Communal nesting under climate change: fitness consequences of higher incubation temperatures for a nocturnal lizard

Communal nesting lizards may be vulnerable to climate warming, particularly if air temperatures regulate nest temperatures. In southeastern Australia, velvet geckos Oedura lesueurii lay eggs communally inside rock crevices. We investigated whether increases in air temperatures could elevate nest temperatures, and if so, how this could influence hatching phenotypes, survival, and population dynamics. In natural nests, maximum daily air temperature influenced mean and maximum daily nest temperatures, implying that nest temperatures will increase under climate warming. To determine whether hotter nests influence hatchling phenotypes, we incubated eggs under two fluctuating temperature regimes to mimic current ‘cold’ nests (mean = 23.2 °C, range 10–33 °C) and future ‘hot’ nests (27.0 °C, 14–37 °C). ‘Hot’ incubation temperatures produced smaller hatchlings than did cold temperature incubation. We released individually marked hatchlings into the wild in 2014 and 2015, and monitored their survival over 10 months. In 2014 and 2015, hot‐incubated hatchlings had higher annual mortality (99%, 97%) than cold‐incubated (11%, 58%) or wild‐born hatchlings (78%, 22%). To determine future trajectories of velvet gecko populations under climate warming, we ran population viability analyses in Vortex and varied annual rates of hatchling mortality within the range 78– 96%. Hatchling mortality strongly influenced the probability of extinction and the mean time to extinction. When hatchling mortality was >86%, populations had a higher probability of extinction (PE: range 0.52– 1.0) with mean times to extinction of 18–44 years. Whether future changes in hatchling survival translate into reduced population viability will depend on the ability of females to modify their nest‐site choices. Over the period 1992–2015, females used the same communal nests annually, suggesting that there may be little plasticity in maternal nest‐site selection. The impacts of climate change may therefore be especially severe on communal nesting species, particularly if such species occupy thermally challenging environments.     

Incubation temperature and phenotypic traits of Sceloporus undulatus: implications for the northern limits of distribution

Cold environmental temperature is detrimental to reproduction by oviparous squamate reptiles by prolonging incubation period, negatively affecting embryonic developmental processes, and by killing embryos in eggs directly. Because low soil temperature may prevent successful development of embryos in eggs in nests, the geographic distributions of oviparous species may be influenced by the thermal requirements of embryos. In the present study, we tested the hypothesis that low incubation temperature determines the northern distributional limit of the oviparous lizard Sceloporus undulatus. To compare the effects of incubation temperature on incubation length, egg and hatchling survival, and hatchling phenotypic traits, we incubated eggs of S. undulatus under temperature treatments that simulated the thermal environment that eggs would experience if located in nests within their geographic range at 37°N and north of the species’ present geographic range at latitudes of 44 and 42°N. After hatching, snout–vent length (SVL), mass, tail length, body condition (SVL relative to mass), locomotor performance, and growth rate were measured for each hatchling. Hatchlings were released at a field site to evaluate growth and survival under natural conditions. Incubation at temperatures simulating those of nests at 44°N prolonged incubation and resulted in hatchlings with shorter SVL relative to mass, shorter tails, shorter hind limb span, slower growth, and lower survival than hatchlings from eggs incubated at temperatures simulating those of nests at 37 and 42°N. We also evaluated the association between environmental temperature and the northern distribution of S. undulatus. We predicted that the northernmost distributional limit of S. undulatus would be associated with locations that provide the minimum heat sum (∼495 degree-days) required to complete embryonic development. Based on air and soil temperatures, the predicted northern latitudinal limit of S. undulatus would lie at ∼40.5–41.5°N. Our predicted value closely corresponds to the observed latitudinal limit in the eastern United States of ∼40°N. Our results suggest that soil temperatures at northern latitudes are not warm enough for a sufficient length of time to permit successful incubation of S. undulatus embryos. These results are consistent with the hypothesis that incubation temperature is an important factor limiting the geographic distributions of oviparous reptile species at high latitudes and elevations.     

