitigate feminisation of sea turtle populations globally
We assembled a global database of sea turtle hatchling sex ratios, pivotal temperatures, and nesting seasons from the published literature. We evaluate whether turtles have the capacity to adapt to warming temperatures through local adaptations of the pivotal temperature at which they produce a balanced amount of male and female hatchlings.
Files and variables
File: 2025_Tromp_GCB_Local-adaptation_S1_Hatchling-sex-ratio.csv
Description: Sea turtle hatching sex ratios (% female) for key nesting sites around the globe with derived monthly air temperatures (ICOADS), representing the thermal conditions during the nesting period.
Variables
- First Author: Last name of the first author from the reference.
- Year: Year that the reference was published.
- Site: Location from which the hatchling sex ratio (% female) was derived.
- Region RMU 2023: Regional management units for marine turtles as defined by Wallace et al., 2023 (https://doi.org/10.3354/esr01243) .
- Species: Abbreviation of the first letter from the genus and species name of the seven marine turtles; loggerhead (Caretta caretta), green (Chelonia mydas), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea), Kemp’s ridley (Lepidochelys kempii) and flatback (Natator depressus) turtles.
- Latitude: Latitude in decimal degrees.
- Longitude: Longitude in decimal degrees.
- Sex ratio (%F): Hatchling sex ratio in % female.
- Reference: Reference from which the hatchling sex ratio was derived.
File: 2025_Tromp_GCB_Local-adaptation_S2_Pivotal-temperature.csv
Description: Sea turtle pivotal temperatures of key nesting sites around the globe with derived monthly air temperatures (ICOADS), representing the thermal conditions during the nesting period. Pivotal temperatures were either experimentally determined in a temperature-controlled environment (laboratory) or calculated in-situ (field study).
Variables
- First author: Last name of the first author from the reference.
- Year: Year that the reference was published.
- Site: Location from which the pivotal temperature (C) was derived.
- Species: Abbreviation of the first letter from the genus and species name of the seven marine turtles; loggerhead (Caretta caretta), green (Chelonia mydas), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea), Kemp’s ridley (Lepidochelys kempii) and flatback (Natator depressus) turtles.
- Study type: The sampling approach taken (field or laboratory study).
- Latitude: Latitude in decimal degrees.
- Longitude: Longitude in decimal degrees.
- Reported pivotal temperature (C): Pivotal temperature reported in the reference.
- Pivotal temperature (C): Single value derived from the reported reference.
- Reference: Reference from which the pivotal temperature was derived.
File: 2025_Tromp_GCB_Local-adaptation_S3_Nesting-season.xlsx
Description: Sea turtle nesting season of key nesting sites around the globe. Months highlighted in bold indicate the peak of nesting season as given in the reference. Empty cells indicate that nesting wasn't observed. References are provided on the second sheet.
Variables
- Site: Location from which the nesting season was derived.
- Species: Abbreviation of the first letter from the genus and species name of the seven marine turtles; loggerhead (Caretta caretta), green (Chelonia mydas), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea), Kemp’s ridley (Lepidochelys kempii) and flatback (Natator depressus) turtles.
- January – First month of the year.
- February – Second month of the year.
- March – Third month of the year.
- April – Fourth month of the year.
- May – Fifth month of the year.
- June – Sixth month of the year.
- July – Seventh month of the year.
- August – Eighth month of the year.
- September – Ninth month of the year.
- October – Tenth month of the year.
- November – Eleventh month of the year.
- December – Twelfth and final month of the year.