The impact of sand moisture on the temperature-sex ratio responses of developing loggerhead (Caretta caretta) sea turtles

Lolavar, Alexandra; Wyneken, Jeanette

doi:10.1016/j.zool.2019.125739

Cited by 23 publications

(13 citation statements)

References 55 publications

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“…The hatching success was greater under relative humidity equals to or higher than 69% for E. imbricata and from 64% onward for L. olivacea. A similar result was obtained for nests of C. caretta in Florida (USA) (Lolavar & Wyneken 2020). We recorded an increase in hatching success from the inflection point of 28.5 °C to 31 °C for E. imbricata and between 25 °C and 28 °C for L. olivacea.…”

Section: Discussionsupporting

confidence: 87%

Long-term monitoring of marine turtle nests in northeastern Brazil

et al. 2021

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This study monitored marine turtle nests in a region known as the Potiguar Basin, which stretches from the northern region of Rio Grande do Norte State (5°4’1.15” S, 36°4’36.41” W) to eastern Ceará State (4°38’48.28” S, 37°32’52.08” W) in Brazil. We collected data from January 2011 to December 2019 to identify species of sea turtles that spawn in the basin, to analyze the nesting spatial-temporal pattern and nests characteristics, and to record effects of environmental and anthropic factors on nests. A field team examined sea turtle tracks and nests signs. Turtle clutches were monitored daily until hatchings emerged from the nests. We monitored nests of hawksbill (Eretmochelys imbricata; n = 238) and olive Ridley turtles (Lepidochelys olivacea; n = 103). The nesting season for E. imbricata occurred between December and May and for L. olivacea from March to August. Hawksbills had clutch size, incubation time, number of unhatched eggs, and dead hatchlings higher than olive Ridley turtles; nevertheless, they presented lower hatching success. Precipitation between 0 and 22 mm and relative humidity (RH) higher than 69% increased the hatching success rate for E. imbricata; however, rainfall above 11 mm and RH 64% had the same effect for L. olivacea. Signs of egg theft and human presence (e.g. vehicle traffic and plastic residues on the beach) were recorded and are considered threats to nests. The results of our long-term monitoring study in the Potiguar Basin provide basis for the implementation of mitigation measures and adoption of management policies at nesting beaches in this Brazilian region.

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Section: Discussionsupporting

confidence: 87%

Long-term monitoring of marine turtle nests in northeastern Brazil

et al. 2021

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“…Moisture indirectly alters nest temperatures (Lolavar and Wyneken 2015 ; Sifuentes-Romero et al 2017b ) and restricts oxygen availability (Cedillo-Leal et al 2017 ), with potentially other direct, unknown mechanisms (Lolavar and Wyneken 2017 ). Potentially, moisture concentrations may alter the width of the transitional range of temperatures, as well as the upper and lower limits (Lolavar and Wyneken 2020 ). Moisture does not appear to modulate the pivotal temperature (Lolavar and Wyneken 2020 ).…”

Section: Effects Of Incubation Conditions On Hatchling Phenotypesmentioning

confidence: 99%

“…Potentially, moisture concentrations may alter the width of the transitional range of temperatures, as well as the upper and lower limits (Lolavar and Wyneken 2020 ). Moisture does not appear to modulate the pivotal temperature (Lolavar and Wyneken 2020 ).…”

Section: Effects Of Incubation Conditions On Hatchling Phenotypesmentioning

confidence: 99%

A review of the effects of incubation conditions on hatchling phenotypes in non-squamate reptiles

Gatto

Reina

2022

J Comp Physiol B

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Developing embryos of oviparous reptiles show substantial plasticity in their responses to environmental conditions during incubation, which can include altered sex ratios, morphology, locomotor performance and hatching success. While recent research and reviews have focused on temperature during incubation, emerging evidence suggests other environmental variables are also important in determining hatchling phenotypes. Understanding how the external environment influences development is important for species management and requires identifying how environmental variables exert their effects individually, and how they interact to affect developing embryos. To address this knowledge gap, we review the literature on phenotypic responses in oviparous non-squamate (i.e., turtles, crocodilians and tuataras) reptile hatchlings to temperature, moisture, oxygen concentration and salinity. We examine how these variables influence one another and consider how changes in each variable alters incubation conditions and thus, hatchling phenotypes. We explore how incubation conditions drive variation in hatchling phenotypes and influence adult populations. Finally, we highlight knowledge gaps and suggest future research directions.

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“…For instance, the relationship between rainfall and sex ratios has generally been attributed to the cooling effect of rain on the temperature of nesting substrate thanks to evaporative cooling (Godfrey et al, 1996 ; Houghton et al, 2007 ; Lolavar & Wyneken, 2015 ; Matsuzawa et al, 2002 ). An argument has recently also been made to suggest that humidity itself has an effect on sex ratios beyond that of temperature alone (Lolavar & Wyneken, 2017 , 2020 ). While these studies have not yet robustly demonstrated the effect of humidity on TSD, they do illustrate several points.…”

Section: Tsd Patterns and Environmental Covariatesmentioning

confidence: 99%

Effects of global warming on species with temperature‐dependent sex determination: Bridging the gap between empirical research and management

Lockley

Eizaguirre

2021

Evolutionary Applications

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Global warming could threaten over 400 species with temperature-dependent sex determination (TSD) worldwide, including all species of sea turtle. During embryonic development, rising temperatures might lead to the overproduction of one sex and, in turn, could bias populations' sex ratios to an extent that threatens their persistence. If climate change predictions are correct, and biased sex ratios reduce population viability, species with TSD may go rapidly extinct unless adaptive mechanisms, whether behavioural, physiological or molecular, exist to buffer these temperaturedriven effects. Here, we summarize the discovery of the TSD phenomenon and its still elusive evolutionary significance. We then review the molecular pathways underpinning TSD in model species, along with the hormonal mechanisms that interact with temperatures to determine an individual's sex. To illustrate evolutionary mechanisms that can affect sex determination, we focus on sea turtle biology, discussing both the adaptive potential of this threatened TSD taxon, and the risks associated with conservation mismanagement.

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The impact of sand moisture on the temperature-sex ratio responses of developing loggerhead (Caretta caretta) sea turtles

Cited by 23 publications

References 55 publications

Long-term monitoring of marine turtle nests in northeastern Brazil

Long-term monitoring of marine turtle nests in northeastern Brazil

A review of the effects of incubation conditions on hatchling phenotypes in non-squamate reptiles

Effects of global warming on species with temperature‐dependent sex determination: Bridging the gap between empirical research and management

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