The Evolutionary Significance of Delayed Emergence from the Nest by Hatchling Turtles

Gibbons, J. Whitfield; Nelson, David H.

doi:10.2307/2407597

Cited by 72 publications

(51 citation statements)

References 16 publications

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“…Incubation temperature has little effect on body size at hatching in tuatara (Nelson et al 2004b), but the energetic consequences of early maturity will depend on whether hatchlings immediately emerge from the nest or overwinter in the nest cavity. Evidence from a review of emergence patterns in turtles that nest in spring and reach hatchling stage in autumn suggests that the phenomenon of overwintering in the nest may be adaptive in ensuring that hatchlings emerge in favourable spring conditions (Gibbons & Nelson 1978). If maximum warming promotes autumn maturity for tuatara, as our models suggest, then any hatchlings that overwinter will do so under much warmer nest temperatures than they do now, as the 48C rise in winter air temperatures is predicted to be the most dramatic.…”

Section: Resultsmentioning

confidence: 99%

Predicting the fate of a living fossil: how will global warming affect sex determination and hatching phenology in tuatara?

et al. 2008

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How will climate change affect species' reproduction and subsequent survival? In many egg-laying reptiles, the sex of offspring is determined by the temperature experienced during a critical period of embryonic development (temperature-dependent sex determination, TSD). Increasing air temperatures are likely to skew offspring sex ratios in the absence of evolutionary or plastic adaptation, hence we urgently require means for predicting the future distributions of species with TSD. Here we develop a mechanistic model that demonstrates how climate, soil and topography interact with physiology and nesting behaviour to determine sex ratios of tuatara, cold-climate reptiles from New Zealand with an unusual developmental biology. Under extreme regional climate change, all-male clutches would hatch at 100% of current nest sites of the rarest species, Sphenodon guntheri, by the mid-2080s. We show that tuatara could behaviourally compensate for the male-biasing effects of warmer air temperatures by nesting later in the season or selecting shaded nest sites. Later nesting is, however, an unlikely response to global warming, as many oviparous species are nesting earlier as the climate warms. Our approach allows the assessment of the thermal suitability of current reserves and future translocation sites for tuatara, and can be readily modified to predict climatic impacts on any species with TSD.

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Section: Resultsmentioning

confidence: 99%

Predicting the fate of a living fossil: how will global warming affect sex determination and hatching phenology in tuatara?

et al. 2008

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“…Terrestrial overwintering of hatchlings is typical of many, if not most, North American turtles with TSD and is apparently absent in all five North American turtles with GSD (i.e. Apalone and Glyptemys) [18,19,22]. Natural nests of painted turtles were studied on an island (the Thomson Causeway) in the Mississippi River near Thomson, Carroll County, IL, USA (41857 0 N, 9087 0 W).…”

Section: Materials and Methods (A) Study Species And Populationmentioning

confidence: 99%

“…The steadfast focus on incubation conditions may be misplaced at least in the many turtle species in which hatchlings overwinter in the natal nest or in other terrestrial circumstances [18,19]. Here, this distinct life stage offers an opportunity for TSD to enhance maternal/hatchling fitness beyond incubation conditions.…”

Section: Introductionmentioning

confidence: 99%

“…We test this novel hypothesis using the painted turtle (Chrysemys picta), a species with TSD in which eggs hatch in late summer and hatchlings remain within natal nests until the following spring. This overwintering trait is quite common in turtles with TSD, particularly those with geographical ranges in temperate zones [18,19]. To survive for these many months of terrestrial aestivation, hatchlings rely on maternally provisioned yolk reserves and other sources of stored energy, whose depletion depends on post-hatching thermal conditions [20,21], which may differ between male-producing (generally cooler) and female-producing (generally warmer) nests [22].…”

Section: Introductionmentioning

confidence: 99%

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A novel hypothesis for the adaptive maintenance of environmental sex determination in a turtle

Spencer

Janzen

2014

Proc. R. Soc. B.

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Temperature-dependent sex determination (TSD) is widespread in reptiles, yet its adaptive significance and mechanisms for its maintenance remain obscure and controversial. Comparative analyses identify an ancient origin of TSD in turtles, crocodiles and tuatara, suggesting that this trait should be advantageous in order to persist. Based on this assumption, researchers primarily, and with minimal success, have employed a model to examine sex-specific variation in hatchling phenotypes and fitness generated by different incubation conditions. The unwavering focus on different incubation conditions may be misplaced at least in the many turtle species in which hatchlings overwinter in the natal nest. If overwintering temperatures differentially affect fitness of male and female hatchlings, TSD might be maintained adaptively by enabling embryos to develop as the sex best suited to those overwintering conditions. We test this novel hypothesis using the painted turtle (Chrysemys picta), a species with TSD in which eggs hatch in late summer and hatchlings remain within nests until the following spring. We used a split-clutch design to expose field-incubated hatchlings to warm and cool overwintering (autumn -winter-spring) regimes in the laboratory and measured metabolic rates, energy use, body size and mortality of male and female hatchlings. While overall mortality rates were low, males exposed to warmer overwintering regimes had significantly higher metabolic rates and used more residual yolk than females, whereas the reverse occurred in the cool temperature regime. Hatchlings from mixed-sex nests exhibited similar sex-specific trends and, crucially, they were less energy efficient and grew less than same-sex hatchlings that originated from single-sex clutches. Such sex-and incubation-specific physiological adaptation to winter temperatures may enhance fitness and even extend the northern range of many species that overwinter terrestrially.

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“…Survival of overwintering turtle hatchlings in a nest frequented by fire ants is unlikely. Delayed emergence decreases hatchling mortality by providing a sanctuary from predators and harsh environmental conditions (Gibbons and Nelson, 1978). Fire ants may negate the value of the nest cavity as a sanctuary by establishing foraging tunnels into the cavity following egg laying.…”

Section: Impacts On Reptiles and Amphibiansmentioning

confidence: 99%

Red Imported Fire Ant Impacts on Wildlife: A Decade of Research

Allen

Epperson

Garmestani³

2004

The American Midland Naturalist

206

168

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The Evolutionary Significance of Delayed Emergence from the Nest by Hatchling Turtles

Cited by 72 publications

References 16 publications

Predicting the fate of a living fossil: how will global warming affect sex determination and hatching phenology in tuatara?

Predicting the fate of a living fossil: how will global warming affect sex determination and hatching phenology in tuatara?

A novel hypothesis for the adaptive maintenance of environmental sex determination in a turtle

Red Imported Fire Ant Impacts on Wildlife: A Decade of Research

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