Influence of water availability during incubation on hatchling size, body composition, desiccation tolerance, and terrestrial locomotor performance in the snapping turtle Chelydra serpentina

The effects of water availability during incubation on the water contents of neonatal snapping turtles at hatching were examined, along with the influence of hatchling water content on desiccation tolerance and terrestrial locomotor performance. The water contents of hatchlings from eggs incubated on wet substrates were both absolutely and proportionally greater than were those of hatchlings from eggs incubated on dry substrates. Hatchlings with greater water contents at hatching were able to survive longer and to lose more water before physiological performance was adversely affected by desiccation. Increased water contents in hatchlings with greater water availability during incubation may enhance survival by increasing the amount of water the animal can afford to lose before dehydration begins to adversely affect whole animal performance.     

Phenotypic responses of hatchlings to constant versus fluctuating incubation temperatures in the multi-banded krait, Bungarus multicintus (Elapidae)

Most studies on egg incubation in reptiles have relied on constant temperature incubation in the laboratory rather than on simulations of thermal regimes in natural nests. The thermal effects on embryos in constant-temperature studies often do not realistically reflect what occurs in nature. Recent studies have increasingly recognized the importance of simulating natural nest temperatures rather than applying constant-temperature regimes. We incubated Bungarus multicintus eggs under three constant and one fluctuating-temperature regimes to evaluate the effects of constant versus fluctuating incubation temperatures on hatching success and hatchling phenotypes. Hatching success did not differ among the four treatments, and incubation temperature did not affect the sexual phenotype of hatchlings. Incubation length decreased as incubation temperature increased, but eggs incubated at fluctuating temperatures did not differ from eggs incubated at constant temperatures with approximately the same mean in incubation length. Of the hatchling phenotypes examined, residual yolk, fat bodies and locomotor performance were more likely affected by incubation temperature. The maximal locomotor speed was fastest in the fluctuating-temperature and 30 degrees C treatments and slowest in the 24 degrees C treatment, with the 27 degrees C treatment in between. The maximal locomotor length was longest in the fluctuating-temperature treatment and shortest in the 24 degrees C and 27 degrees C treatments, with the 30 degrees C treatment in between. Our results show that fluctuating incubation temperatures do not influence hatching success and hatchling size and morphology any differently than constant temperatures with approximately the same mean, but have a positive effect on locomotor performance of hatchlings.     

Effects of incubation temperature on the energetics of embryonic development and hatchling morphology in the Brisbane river turtle Emydura signata

Incubation temperature and the amount of water taken up by eggs from the substrate during incubation affects hatchling size and morphology in many oviparous reptiles. The Brisbane river turtle Emydura signata lays hard-shelled eggs and hatchling mass was unaffected by the amount of water gained or lost during incubation. Constant temperature incubation of eggs at 24 °C, 26 °C, 28 °C and 31 °C had no effect on hatchling mass, yolk-free hatchling mass, residual yolk mass, carapace length, carapace width, plastron length or plastron width. However, hatchlings incubated at 26 °C and 28 °C had wider heads than hatchlings incubated at 24 °C and 31 °C. Incubation period varied inversely with incubation temperature, while the rate of increase in oxygen consumption during the first part of incubation and the peak rate of oxygen consumption varied directly with incubation temperature. The total amount of oxygen consumed during development and hatchling production cost was significantly greater at 24 °C than at 26 °C, 28 °C and 31 °C. Hatchling mass and dimensions and total embryonic energy expenditure was directly proportional to initial egg mass. Accepted: 18 March 1998     

孵化温度对赤链蛇胚胎代谢和幼体行为的影响

研究了赤链蛇(Dinodon rufozonatum)在孵化过程中卵的生长、孵化期、胚胎代谢和孵出幼体行为表现的热依赖性。结果显示:孵化温度对孵化期、卵增重、孵化过程中消耗的总能量和孵出幼体的运动表现有显著影响,但不影响胚胎代谢率、孵化成功率和幼体吐信频次。孵化期随着孵化温度的升高而缩短,孵化过程中,24℃终末卵重和胚胎代谢率显著大于30℃,而27℃与其他两个温度没有差异;27℃孵出幼体游速较24℃快,30℃孵出幼体与其他两个温度孵出幼体的游速无显著差异。上述结果显示:24—30℃是赤链蛇适合的孵化温度范围,与赤链蛇所处的生境温度相近。     

