Influence of incubation temperature on morphology and locomotion performance of Leatherback (Dermochelys coriacea) hatchlings

Mickelson, L. E. MickelsonL.E.; Downie, J. R.

doi:10.1139/z10-007

Cited by 41 publications

(28 citation statements)

References 28 publications

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“…Direct links between turtle hatchling morphology and fitness have been previously proposed (Ashmore and Janzen 2003;Booth 2006;Burgess et al 2006;Mickelson and Downie 2010;Micheli-Campbell et al 2012;Read et al 2013;Refsnider 2013), and any change in mass as a result of abiotic stress has the potential to affect hatchling survival during their initial journey from the nest to the sea, a stage in which they face a substantial predatory threat from canids, feral/domestic dogs, birds, and ghost crabs. A negative change in marine turtle hatchling mass has been shown to be accompanied by a decrease in flipper size and a decline in terrestrial locomotion performance (Mickelson and Downie 2010). Conversely, Refsnider (2013) showed that an increase in diel thermal variation increased hatchling speed in freshwater turtles.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, although nesting earlier may avoid detrimental mean incubation temperatures, the effects of thermal variance, if independent of the high thermal limits experienced at Alagadi, may persist. Whether hatchlings will be faster, as suggested by Refsnider (2013), or suffer costs to terrestrial locomotion, as suggested by Mickelson and Downie (2010), it is evident that the mechanisms governing this relationship need to be explored in more depth and the fitness consequences and potential adaptive benefits of such a response should be investigated in more detail. This study highlights the need for further research into how different patterns of temperature variation affect reptilian offspring and the mechanisms driving these changes.…”

Section: Discussionmentioning

confidence: 99%

“…However, few studies have looked to quantify the effects of incubation temperature on other characteristics of offspring phenotype, such as size, with a handful having done so in natural nests without manipulation and the use of artificial incubation (Glen et al 2003;Mickelson and Downie 2010;Read et al 2013). Although artificial incubation can undoubtedly enhance our knowledge of the relationship between temperature and phenotype, such studies typically keep temperatures constant or cycled at a constant rate, failing to imitate the natural and unpredictable thermal variance that occurs in the wild.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Thermal Variance on the Phenotype of Marine Turtle Offspring

Horne¹,

Fuller²,

Godley³

et al. 2014

Physiological and Biochemical Zoology

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Temperature can have a profound effect on the phenotype of reptilian offspring, yet the bulk of current research considers the effects of constant incubation temperatures on offspring morphology, with few studies examining the natural thermal variance that occurs in the wild. Over two consecutive nesting seasons, we placed temperature data loggers in 57 naturally incubating clutches of loggerhead sea turtles Caretta caretta and found that greater diel thermal variance during incubation significantly reduced offspring mass, potentially reducing survival of hatchlings during their journey from the nest to offshore waters and beyond. With predicted scenarios of climate change, behavioral plasticity in nest site selection may be key for the survival of ectothermic species, particularly those with temperature-dependent sex determination.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Effect of Thermal Variance on the Phenotype of Marine Turtle Offspring

Horne¹,

Fuller²,

Godley³

et al. 2014

Physiological and Biochemical Zoology

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“…A negative correlation between incubation temperature and sea turtle hatchling size has been documented in all species of sea turtle studied (Hewavisenthi & Parmenter, 2001;Booth et al, 2004;Ischer et al, 2009;Mickelson & Downie, 2010;Booth & Evans, 2011;Maulany et al, 2012a;Read et al, 2012;Wood et al, 2014). Similarly, I found that hatchlings from nests with a T3dm above 34°C…”

Section: Hatchling Size and Massmentioning

confidence: 73%

“…Incubation temperatures that are too low or too high are lethal to the embryo (Hubert, 1985;Miller, 1985), however non-lethal incubation temperatures can also affect a range of hatchling attributes including sex (Valenzuela, 2004;Valenzuela & Lance, 2004), size (Ji et al, 2002;Booth et al, 2004), body shape (Mickelson & Downie, 2010), colouring (Deeming, 2004), metabolic rate (Steyermark & Spotila, 2000), growth rate O'Steen, 1998;Rhen & Lang, 1999;Booth et al, 2004), locomotor performance (Janzen, 1993b;Doody, 1999;Booth et al, 2004), thermoregulatory behaviour (Blumberg et al, 2002;Goodman & Walguarnery, 2007), incidence of deformities and fluctuating asymmetry (Elphick & Shine, 1998;Brana & Ji, 2000;Ji et al, 2002), survival (Billett et al, 1992) and behaviour (Burger, 1998). For these reasons nest temperature and possible changes to nest temperatures are predicted to have a major influence on life history characteristics and viability of oviparous reptile populations.…”

