DOI: 10.5061/dryad.dncjsxmbq
title: Data from: Local adaptation may help mitigate feminisation of sea turtle populations globally

description: 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.
description: # Data from: Local adaptation may help mitigate feminisation of sea turtle
 populations globally Dataset DOI:
 [10.5061/dryad.dncjsxmbq](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](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.