The brood-parasitic brown-headed cowbird(Molothrus ater)has one of the shortest incubation periods of any bird.Brown-headed cowbird eggs,and those of other avian brood parasites,tend to be more spherical due to their ...The brood-parasitic brown-headed cowbird(Molothrus ater)has one of the shortest incubation periods of any bird.Brown-headed cowbird eggs,and those of other avian brood parasites,tend to be more spherical due to their greater relative width.The traditional explanation for this egg shape is that it,combined with the thicker eggshells,resists host puncture-ejection.However,very few North American hosts of the brownheaded cowbird actually engage in puncture-ejection and therefore wider eggs may instead provide greater contact with a host’s brood patch during incubation,especially in large host nests.We tested whether greater egg width increased mean temperature and reduced temperature variation in brown-headed cowbirds by inserting temperature probes into brown-headed cowbird and house sparrow(Passer domesticus)eggs and placing them into red-winged blackbird(Agelaius phoeniceus)nests.House sparrow eggs are similar in appearance and in length to cowbird eggs,but are not as wide.We found no signifcant relationship between brown-headed cowbird egg width and mean incubation temperature.However,brown-headed cowbird eggs experienced less temperature variation than house sparrow eggs,and within brown-headed cowbird eggs,more spherical eggs experienced less temperature variation when accounting for differences in width.These results suggest that brownheaded cowbirds may have short incubation periods in part because their eggs exhibit less temperature variation over the course of incubation.The brown-headed cowbird’s egg shape may contribute to its accelerated embryonic development rate relative to host eggs of similar size,which explains its ability to hatch in a variety of host nests.展开更多
Avian incubation is characterised by the contact between the eggs and the bird's skin to transfer heat to increase egg temperature above ambient conditions. Birds can be attentive to the clutch all of the time or,...Avian incubation is characterised by the contact between the eggs and the bird's skin to transfer heat to increase egg temperature above ambient conditions. Birds can be attentive to the clutch all of the time or, particularly if only one parent incubates, attentiveness may be quite low. Attentiveness is related to egg size with large eggs having high attentiveness, whereas small eggs (<10 g) can have attentiveness ranging from 50% to 100%. Previous studies have suggested that incubation duration is a function of attentiveness albeit for small birds. This study tested the hypothesis that, after controlling for egg size and phylogeny, incubation duration would be a function of attentiveness. Data for 444 bird species representing 24 orders were analysed. Whilst egg mass had a significant relationship with incubation duration, there was no relationship with attentiveness for all of the species or a subset of the passerines. Despite egg temperature drops during an incubation recess, average day-time and night-time temperatures are similar in a range of species. Re-examination of previously reported temperature profiles recorded by dummy eggs over a 24-h period shows that after an incubation recess there seems to be an additional heat flux that raises egg temperature above that seen during night-time periods of constant incubation. The reasons why eggs under intermittent incubation are not considerably cooler than eggs during constant incubation are discussed.展开更多
Embryonic development is a critical period for phenotype formation.Environmental variation during embryonic development can induce changes in postnatal phenotypes of animals.The thyroxine secretion and aerobic metabol...Embryonic development is a critical period for phenotype formation.Environmental variation during embryonic development can induce changes in postnatal phenotypes of animals.The thyroxine secretion and aerobic metabolic activity of small birds are important phenotypes closely related to their winter survival.In the context of climate change,it is necessary to determine whether temperature variation during incubation in birds leads to developmental plasticity of these cold responsive phenotypes.We incubated Japanese Quail(Coturnix japonica)eggs at 36.8℃,37.8℃,and 38.8℃,and raised the chicks to 35-day old at 22℃with same raising conditions,then all the quails were exposed to gradually temperature dropping environment(from 15℃to 0℃).After cold treatment,serum T3 level,resting metabolic rate,skeletal muscle and liver metabolomes of the birds were measured.The serum T3 levels were significantly lower in the 38.8℃group and significantly higher in the 36.8℃group compared to the 37.8℃group.The metabolic rate in the 38.8℃group was significantly lower compared to the 37.8℃group.Compared with the 37.8℃group,metabolites involved in the tricarboxylic acid cycle in the liver were significantly lower in the 38.8℃group,and metabolites related to lipid oxidation metabolism and fatty acid biosynthesis were significantly lower in the skeletal muscles in the 38.8℃group but significantly higher in the 36.8℃group.These results indicate that incubation temperature variation can lead to developmental plasticity in cold responsive physiological phenotypes.Higher incubation temperature may impair the capacity of birds coping with cold challenge.展开更多
Weather conditions play a pivotal role in embryo development and parental incubation costs,potentially impacting the clutch size and incubation behavior of birds.Understanding these effects is crucial for bird conserv...Weather conditions play a pivotal role in embryo development and parental incubation costs,potentially impacting the clutch size and incubation behavior of birds.Understanding these effects is crucial for bird conservation.Reeves’ s Pheasant(Syrmaticus reevesii) is a threatened species endemic to China,which is characterized by female-only incubation.However,there is a lack of information regarding the impact of weather conditions on clutch size and incubation behavior in this species.Using satellite tracking,we tracked 27 wild female Reeves’ s Pheasants from 2020 to 2023 in Hubei Province,China.We explored their clutch size and incubation behavior,as well as their responses to ambient temperature and precipitation.Clutch size averaged 7.75 ±1.36,had an association with average ambient temperature and average daily precipitation during the egglaying period,and was potentially linked to female breeding attempts.Throughout the incubation period,females took an average of 0.73 ±0.46 recesses every 24 h,with an average recess duration of 100.80 ±73.37 min and an average nest attendance of 92.98 ±5.27%.They showed a unimodal recess pattern in which nest departures peaked primarily between 13:00 and 16:00.Furthermore,females rarely left nests when daily precipitation was high.Recess duration and nest attendance were influenced by the interaction between daily mean ambient temperature and daily precipitation,as well as day of incubation.Additionally,there was a positive correlation between clutch size and recess duration.These results contribute valuable insights into the lifehistory features of this endangered species.展开更多
