Topic
Hatchling
About: Hatchling is a research topic. Over the lifetime, 1392 publications have been published within this topic receiving 40689 citations.
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Papers
TL;DR: Sex is fully determined at the time of hatching and naturally irreversible thereafter, and depends on the temperature of egg incubation, which constitutes a possible selective evolutionary advantage of temperature-dependent sex determination (TSD) in alligators in that females become large and sexually mature as early as possible.
Abstract: The factors controlling sexual differentiation in crocodilians are unknown, but heteromorphic sex chromosomes are absent from all species1. Nichols and Chabreck2 speculated that the sex of Alligator mississippiensis was not rigidly determined at the time of hatching but could be influenced by the post-hatching environment. They presented little evidence to support their hypothesis3 (no histological sections of hatchling gonads, no indication of the sex ratio at hatching), and their study failed to take account of habitat preferences of adult male and female alligators4. Here we demonstrate by laboratory and field experiments, that in A. mississippiensis: (1) Sex is fully determined at the time of hatching and naturally irreversible thereafter, and depends on the temperature of egg incubation, temperatures ⩽30 °C producing all females, ⩾34 °C yielding all males. (2) The temperature-sensitive period is between 7 and 21 days of incubation. (3) Natural nests constructed on levees are hotter (34 °C) than those constructed on wet marsh (30 °C), thus the former hatch males and the latter females. (4) The natural sex ratio at hatching is five females to 1 male. (5) Females hatched from eggs incubated at 30 °C weigh significantly more than males hatched from eggs incubated at 34 °C. This weight difference constitutes a possible selective evolutionary advantage of temperature-dependent sex determination (TSD) in alligators in that females become large and sexually mature as early as possible. The occurrence of TSD in alligators has wide-ranging implications for embryological, teratological, molecular, evolutionary, conservation and farming studies as well as for theories relating to the extinction of other Archosaurs.
382 citations
TL;DR: The sex of hatchling map turtles is determined by incubation temperature of eggs in the laboratory as well as in nature, and temperature controls sex differentiation rather than causing a differential mortality of sexes.
Abstract: The sex of hatchling map turtles is determined by incubation temperature of eggs in the laboratory as well as in nature. Temperature controls sex differentiation rather than causing a differential mortality of sexes. Temperature has no effect on sex determination in a soft-shelled turtle.
363 citations
TL;DR: The effects of thermal variance (independent of the mean) on embryonic de- velopment rates and hatchling phenotypes suggest that data from constant-temperature incubation in the laboratory should be interpreted with caution.
Abstract: Mothers may be able to manipulate the phenotypes of their progeny not only via direct pathways (e.g., allocation of nutrients and energy), but also indirectly, by inducing particular developmental pathways through selection of nest sites and thus, incubation conditions. In the field, female skinks (Bassiana duperreyi) in montane southeastern Aus- tralia select nest sites with specific thermal characteristics-especially, a high mean tem- perature and a high diel range in temperature. Monitoring of 14 natural nests throughout most of the incubation period revealed considerable differences among nests in both means and variances of thermal regimes. Laboratory experiments on this species show that both the mean and the variance of incubation temperatures profoundly influence developmental rates (and hence, incubation periods) as well as the body shape, activity levels, thermo- regulatory behavior, and running speeds of the hatchlings. Hence, a female's selection of a particular nest site can substantially modify both the time of emergence of the hatchlings, and the morphology and behavior of her offspring. Even within a single nest, minor dif- ferences among eggs in their depth below the ground surface will directly affect thermal variance, and so may strongly influence rates of embryogenesis and the phenotype of the hatchling. The effects of thermal variance (independent of the mean) on embryonic de- velopment rates and hatchling phenotypes suggest that data from constant-temperature incubation in the laboratory should be interpreted with caution.
326 citations
TL;DR: A recent theoretical model used to predict hatchling sex of reptiles with temperature‐dependent sex determination predicts that sex ratios will be fairly robust to moderate global warming as long as eggs experience substantial daily cyclic fluctuations in incubation temperatures.
Abstract: Incubation temperature influences hatchling phenotypes such as sex, size, shape, color, behavior, and locomotor performance in many reptiles, and there is growing concern that global warming might adversely affect reptile populations by altering frequencies of hatchling phenotypes. Here I overview a recent theoretical model used to predict hatchling sex of reptiles with temperature-dependent sex determination. This model predicts that sex ratios will be fairly robust to moderate global warming as long as eggs experience substantial daily cyclic fluctuations in incubation temperatures so that embryos are exposed to temperatures that inhibit embryonic development for part of the day. I also review studies that examine the influence of incubation temperature on posthatch locomotion performance and growth because these are the traits that are likely to have the greatest effect on hatchling fitness. The majority of these studies used artificial constant-temperature incubation, but some have addressed fluctuating incubation temperature regimes. Although the number of studies is small, it appears that fluctuating temperatures may enhance hatchling locomotor performance. This finding should not be surprising, given that the majority of natural reptile nests are relatively shallow and therefore experience daily fluctuations in incubation temperature.
276 citations
TL;DR: Findings from this study indicate that temporal and spatial variations in moisture and temperature within and among natural nests probably elicit ecologically important variation in size and sex of hatchling snapping turtles.
Abstract: Flexible-shelled eggs of common snapping turtles (Chelydra serpentina) were incubated on two substrates (sand and vermiculite) at each of three temperatures (26.0°, 28.5°, 31.0°C) and three moisture regimes (water potentials initially -150 kPa, -550 kPa, -950 kPa) in a factorial experiment assessing the influence of these variables on the water relations of eggs and the development of embryos. Hatching success was high on wet substrates at 26.0° and 28.5°, but declined at the highest temperature and on drier media. Net absorption of water by viable eggs, duration of incubation by embryos, and size of hatchlings were positively correlated with wetness of substrates and negatively correlated with temperature. Turtles hatching from eggs at 26.0° were males regardless of the wetness of the medium, whereas those emerging from eggs at 28.5° and 31.0° were females. These patterns of response characterized eggs incubated on sand as well as those on vermiculite. Findings from this study indicate that temporal and spatial variations in moisture and temperature within and among natural nests probably elicit ecologically important variation in size and sex of hatchling snapping turtles.
268 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 54 |
| 2024 | 84 |
| 2023 | 143 |
| 2022 | 212 |
| 2021 | 59 |
| 2020 | 41 |