Fluctuations in the incubation moisture environment affect growth but not survival of hatchling lizards

Few studies have collected longitudinal data that follow the complete microevolutionary path of an organism linking sources of variation (e.g. environmental versus genetic) to a trait and its subsequent relationship with fitness. Identifying the links within this pathway is imperative for understanding the ecological relevance of effects found at the phenotypic level. Furthermore, experimental studies that examine parts of the pathway in ectothermic organisms often fail to mimic the complexities of the natural developmental environment. Temperature and moisture conditions in reptile nests, for example, can fluctuate greatly on a seasonal and daily basis. Despite the potential effects of fluctuating environments, the vast majority of studies have held environmental treatments constant during the developmental period. We investigated the effects of fluctuating moisture regimes during incubation on eggs, hatchling phenotypes, and subsequent survival in the eastern fence lizard Sceloporus undulatus. Moisture fluctuations during embryonic development caused water absorption by eggs to follow the environmental availability of moisture. Initial hatchling tail length was affected by the pattern of moisture fluctuations, and hatchling growth rates in fluctuating treatments were significantly faster than those in a constant treatment, resulting in larger hatchlings after 4 weeks. A release–recapture experiment conducted in the field did not detect a treatment effect on survival despite the larger body sizes. In summary, although fluctuations affected water absorption by eggs and some hatchling traits, these effects did not have subsequent fitness consequences. The results obtained suggest that egg and hatchling survival are buffered against natural soil moisture fluctuations during incubation, even when egg and hatchling traits are significantly affected. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 89–102.     

Sex of incubation neighbours influences hatchling sexual phenotypes in an oviparous lizard

In many litter-bearing mammals and in a few viviparous reptiles the sex ratio of the entire brood or the sex of the adjacent fetuses induces sex-specific differences in the hatchling’s phenotype. This study examines whether the sex of incubation neighbours affects hatchling characteristics in oviparous common lizards (Lacerta vivipara). Oviparous common lizards lay eggs with thin eggshells and, therefore, are an optimal model organism for studying the effects of hormone leakage among developing embryos since the strongest evidence for prenatal sex ratio effects on offspring development comes from viviparous populations of the same species. Groups of three eggs were incubated together and were categorised according to the sex of the resulting hatchlings as either homosex (three hatchlings of the same sex) or heterosex (one male or one female hatchling plus two siblings of the opposite sex). Hatchlings incubated adjacent to siblings of the same sex had larger body mass and body condition. Males tended to have lower ventral scale counts when incubated with other males. Conversely, females tended to have more ventral scales when incubated with other females, indicative of a more feminised phenotype. There was also a significant interaction between hatchling sex and incubation environment with respect to the length of the fourth digit of the hindlimb, likely indicative of masculinisation in heterosex females. This study suggests steroid diffusion between adjacent eggs in a minimally manipulative experiment and provides the first evidence for developmental effects of the exogenous hormonal environment in near natural conditions in an oviparous amniote. Implications of these results for the evolution of within-clutch sex ratio are discussed.     

The variance of incubation temperatures does not affect the phenotype of hatchlings in a colubrid snake, Xenochrophis piscator

It has been documented in some reptiles that fluctuating incubation temperatures influence hatchling traits differently than constant temperatures even when the means are the same between treatments; yet whether the observed effects result from the thermal variance, temperature extremes or both is largely unknown. We incubated eggs of the checkered keelback snake Xenochrophis piscator under one fluctuating (Ft) and three constant (24, 27 and 30 °C) temperatures to examine whether the variance of incubation temperatures plays an important role in influencing the phenotype of hatchlings. The thermal conditions under which eggs were incubated affected a number of hatchling traits (wet mass, SVL, tail length, carcass dry mass, fatbody dry mass and residual yolk dry mass) but not hatching success and the sex ratio of hatchlings. Body sizes were larger in hatchlings from incubation temperatures of 24 and 27 °C compared with the other two treatments. Hatchlings from the four treatments could be divided into two groups: one included hatchlings from the 24 and 27 °C treatments, and the other included hatchlings from the 30 °C and Ft treatments. In the Ft treatment, the thermal variance was not a significant predictor of all examined hatchling traits, and incubation length was not correlated with the thermal variance when holding the thermal mean constant. The results of this study show that the mean rather than the variance of incubation temperatures affects the phenotype of hatchlings.     

