Influence of Moisture, Temperature, and Substrate on Snapping Turtle Eggs and Embryos

Packard, Gary C.; Packard, Mary J.; Miller, Kirk; Boardman, Thomas J.

doi:10.2307/1938369

Cited by 228 publications

(164 citation statements)

References 34 publications

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“…Throughout excavation and transport, we carefully avoided rotating or jostling the eggs. On arrival in the laboratory, we immediately placed the eggs into sealed 0.5-L mason jars with flat sides (Ball, model 1440061180) one-third filled with moist vermiculite (2150 kPa; Packard et al 1987). We buried the eggs two-thirds into the vermiculite and incubated them at a constant 277C (Packard et al 1987).…”

Section: Assessing Thermal Gradients Within Eggsmentioning

confidence: 99%

Reptile Embryos Lack the Opportunity to Thermoregulate by Moving within the Egg

Telemeco

Gangloff

Cordero

et al. 2016

The American Naturalist

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Historically, egg-bound reptile embryos were thought to passively thermoconform to the nest environment. However, recent observations of thermal taxis by embryos of multiple reptile species have led to the widely discussed hypothesis that embryos behaviorally thermoregulate. Because temperature affects development, such thermoregulation could allow embryos to control their fate far more than historically assumed. We assessed the opportunity for embryos to behaviorally thermoregulate in nature by examining thermal gradients within natural nests and eggs of the common snapping turtle (Chelydra serpentina; which displays embryonic thermal taxis) and by simulating thermal gradients within nests across a range of nest depths, egg sizes, and soil types. We observed little spatial thermal variation within nests, and thermal gradients were poorly transferred to eggs. Furthermore, thermal gradients sufficiently large and constant for behavioral thermoregulation were not predicted to occur in our simulations. Gradients of biologically relevant magnitude have limited global occurrence and reverse direction twice daily when they do exist, which is substantially faster than embryos can shift position within the egg. Our results imply that reptile embryos will rarely, if ever, have the opportunity to behaviorally thermoregulate by moving within the egg. We suggest that embryonic thermal taxis instead represents a play behavior, which may be adaptive or selectively neutral, and results from the mechanisms for behavioral thermoregulation in free-living stages coming online prior to hatching. KeywordsChelydra serpentina, microclim, nest, play, soil, snapping turtle, temperature Disciplines Ecology and Evolutionary Biology | Evolution | Population Biology CommentsThis article is from The American Naturalist 188 (2016) abstract: Historically, egg-bound reptile embryos were thought to passively thermoconform to the nest environment. However, recent observations of thermal taxis by embryos of multiple reptile species have led to the widely discussed hypothesis that embryos behaviorally thermoregulate. Because temperature affects development, such thermoregulation could allow embryos to control their fate far more than historically assumed. We assessed the opportunity for embryos to behaviorally thermoregulate in nature by examining thermal gradients within natural nests and eggs of the common snapping turtle (Chelydra serpentina; which displays embryonic thermal taxis) and by simulating thermal gradients within nests across a range of nest depths, egg sizes, and soil types. We observed little spatial thermal variation within nests, and thermal gradients were poorly transferred to eggs. Furthermore, thermal gradients sufficiently large and constant for behavioral thermoregulation were not predicted to occur in our simulations. Gradients of biologically relevant magnitude have limited global occurrence and reverse direction twice daily when they do exist, which is substantially faster than embryos can shift position within the...

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Section: Assessing Thermal Gradients Within Eggsmentioning

confidence: 99%

Reptile Embryos Lack the Opportunity to Thermoregulate by Moving within the Egg

Telemeco

Gangloff

Cordero

et al. 2016

The American Naturalist

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“…In addition to genetic variation and possible maternal effects, environmental factors, such as sand albedo (Hays et al 2001), shading and sun exposure (Standora & Spotila 1985), and moisture from rainfall (Godfrey et al 1996, Houghton et al 2007) may modify nest sex ratios. A number of studies suggest that the hydric environment, in combination with the thermal environment, influences embryonic development and phenotype, including sex in turtles (e.g., Packard et al 1987, Cagle et al 1993, Finkler 2006, LeBlanc & Wibbels 2009, Wyneken & Lolavar 2015. Moisture as rainfall may impact the nest environment, affecting hatchling size (McGehee 1990) and influencing hatchling sex (re viewed by Carthy et al 2003, Wibbels 2003.…”

Section: Introductionmentioning

confidence: 99%

Effect of rainfall on loggerhead turtle nest temperatures, sand temperatures and hatchling sex

Lolavar¹,

Wyneken²

2015

Endang. Species. Res.

