Embryonic temperature determines adult sexuality in a reptile

Gutzke, William H. N.; Crews, David

doi:10.1038/332832a0

Cited by 140 publications

(83 citation statements)

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“…In practice, the logistical obstacles to such a study are so great that we were forced to rely on simulation of natural habitats using large field enclosures, and in the present study we have examined only one subset of fitness differentials: those that are evident prior to sexual maturation. This is an important limitation, because some sex-specific effects of incubation temperature might become apparent only after maturation (Gutzke and Crews 1988). Nonetheless, juvenile life is the phase of life history closest to incubation, and thus we might expect that any effects of incubation temperature would be most obvious at this time.…”

Section: Discussionmentioning

confidence: 99%

“…However, the adaptive significance of TSD remains unclear for reptiles, as it does for most phylogenetic lineages of organisms. The Charnov-Bull model is by far the most widely supported in published literature, but this acceptance reflects its overall plausibility-especially, consistency of its assumptions with known aspects of reptile biology-rather than specific experimental evidence (Gutzke and Crews 1988;Janzen 1995;Freedberg et al 2004). Attempts to empirically test the Charnov-Bull model have been impeded by at least three factors:…”

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confidence: 99%

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The Adaptive Significance of Temperature-Dependent Sex Determination: Experimental Tests With a Short-Lived Lizard

Warner

Shine

2005

Evolution

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Abstract. Why is the sex of many reptiles determined by the temperatures that these animals experience during embryogenesis, rather than by their genes? The Charnov-Bull model suggests that temperature-dependent sex determination (TSD) can enhance maternal fitness relative to genotypic sex determination (GSD) if offspring traits affect fitness differently for sons versus daughters and nest temperatures either determine or predict those offspring traits. Although potential pathways for such effects have attracted much speculation, empirical tests largely have been precluded by logistical constraints (i.e., long life spans and late maturation of most TSD reptiles). We experimentally tested four differential fitness models within the Charnov-Bull framework, using a short-lived, early-maturing Australian lizard (Amphibolurus muricatus) with TSD. Eggs from wild-caught females were incubated at a range of thermal regimes, and the resultant hatchlings raised in large outdoor enclosures. We applied an aromatase inhibitor to half the eggs to override thermal effects on sex determination, thus decoupling sex and incubation temperature. Based on relationships between incubation temperatures, hatching dates, morphology, growth, and survival of hatchlings in their first season, we were able to reject three of the four differential fitness models. First, matching offspring sex to egg size was not plausible because the relationship between egg (offspring) size and fitness was similar in the two sexes. Second, sex differences in optimal incubation temperatures were not evident, because (1) although incubation temperature influenced offspring phenotypes and growth, it did so in similar ways in sons versus daughters, and (2) the relationship between phenotypic traits and fitness was similar in the two sexes, at least during preadult life. We were unable to reject a fourth model, in which TSD enhances offspring fitness by generating seasonal shifts in offspring sex ratio: that is, TSD allows overproduction of daughters (the sex likely to benefit most from early hatching) early in the nesting season. In keeping with this model, hatching early in the season massively enhanced body size at the beginning of the first winter, albeit with a significant decline in probability of survival. Thus, the timing of hatching is likely to influence reproductive success in this short-lived, early maturing species; and this effect may well differ between the sexes.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

The Adaptive Significance of Temperature-Dependent Sex Determination: Experimental Tests With a Short-Lived Lizard

Warner

Shine

2005

Evolution

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“…In the case of temperature-dependent sex determination (TSD), gonadal sex is permanently determined primarily by incubation temperature during the middle third of embryonic development Paukstis 1991, Mrosovsky andPieau 1991). In animals with TSD, developmental temperature elicits important individual phenotypes that are both ecologically significant and subject to selection (Conover 1984, Gutzke and Crews 1988, Janzen 1995, Shine 1999, Deeming 2004, Warner and Shine 2008. Moreover, abiotic factors such as climate can have strong impacts on overall sex ratio of emergent hatchlings (cohort sex ratio) and, potentially, on population ecology and dynamics (Janzen 1994a, Girondot et al 1998, 2004, Mitchell et al 2008, Tucker et al 2008, Wapstra et al 2009 thermally extreme years that produces only one sex (e.g., males) has the potential to eliminate the population Bulmer 1989, Janzen 1994a).…”

Section: Introductionmentioning

confidence: 99%

Climate and predation dominate juvenile and adult recruitment in a turtle with temperature‐dependent sex determination