Gold climates and the evolution of viviparity in reptiles: cold incubation temperatures produce poor-quality offspring in the lizard, Sceloporus virgatus

Evolutionary origins of viviparity among the squamate reptiles are strongly associated with cold climates, and cold environmental temperatures are thought to be an important selective force behind the transition from egg-laying to live-bearing. In particular, the low nest temperatures associated with cold climate habitats are thought to be detrimental to the developing embryos or hatchlings of oviparous squamates, providing a selective advantage for the retention of developing eggs in utero, where the mother can provide warmer incubation temperatures for her eggs (by actively thermoregulating) than they would experience in a nest. However, it is not entirely clear what detrimental effects cold incubation temperatures may have on eggs and hatchlings, and what role these effects may play in favouring the evolution of viviparity. Previous workers have suggested that viviparity may be favoured in cold climates because cold incubation temperatures slow cmbryogenesis and delay hatching of the eggs, or because cold nest temperatures are lethal to developing eggs and reduce hatching success. However, incubation temperature has also been shown to have other, potentially long-term, effects on hatchling phcnotypcs, suggesting that cold climates may favour viviparity because cold incubation temperatures produce offspring of poor quality or low fitness. We experimentally incubated eggs of the oviparous phrynosomatid lizard, Sceloporus virgatus, at temperatures simulating nests in a warm (low elevation) habitat, as is typical for this species, and nests in a colder (high elevation) habitat, to determine the effects of cold incubation temperatures on embryonic development and hatchling phenotypes. Incubation at cold nest temperatures slowed embryonic development and reduced hatching success, but also affected many aspects of the hatchlings' phenotypes. Overall, the directions of these plastic responses indicated that cold-incubated hatchlings did indeed exhibit poorer quality phenotypes; they were smaller at hatching (in body length) and at 20 days of age (in length and mass), grew more slowly (in length and mass), had lower survival rates, and showed greater fluctuating asymmetry than their conspecifics that were incubated at warmer temperatures. Our findings suggest that cold nest temperatures are detrimental to S. virgatus, by delaying hatching of their eggs, reducing their hatching success, and by producing poorer quality offspring. These negative effects would likely provide a selective advantage for any mechanism through which these lizards could maintain warmer incubation temperatures in cold climates, including the evolution of prolonged egg retention and viviparity.     

Influence of the nest environment on bone mineral content in hatchling painted turtles (Chrysemys picta)

We performed an experiment at a field site in north-central Nebraska to assess the role of the nest environment in inducing variation in bone mineral content in hatchling painted turtles Chrysemys picta (Schneider 1783). The contents of several newly constructed nests were manipulated by reciprocal transplant, after which the eggs were allowed to incubate for 8 wk under natural conditions. The nests were then excavated, and the eggs were brought into the laboratory to complete incubation and hatch under standard conditions of temperature and moisture. The hatchlings were killed, and their carcasses and residual yolks were analyzed separately for calcium and phosphorus. More of the random variation in carcass calcium and phosphorus was related to the nest in which eggs incubated (37% and 42%, respectively) than was associated with the clutch of origin (21% and 37%). Moreover, hatchlings from some nests contained substantially more calcium and phosphorus than did hatchlings from other nests, both in terms of the absolute amounts of the elements in their carcasses (pointing to variation in body size) and in terms of the concentrations of those elements (pointing to variation in bone density). The amounts of calcium and phosphorus in carcasses of hatchlings were positively correlated with changes in mass of their eggs during the 8 wk that the eggs incubated in nests in the field, thereby indicating that the influence of the nest environment on developing embryos probably was mediated by water exchanges experienced by the eggs. These findings indicate that developmental plasticity underlies a major fraction of the variation in mineral content of hatchling painted turtles emerging from nests in the field. Phenotypic variation attributable to plasticity consequently needs to be addressed in models for life-history evolution of painted turtles and other chelonians producing eggs with soft, flexible shells.     