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Marine turtles deposit their eggs in underground nests where they develop unattended and without parental care. Incubation temperature varies with environmental conditions, including rainfall, sun/shade and sand type, and affects developmental rates, hatch and emergence success, and embryonic sex. We documented (1) rainfall and sand temperature relationships and (2) rainfall, nest temperatures and hatchling sex ratios at a loggerhead turtle (Caretta caretta) nesting beach in Boca Raton, Florida, USA, across the 2010 to 2013 nesting seasons. Rainfall data collected concurrently with sand temperatures at different depths showed that light rainfall affected surface sand; effects of the heaviest rainfall events tended to lower sand temperatures but the temperature fluctuations were small once upper nest depths were reached. This is important in understanding the potential impacts of rainfall as a modifier of nest temperatures, as such changes can be quite small. Nest temperature profiles were synchronized with rainfall data from weather services to identify relationships with hatchling sex ratios. The sex of each turtle was verified laparoscopically to provide empirical measures of sex ratio for the nest and nesting beach. The majority of hatchlings in the samples were female, suggesting that across the 4 seasons most nest temperatures were not sufficiently cool to produce males. However, in the early portion of the nesting season and in wet years, nest temperatures were cooler, and significantly more males hatched.

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“…alguns experimentos realizados em laboratório apontam que fatores como temperatura, umidade, potencial hídrico, e tensões gasosas dentro do ninho, podem implicar na mortalidade e surgimento de anomalias nos embriões de répteis (lynn & ullrich, 1950;Packard et al 1987;Packard & Packard, 1988). o ambiente hídrico e termal dos ninhos dos quelônios pode ser influenciado por vários fatores ambientais e ecológicos, dentre eles a profundidade do ninho (Burger, 1976;Wilhoft et al, 1983), posicionamento do ninho e cobertura vegetal (vogt & Bull, 1984) e data da desova (Mrosovsky et al, 1984).…”

Section: Discussionunclassified

Avaliação de padrão irregular dos escudos do casco em Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae)

2009

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RESUMOo casco de Podocnemis expansa (tartaruga-da-amazônia) e Podocnemis unifilis (tracajá), os maiores quelônios de água doce da américa do Sul, é uma estrutura única que diferencia esse grupo dos vertebrados atuais e está associado a alguns padrões comportamentais. o padrão dos escudos que compõem o casco dos quelônios é bastante uniforme, mas variações já foram descritas e analisadas para um grande número de espécies em todas as famílias existentes atualmente. averiguou-se a incidência de irregularidades do padrão de escutelação no casco dessas espécies, durante os anos de 1999 a 2003 no rio Javaés, entorno do Parque nacional do araguaia e da Área de Proteção ambiental Bananal/ Cantão, oeste do estado do Tocantins. P. expansa se apresenta como uma espécie mais suscetível à ocorrência de anormalidades no casco em relação a P. unifilis. Sendo que, dos 14.378 filhotes avaliados, (13,32 %) apresentavam irregularidades no padrão de escutelação enquanto que dos 1.329 filhotes de P. unifilis apenas (4,44 %). em P. expansa, os defeitos ocorreram quase que em sua totalidade na carapaça (98,64 %) e em menor número (83,05 %) em P. unifilis. PALAVRAS-CHAVE:Podocnemis expansa, Podocnemis unifilis, anormalidade, casco, rio Javaés. Evaluation of irregular pattern of the shell scutes in Podocnemis expansa and Podocnemis unifilis (Testudines, Podocnemididae) ABSTRACTThe shell of Podocnemis expansa (amazonian giant river turtle) and Podocnemis unifilis (Yellow-spotted amazon river Turtle), the largest South american turtles, is a unique structure that differentiates them from other known vertebrates; and it is associated with some of their behavioral patterns. Their scute pattern is quite uniform however variations have been described and analyzed for a great number of other species of existing families. in the Javaés river, from 1999 to 2003, we observed an occurrence of abnormalities in their scute pattern. This was in the vicinity of the araguaia national Park and the Bananal/ Cantão environment Protected area, west of Tocantins state. of the both species, P. expansa is more susceptible to shell abnormalities. of 14.378 P. expansa hatchlings observed, 13.32 % presented scute pattern abnormalities, while of 1.329 P. unifilis hatchlings, only 4.44 %. The incidence of abnormalities occurred only in the carapace, namely, 98.64% in P. expansa, and 83.05% in P. unifilis.

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Influence of Moisture, Temperature, and Substrate on Snapping Turtle Eggs and Embryos

Cited by 228 publications

References 34 publications

Reptile Embryos Lack the Opportunity to Thermoregulate by Moving within the Egg

Reptile Embryos Lack the Opportunity to Thermoregulate by Moving within the Egg

Effect of rainfall on loggerhead turtle nest temperatures, sand temperatures and hatchling sex

Avaliação de padrão irregular dos escudos do casco em Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae)

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