Embryonic aestivation and emergence behaviour in the pig-nosed turtle, &lt;i&gt;Carettochelys insculpta&lt;/i&gt;

Doody, J. Sean; Georges, Arthur; Young, Jeanne E.; Pauza, Matthew; Pepper, Ashe L.; Alderman, Rachael; Welsh, Michael A.

doi:10.1139/cjz-79-6-1062

Cited by 16 publications

(6 citation statements)

References 27 publications

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“…In the pignose turtle (Carettochelys insculpta), full-term embryos go into diapause until they experience a rapid fall in oxygen availability. This happens when the first floods of the wet season inundate the nesting beaches, thus stimulating explosive hatching of the young turtles coincident with flooding, when survival chances of hatchling turtles may be maximized (Doody et al 2001).…”

Section: Adaptations Of Embryonic Biologymentioning

confidence: 99%

Adapting to the unpredictable: reproductive biology of vertebrates in the Australian wet–dry tropics

Shine

Brown

2007

Phil. Trans. R. Soc. B

145

126

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In the wet-dry tropics of northern Australia, temperatures are high and stable year-round but monsoonal rainfall is highly seasonal and variable both annually and spatially. Many features of reproduction in vertebrates of this region may be adaptations to dealing with this unpredictable variation in precipitation, notably by (i) using direct proximate (rainfall-affected) cues to synchronize the timing and extent of breeding with rainfall events, (ii) placing the eggs or offspring in conditions where they will be buffered from rainfall extremes, and (iii) evolving developmental plasticity, such that the timing and trajectory of embryonic differentiation flexibly respond to local conditions. For example, organisms as diverse as snakes (Liasis fuscus, Acrochordus arafurae), crocodiles (Crocodylus porosus), birds (Anseranas semipalmata) and wallabies (Macropus agilis) show extreme annual variation in reproductive rates, linked to stochastic variation in wet season rainfall. The seasonal timing of initiation and cessation of breeding in snakes (Tropidonophis mairii ) and rats (Rattus colletti ) also varies among years, depending upon precipitation. An alternative adaptive route is to buffer the effects of rainfall variability on offspring by parental care (including viviparity) or by judicious selection of nest sites in oviparous taxa without parental care. A third type of adaptive response involves flexible embryonic responses (including embryonic diapause, facultative hatching and temperature-dependent sex determination) to incubation conditions, as seen in squamates, crocodilians and turtles. Such flexibility fine-tunes developmental rates and trajectories to conditions--especially, rainfall patterns--that are not predictable at the time of oviposition.

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Section: Adaptations Of Embryonic Biologymentioning

confidence: 99%

Adapting to the unpredictable: reproductive biology of vertebrates in the Australian wet–dry tropics

Shine

Brown

2007

Phil. Trans. R. Soc. B

145

126

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“…Freshwater turtle hatchlings experience much higher natural mortality rates compared to older age classes (Iverson, 1991;Wilbur, 1975). Survival rates of hatchlings following emergence from the nest are affected by several factors that vary temporally, including the availability of food resources (Gibbons & Nelson, 1978), the abundance of predators (Janzen et al, 2000;Paterson et al, 2012Paterson et al, , 2014, dispersal opportunities (Doody et al, 2001;Nagle et al, 2004) and the thermal environment (Moran et al, 1999). Because of this, intraspecific and interspecific variations in the timing of hatchling emergence are common (Gibbons & Nelson, 1978;, and there are three broad strategies:…”

Section: Emergence Timing Strategies and Triggersmentioning

confidence: 99%

“…Temperature and rainfall are key environmental parameters that are known to influence hatchling emergence in other freshwater turtle species (DePari, 1996;Doody et al, 2001;Gibbons & Nelson, 1978;Moll & Legler, 1971;Moran et al, 1999;Nagle et al, 2004;Santidrián Tomillo et al, 2015;Tucker, 1999). These data were sourced from the Australian…”

Section: Environmental Parametersmentioning

confidence: 99%

“…Hatching synchrony was not exhibited by C. oblonga. While hatching synchrony has been observed in several species of freshwater turtles (Burger, 1976;Doody et al, 2001;Lacroix et al, 2022;McGlashan et al, 2012;Spencer et al, 2001), reports of asynchronous hatching were found in only one other species (Riley et al, 2020). Synchronous hatching is suggested to facilitate synchronous emergence from the nest (Spencer et al, 2001;Tucker et al, 2008) and likely occurs when an environmental cue signals favourable conditions for hatching and emergence (Doody, 2011;Doody et al, 2012).…”