Comparisons of egg incubation and hatchling traits among captive cohorts of the Chinese three-keeled pond turtle, Chinemys reevesii

Freshly-laid eggs of the Chinese three-keeled pond turtle (Chinemys reevesii) from captive cohorts in Hunan, Shanghai and Jiangxi were incubated at four constant temperatures of 24, 26, 28 and 30 °C to assess the effects of incubation temperature and cohort origin on incubation duration and hatchling phenotypes. Eggs from the three cohorts differed in size and shape. Egg mass and width were greatest in the Hunan cohort, smallest in the Jiangxi cohort, with the Shanghai cohort in between. Incubation duration decreased with increasing temperature and differed among the cohorts, with longer incubation duration for eggs from the Jiangxi cohort than those from the Hunan or Shanghai cohorts. Incubation temperatures significantly affected hatchling size and hatchlings from 30 °C were smaller than those from the lower temperatures in terms of carapace size and body mass. When incubated at a common temperature, hatchlings from the Hunan and Shanghai cohorts were larger than those from the Jiangxi cohort. The swimming capacity of hatchlings was affected by incubation temperature, but did not differ among the cohorts. The characteristics of eggs and hatchlings were similar among the Hunan and Shanghai cohorts, but they differed significantly from the Jiangxi cohort.     

Comparisons of egg incubation and hatchling traits among captive cohorts of the Chinese three-keeled pond turtle, Chinemys reevesii

Freshly-laid eggs of the Chinese three-keeled pond turtle (Chinemys reevesii) from captive cohorts in Hunan, Shanghai and Jiangxi were incubated at four constant temperatures of 24, 26, 28 and 30 °C to assess the effects of incubation temperature and cohort origin on incubation duration and hatchling phenotypes. Eggs from the three cohorts differed in size and shape. Egg mass and width were greatest in the Hunan cohort, smallest in the Jiangxi cohort, with the Shanghai cohort in between. Incubation duration decreased with increasing temperature and differed among the cohorts, with longer incubation duration for eggs from the Jiangxi cohort than those from the Hunan or Shanghai cohorts. Incubation temperatures significantly affected hatchling size and hatchlings from 30 °C were smaller than those from the lower temperatures in terms of carapace size and body mass. When incubated at a common temperature, hatchlings from the Hunan and Shanghai cohorts were larger than those from the Jiangxi cohort. The swimming capacity of hatchlings was affected by incubation temperature, but did not differ among the cohorts. The characteristics of eggs and hatchlings were similar among the Hunan and Shanghai cohorts, but they differed significantly from the Jiangxi cohort.     

Changes in mass of eggs of softshell turtless (Trionyx spiniferus) incubated under hydric conditions simulating those of natural nests

Rigid-shelled eggs of softshell turtles ( Trionyx spiniferus ) incubated at 29C under hydric conditions simulating those at the interior of natural nests (i.e. eggs not contacting the substrate) declined in mass during incubation owing to the continuous escape of water vapour to air trapped inside the chambers, with eggs incubated in relatively dry chambers declining more in mass than eggs held in relatively wet chambers. Eggs held under hydric conditions approximating those at the periphery of natural nests (i.e. eggs partly buried in the substrate) also declined in mass during incubation, but at lower rates than characterized eggs not contacting the substrate, indicating that absorption of liquid water from the substrate compensated for part of the water vapour escaping to the air inside the chambers. There was no relationship between hatching success and either the position of eggs in the chambers or the wetness of substrates, nor was there any variation among experimental groups in the size of hatchlings. Thus, development of embryos of Trionyx spiniferus seems not to be closely coupled with the hydric environment of the nest, a situation contrasting with that of embryos of those species of turtles producing pliable-shelled eggs.     