Section: General Introductionmentioning

confidence: 99%

Nest environment and hatchling fitness correlates in the sea turtles Caretta caretta and Natator depressus

Sim¹

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Marine turtles have a complex lifecycle and face threats in both marine and terrestrial environments.Nesting females lay a large number of eggs, very few of which produce hatchlings that survive to reach breeding age. As hatchlings cross the beach, they are exposed to predation, disorientation, dehydration and debris on the beach. When hatchlings enter the water they are exposed to aquatic predators. Hatchlings do not actively avoid predators, or defend themselves, so simply being able to move quickly through this environment would increase their chance of survival. A number of variables can affect hatchling locomotor performance, and this thesis examines three of these: incubation temperature, scute pattern and rookery location in two species of sea turtle, loggerhead (Caretta caretta) and flatback turtles (Natator depressus).The first part of this thesis focuses on scute pattern. Scutes cover the carapace of turtles and tortoises, and each species has a modal pattern. Deviations from this modal pattern are more common in hatchlings than in adult turtles, suggesting that hatchlings with non-modal scute patterns have higher mortality rates, but this hypothesis has not been tested previously. Hatchlings with modal scute patterns were larger and heavier than hatchlings with non-modal scute patterns in both species examined, however this size difference did not translate into a difference in terrestrial locomotor performance. However, N. depressus hatchlings with the modal scute pattern produced more thrust than hatchlings with non-modal scute patterns in the first 40 minutes of swimming, which may give them an advantage over hatchlings with non-modal scute patterns.The second part of this thesis focuses on incubation temperature. Marine turtle eggs successfully incubate within a narrow range of temperatures. Even within the viable developmental temperature range, it has been proposed that hatchlings from eggs incubated close to the thermal tolerance limits may have reduced fitness compared to hatchlings from eggs incubated at intermediate temperatures.In this study, C. caretta hatchlings from hot nests were less likely to emerge from the nest, were smaller, and also performed poorly during crawling and swimming trials compared with hatchlings incubated in moderate temperature nests.The third part of this thesis focuses on differences in hatchling morphology and locomotor performance between two N. depressus rookeries representing two separate 'evolutionarily significant units' (ESUs). Hatchlings at the two sites differed in size, but this size difference did not translate into a difference in either crawling speed or self-righting ability.ii This thesis contributes to our understanding of factors that influence marine turtle hatchling fitness, both environmental and morphological. This information can be used in the monitoring of endangered marine turtle populations.iii DECLARATION BY AUTHOR This thesis is composed of my original work, and contains

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Effect of maternal foraging habitat on offspring quality in the loggerhead sea turtle (Caretta caretta)

Hatase

Omuta²,

Itou

et al. 2018

Ecology and Evolution

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Exploring a trade‐off between quantity and quality of offspring allows differences in the fitness between alternative life histories to be accurately evaluated. We addressed the mechanism that maintains alternative life histories (small oceanic planktivores vs. large neritic benthivores) observed in a loggerhead sea turtle (Caretta caretta) population, which has been suggested to be environmental, based on the lack of genetic structure and a large difference in reproductive output. We examined whether maternal foraging habitat affects offspring quality, by measuring the morphology, emergence success, and righting response of hatchlings following incubation in a common open sand area over the whole nesting season at Yakushima Island, Japan, and by recording early growth and survival of offspring that were reared in a common environment at a Japanese aquarium. Furthermore, we tested whether sea turtles adjust egg size in response to temporal shifts of the incubation environment. There were no significant differences in any hatchling traits between oceanic and neritic foragers (which were classified by stable isotope ratios), except for clutches laid during the warmest period of the nesting season. There were also no significant differences in the growth and survival of offspring originating from the two foragers. The size of eggs from both foragers significantly increased as the season progressed, even though the rookery had heavy rainfall, negating the need to counteract heat‐related reduction in hatchling morphology. In comparison, the sizes of adult body and clutches from both foragers did not vary significantly. The results further support our previous suggestions that the size‐related foraging dichotomy exhibited by adult sea turtles does not have a genetic basis, but derives from phenotypic plasticity. Adjustment in reproductive investment may be associated with: (1) predation avoidance, (2) founder effect, and/or (3) annual variation in egg size.

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Influence of incubation temperature on morphology and locomotion performance of Leatherback (Dermochelys coriacea) hatchlings

Cited by 41 publications

References 28 publications

The Effect of Thermal Variance on the Phenotype of Marine Turtle Offspring

The Effect of Thermal Variance on the Phenotype of Marine Turtle Offspring

Nest environment and hatchling fitness correlates in the sea turtles Caretta caretta and Natator depressus

Effect of maternal foraging habitat on offspring quality in the loggerhead sea turtle (Caretta caretta)

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