Section: Hatching Strategymentioning

confidence: 99%

“…The emergence of C. oblonga hatchlings was enhanced by rainfall (in the week of emergence) during the autumn period, though this was not quite a significant relationship. Similarly, the autumn emergence of other Australian freshwater turtles' hatchlings (P. umbrina and Carettochelys insculpta) has been found to be triggered by rainfall, with the authors contending that the onset of the wet season increases feeding opportunities (Burbidge, 1981;Doody et al, 2001). A relationship between autumn emergence and rainfall could have negative ramifications for C. oblonga recruitment given the projected continued decline of rainfall in the southwestern Australian region (Hope et al, 2015;Intergovernmental Panel on Climate Change, 2023;Silberstein et al, 2012).…”

Section: Effects Of Rainfallmentioning

confidence: 99%

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Climate change affects the early‐life history of a freshwater turtle in a severely drying region

Santoro,

Chambers,

Ebner

et al. 2023

Austral Ecology

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Freshwater turtles are one of the most threatened vertebrate groups. Climate change is a major threat to these species, with impacts affecting all life‐history stages. There is currently a limited understanding of how changes in climate may alter the environmental triggers for hatching and emergence from the nests of freshwater turtle hatchlings. This precludes making predictions about how climate change may impact freshwater turtle recruitment success. The southwestern snake‐necked turtle (Chelodina oblonga) is endemic to south‐western Australia, a global biodiversity hotspot that has undergone severe climatic drying. Recruitment failure is thought to be occurring in many populations of the species. However, there is little understanding as to how environmental change may be influencing recruitment. This study aimed to: (1) determine the incubation duration and hatching and hatchling emergence success of C. oblonga, (2) determine if the species exhibits hatching or emergence synchrony and/or delayed emergence and (3) quantify the effects of temperature and rainfall on hatchling emergence. Using this information, the study assesses how climatic drying and warming may be impacting C. oblonga's early life‐history. Between 2018 and 2020 nest sites were monitored around a large urban wetland with weekly assessments of egg and hatchling status. Incubation duration and hatching and hatchling emergence success were calculated, and generalized linear models were built to determine how temperature and/or rainfall predicted emergence. Hatchlings either emerged shortly after hatching or overwintered in the nest, and both hatching and emergence were asynchronous. Both emergence periods were positively associated with temperature and rainfall. This study reveals that incubation duration, hatching success, hatchling emergence and survival are all likely to be impacted by recent and projected climate change, and especially drying. Warming and drying are predicted for many temperate regions globally, and it is therefore important that their impacts on the early life history of freshwater turtles be better understood.

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Twice every second year: reproduction in the pig‐nosed turtle, Carettochelys insculpta, in the wet–dry tropics of Australia

2003

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The reproductive biology of female pig-nosed turtles Carettochelys insculpta was studied for 4 years in the wetdry tropics of northern Australia. Females matured at around 6 kg body mass (38.0 cm curved carapace length, 30.5 cm plastron length). Turtles produced egg sizes and clutch sizes similar to that of other turtle species similar in size. Turtles reproduced every second year, but produced two clutches within years, about 41 days apart. Thus, it appeared that females were energy limited, possibly due to the low available energy content of the dry season diet (aquatic vegetation). Life-history theory predicts that some costly behaviour associated with reproduction exists, such that by skipping years turtles could reduce that cost and put the savings into future reproduction. Previous work revealed no behaviour associated with reproduction in the population. Within years, clutch mass did not differ between early (first) and late (second) clutches. However, early clutches tended to have more eggs per clutch but smaller eggs than late clutches, a new finding for turtles that has been demonstrated in lizards and other animals. Because the study spanned both years with 'big' and 'small' wet seasons, we were able to examine how the magnitude of the wet season influenced reproductive characteristics. Following big wet seasons, turtles produced larger, heavier, and more eggs per clutch than they did after small wet seasons. Relationships among body size, egg size and clutch size were evident after two big wet seasons but not apparent after two small wet seasons. Collectively, annual variation in reproductive characteristics and current life-history theory suggest that a big wet season is a time of high energy accumulation for the turtles.

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Embryonic aestivation and emergence behaviour in the pig-nosed turtle, <i>Carettochelys insculpta</i>

Cited by 16 publications

References 27 publications

Adapting to the unpredictable: reproductive biology of vertebrates in the Australian wet–dry tropics

Adapting to the unpredictable: reproductive biology of vertebrates in the Australian wet–dry tropics

Climate change affects the early‐life history of a freshwater turtle in a severely drying region

Twice every second year: reproduction in the pig‐nosed turtle, Carettochelys insculpta, in the wet–dry tropics of Australia

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