恒定和波动温度下丽斑麻蜥孵出幼体的表型变异

作者以丽斑麻蜥(Eremias argus)为模型动物研究恒定和波动孵化温度对孵化成功率和孵出幼体表型的影响。卵在四个恒定[24 ,27 ,30 and 33 (±0·3)℃]、一个波动温度下孵化。不同温度处理下的孵化成功率相同,但孵出幼体表型不同。孵化期随孵化温度升高呈指数式缩短;在相同平均温度下,波动温度孵化卵的孵化期比恒温孵化卵长。在所有被检表型特征中,幼体的干重、剩余卵黄干重和运动表现更易受孵化温度影响。总体而言,低温(24℃、27℃)孵出幼体运动表现最佳,高温(33℃)孵出幼体最差、温和温度(30℃和波动温度)孵出幼体居中。本文研究数据显示: (1)丽斑麻蜥卵每日短期暴露于潜在致死的极端温度下对孵化成功率和孵出幼体形态特征无明显的不利效应; (2)温度波动对孵出幼体运动表现无促进作用,对孵化期的影响则不同于平均值相同的恒定温度。     

The effects of thermal and hydric environments on hatching success, embryonic use of energy and hatchling traits in a colubrid snake, Elaphe carinata.

We examined the effects of thermal and hydric environments on hatching success, the embryonic use of energy and hatchling traits in a colubrid snake, Elaphe carinata. The eggs were incubated at four temperatures ranging from 24 to 32 degrees C on substrates with water potentials of 0 and -220 kPa using a 4x2 factorial design. Both thermal and hydric environments affected the water exchange between eggs and their surroundings. Eggs incubated in wetter substrates gained mass throughout the course of incubation, whereas eggs in drier substrates gained mass during the first half of incubation and lost mass thereafter. Hatching success was noticeably higher at 26 and 30 degrees C than at 24 and 32 degrees C, but among treatments, differences in hatching success were not significant. Temperature significantly affected the duration of incubation and most hatchling traits examined. Deformed hatchlings were found in all temperature treatments, with more deformities observed at 32 degrees C. Hatchlings from eggs incubated at different temperatures differed in wet body mass, but the differences stemmed mainly from variation in water contents. Embryos at different temperatures completed development at nearly the same expenditure of energy and catabolized nearly the same amount of lipids, but hatchlings from different temperatures differed in the development condition of carcass at hatching. Hatchlings from eggs incubated at 26 degrees C were larger in SVL than those from other higher or lower incubation temperatures, characteristically having larger carcasses; hatchlings from 32 degrees C eggs were smaller in SVL and had smaller carcasses but larger residual yolks than those from lower incubation temperatures. Hatchlings from eggs incubated at 24 degrees C were shorter in tail length but greater in size (SVL)-specific body wet mass than those from higher incubation temperatures. Within the range from -220 to 0 kPa, the substrate water potential did not affect hatching success, the embryonic use of energy and all hatchling traits examined, and the effects of temperature were independent of the effects of substrate water potential. Therefore, our data add evidence showing that embryonic development in reptiles with pliable-shelled eggs is relatively insensitive to variation in hydric environments during incubation.     

Incubation of rigid-shelled turtle eggs: do hydric conditions matter?

Rigid-shelled eggs of the broad-shelled river turtle Chelodina expansa were incubated at 28 degrees C in wet (-100 kPa), intermediate (-350 kPa) and dry (-750 kPa) conditions. Incubation period was influenced by clutch of origin, but was independent of incubation water potential. Rates of water gained from the environment and pre-pipping egg mass were influenced by incubation water potential -- eggs incubating at higher (less negative) water potentials absorbing more water from their environment. Hatchlings from wet conditions had greater mass but a smaller amount of residual yolk than hatchlings from dry conditions and it is suggested that the amount of yolk converted to tissue is influenced by the amount of water absorbed by the egg during incubation. Water content of yolk-free hatchlings from the -100-kPa treatment was greater than those from the -350-kPa and -750-kPa treatments, but the water content of residual yolks was similar across all hydric conditions.     