Schwanz

Spencer

Bowden

et al. 2010

Ecology

123

156

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Conditions experienced early in life can influence phenotypes in ecologically important ways, as exemplified by organisms with environmental sex determination. For organisms with temperature-dependent sex determination (TSD), variation in nest temperatures induces phenotypic variation that could impact population growth rates. In environments that vary over space and time, how does this variation influence key demographic parameters (cohort sex ratio and hatchling recruitment) in early life stages of populations exhibiting TSD? We leverage a 17-year data set on a population of painted turtles, Chrysemys picta, to investigate how spatial variation in nest vegetation cover and temporal variation in climate influence early lifehistory demography. We found that spatial variation in nest cover strongly influenced nest temperature and sex ratio, but was not correlated with clutch size, nest predation, total nest failure, or hatching success. Temporal variation in climate influenced percentage of total nest failure and cohort sex ratio, but not depredation rate, mean clutch size, or mean hatching success. Total hatchling recruitment in a year was influenced primarily by temporal variation in climate-independent factors, number of nests constructed, and depredation rate. Recruitment of female hatchlings was determined by stochastic variation in nest depredation and annual climate and also by the total nest production. Overall population demography depends more strongly on annual variation in climate and predation than it does on the intricacies of nest-specific biology. Finally, we demonstrate that recruitment of female hatchlings translates into recruitment of breeding females into the population, thus linking climate (and other) effects on early life stages to adult demographics. Abstract. Conditions experienced early in life can influence phenotypes in ecologically important ways, as exemplified by organisms with environmental sex determination. For organisms with temperature-dependent sex determination (TSD), variation in nest temperatures induces phenotypic variation that could impact population growth rates. In environments that vary over space and time, how does this variation influence key demographic parameters (cohort sex ratio and hatchling recruitment) in early life stages of populations exhibiting TSD? We leverage a 17-year data set on a population of painted turtles, Chrysemys picta, to investigate how spatial variation in nest vegetation cover and temporal variation in climate influence early life-history demography. We found that spatial variation in nest cover strongly influenced nest temperature and sex ratio, but was not correlated with clutch size, nest predation, total nest failure, or hatching success. Temporal variation in climate influenced percentage of total nest failure and cohort sex ratio, but not depredation rate, mean clutch size, or mean hatching success. Total hatchling recruitment in a year was influenced primarily by temporal variation in climate-independent factors, number of...

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“…Após a diferenciação sexual as gônadas produzem hormônios esteróides que precipitam uma cascata de eventos que culminará nas diferenças entre os indivíduos adultos (Gutzke & Crews, 1988). A influência da temperatura de incubação não se restringe apenas à fase embrionária, estendendo-se às fases posteriores do desenvolvimento, com reflexos no modo de vida dos répteis adultos.…”

Section: Influência Da Temperatura Dos Ninhos No Desenvolvimento Dos unclassified

Efeitos de Fatores Ambientais na Reprodução de Tartarugas

Júnior

2009

Acta Amaz.

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ResumoPara as espécies de tartaruga que apresentam a determinação sexual dependente da temperatura da incubação o local e o momento da desova, exercem influências que vão além da definição do sexo dos embriões. A influência do local da desova se estende a todo o desenvolvimento embrionário afetando o comportamento e o tamanho dos filhotes. O momento em que ocorre a desova trará conseqüências ao ambiente térmico dos ninhos à medida que a temperatura e a umidade variam ao longo do ano. A umidade será decisiva nas trocas hídricas e gasosas entre os ovos e o meio afetando a absorção do vitelo e o crescimento dos embriões. As cheias e os alagamentos são importantes fatores de perda de ninhos nas espécies de tartaruga de água doce. A desova no momento adequado possibilita uma incubação segura, sem a interferência de alagamentos dos ninhos e conseqüente morte dos embriões. A predação dos ninhos varia de acordo com o local da desova, o tipo e a abundância de predadores e a profundidade da câmara de ovos. A escolha de pontos de desova no interior da vegetação, onde a taxa de predação é geralmente menor, nem sempre é a estratégia mais frequentemente adotada pelas tartarugas, uma vez que esse procedimento pode levar a uma maior exposição das fêmeas aos predadores, à diminuição do sucesso da eclosão ou a alterações na razão sexual provocadas por diferenças na temperatura da incubação.PalavRas-chave: quelônios, nidificação, embriogênese, predação, eclosão. Environmental factors effects in turtles reproduction AbstrActTurtle species in which the sex determination is dependent of incubation temperature, the nest site and the laying moment will affect more than embryo sex determination. The influence of the laying site extends all over the embryonic development, affecting hatching weight and size. The time of the egg-laying will bring consequences to the nest thermal environment, as the temperature and humidity change throughout the year. The humidity will be decisive in gaseous and hydric exchanges between eggs and the environment, affecting yolk absorption and embryo growth. Floods and inundation are important factors related to nest loss in freshwater turtle species. Egg laying at the appropriated time makes a safe incubation possible, without the interference of nest inundation and subsequent embryo death. The nest predation varies according to the egg-laying site, type and abundance of predator and nest depth. The choice of areas in the middle of vegetation, where the predation rate is generally smaller, is not always the most used strategy by turtles, since this procedure can decrease the hatching success or provoke changes in sex ratio.

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Embryonic temperature determines adult sexuality in a reptile

Cited by 140 publications

References 11 publications

The Adaptive Significance of Temperature-Dependent Sex Determination: Experimental Tests With a Short-Lived Lizard

The Adaptive Significance of Temperature-Dependent Sex Determination: Experimental Tests With a Short-Lived Lizard

Climate and predation dominate juvenile and adult recruitment in a turtle with temperature‐dependent sex determination

Efeitos de Fatores Ambientais na Reprodução de Tartarugas

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