Erfahrungsbericht über die Haltung und deutsche Erstzucht der Borneo-Flussschildkröte (Orlitia borneensis Gray, 1873) im Zoo Dresden

Dresden Zoo bred successfully the Malaysian giant turtle (Orlitia borneensis) in summer 2012. This was the first successful breeding of this species in Germany.Little is known about biology and behaviour of this large river turtle and keeping and especially breeding of this endangered species in captivity is a rarity. In order to create optimal breeding conditions Dresden Zoo rebuilt an enclosure for the turtles in 2010. An area with soil and sand was built for the expected egg deposition. After arranged matings one female dug a nest on this area and buried her eggs. Nine eggs were secured and transferred into an incubator in a box filled with a 1:1 mixture of vermiculite and water. The average temperature was 29 °C. After problems with the temperature regulation the damaged incubator had to be replaced. Because of an estimated incubation period of 3–4 months, one egg was opened on day 127 of incubation. A live hatchling with a big yolk sac was fetched. Because of the non-reabsorbed yolk sac the hatchling was further incubated. On day 154 of incubation all eggs were manually opened and the hatchlings were fetched. All of these hatchlings showed a non-reabsorbed yolk sac and were incubated onwards in a box with wet paper towel until the yolk sac was completely reabsorbed. After that the hatchlings were housed solitarily in a box with water of approximately 4 cm height and a small land area. Two days after housing food was offered for the first time. All hatchlings accepted the offered food consisting of herbal as well as of animal products and later turtle pellets and self-made turtle jelly.Though little is known about breeding this species, the breeding success of Dresden Zoo demonstrates a possible approach to this topic. But there are still things to optimize. For example the manual hatching is something that should be avoided in future. Fertilization and hatching rate of 100% are promising and up to date eight out of nine hatchlings are still alive.     

Geographic variation in hatchling size in an oviparous skink: effects of maternal investment and incubation thermal environment

Geographic variation in offspring size can be viewed as an adaptive response to local environmental conditions, but the causes of such variation remain unclear. Here, we compared the size and composition of eggs laid by female Chinese skinks (Plestiodon chinensis) from six geographically distinct populations in southeastern China to evaluate geographic variation in hatchling size. We also incubated eggs from these six populations at three constant temperatures (24, 28 and 32 °C) to evaluate the combined effects of incubation temperature and population source on hatchling size. Egg mass and composition varied among populations, and interpopulation differences in yolk dry mass and energy content were still evident after accounting for egg mass. Population mean egg mass and thus hatchling mass were greater in the colder localities. Females from three northern populations increased offspring size by laying larger eggs relative to their own size. Females from an inland population in Rongjiang could increase offspring size by investing relatively more dry materials and thus more energy into individual eggs without enlarging the size of their eggs. The degree of embryonic development at oviposition was almost the same across the six populations, so was the rate of embryonic development and thus incubation length at any given temperature. Both incubation temperature and population source affected hatchling traits examined, but the relative importance of these two factors varied between traits. Our data show that in P. chinensis hatchling traits reflecting overall body size (body mass, snout‐vent length and tail length) are more profoundly affected by population source. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 283–296.     

Do changing moisture levels during incubation influence phenotypic traits of hatchling snakes (Tropidonophis mairii, Colubridae)?

Phenotypic traits (e.g., size, strength, speed) of hatchlings in many reptile species are influenced by hydric conditions in the nest. Previous experiments have focused on comparisons between eggs maintained under constant (but different) conditions, but eggs in natural nests frequently experience strong temporal shifts in soil water content during incubation. Keelback snakes (Tropidonophis mairii) in the Australian wet-dry tropics nest over most of the year, so early nests experience decreasing water availability during development, late nests experience increases, and others (midyear) remain stable in this respect. We mimicked these three conditions and incubated 54 eggs (nine from each of six clutches) in a split-clutch design to maintain the same average water content but with differing trajectories through incubation. The experimental treatments significantly affected the total amount of water taken up by the eggs (and thus final egg mass), but incubation periods were unaffected. Hatchling size but not strength showed minor but statistically significant effects of incubation regimes. The ability of keelback eggs to take up excess water whenever it becomes available (either early or late in development) and to retain it even when conditions change buffers embryogenesis effectively (but not completely) against fluctuations in soil water conditions.