Growth indicators including weight, body length, wings length, tail length, tarsus, gape, the third toe and head width of 21 nestlings of Great Bustard (Otis tarda) were measured and investigated in Harbin Zoo, Harbin...Growth indicators including weight, body length, wings length, tail length, tarsus, gape, the third toe and head width of 21 nestlings of Great Bustard (Otis tarda) were measured and investigated in Harbin Zoo, Harbin, China during 1999-2002, and methods on successfully fostering nestlings of the bird were also summarized in this article. The results showed: the Great Bustard is a kind of premature bird and its birth weight was 86.31?.56g (N=21); environmental temperature for the neonatal nestlings should be controlled at 36C; the feeding principle having many meals but little food at each for the nestlings should be followed; since six weeks after birth, nestlings of both gender began to show significant difference in body weight, the weight of male was 1.8 times of that of the female after fourteenth week, and by weight and body figure sexual identity could be easily discerned when 3 or 4 months old; There is no significant difference in growth and development of all organs between male and female nestlings and organ growth curves were fit into Logistic equation.展开更多
The incubation layer with amorphous structure between the substrate and crystalline layer may obviously affect the performance for a microcrystalline Si thin film transistor (μc-Si TFT),especially for the bottom gate...The incubation layer with amorphous structure between the substrate and crystalline layer may obviously affect the performance for a microcrystalline Si thin film transistor (μc-Si TFT),especially for the bottom gate TFT(BG-TFT).It is found that decreasing the ratio of SiH 4/(H 2+SiH 4) is an effective way to decrease the incubation layer thickness of μc-Si directly deposited by VHF PECVD without any further thermal or laser treatment.Based on the μc-Si with a thin incubation layer,the BG-TFT with Al/SiN x/μc-Si/n+-μc-Si/Al structure is fabricated.The ratio of on-state current to off-state current is up to 106,the mobility is around 0.7cm2/(V·s),and the threshold voltage is about 5V.展开更多
We incubated eggs of five Phrynocephalus species （P. albolineatus, P. axillaries, P. grumgrzimailoi, P. helioscopus and P. przewalskii） at three constant temperatures （24℃, 28℃ and 32℃） to examine differences i...We incubated eggs of five Phrynocephalus species （P. albolineatus, P. axillaries, P. grumgrzimailoi, P. helioscopus and P. przewalskii） at three constant temperatures （24℃, 28℃ and 32℃） to examine differences in incubation length and hatchling morphology among species and among temperature treatments. We combined data from this study with those reported previously for P. frontalis and P. versicolor to examine whether embryonic stage at laying is a causal factor for interspecific variation in incubation length, and whether the phylogenetic relationship inferred from hatchling morphology is consistent with the relationship based on mitochondrial DNA data. Mean values for incubation length differed among the five species studied herein and, in all these five species, incubation length decreased at a decreasing rate as temperature increased. In none of the five species did hatchling size （snout-vent length and body mass） and other morphological variables differ among the three temperature treatments. The seven oviparous Phrynocephalus lizards found in China differ from each other in hatchling morphology, and embryonic stage at laying is a causal factor of inter- and intra-specific variation in incubation length. The phylogenetic relationship inferred from hatchling morphology is not always consistent with the currently known relationship based on mitochondrial DNA data. Data from this study and those reported previously allow the conclusion that any Phrynocephalus species may have its unique position along the axis defined by hatchling morphology.展开更多
Phenotypic plasticity and local adaptation are viewed as the main factors that result in between-population variation in phenotypic traits,but contributions of these factors to phenotypic variation vary between traits...Phenotypic plasticity and local adaptation are viewed as the main factors that result in between-population variation in phenotypic traits,but contributions of these factors to phenotypic variation vary between traits and between species and have only been explored in a few species of reptiles.Here,we incubated eggs of the Chinese skink(Plestiodon chinensis)from 7 geographically separated populations in Southeast China at 3 constant temperatures(24,28,and 32℃)to evaluate the combined effects of dutch origin,source population,and incubation temperature on hatchling traits.The relative importance of these factors varied between traits.Nearly all examined hatchling traits,including body mass,snout-vent length(SVL),tail length,head size,limb length,tympanum diameter,and locomotor speed,varied among populations and were affected by incubation temperature.Measures for hatchling size(body mass and SVL)varied considerably among clutches.Source population explained much of the variation in hatchling body mass,whereas incubation temperature explained much of the variation in other examined traits.Our results indicate that between-population variation in hatchling traits of P.chinensis likely reflects the difference in natural incubation conditions and genetic divergence.展开更多
An incubation experiment with soil water content treatments of 0.15 （W1）, 0.20 （W2）, and 0.40 （W3） g g^-1 soil was carried out for two months to investigate the activities of important enzymes involved in C, N, ...An incubation experiment with soil water content treatments of 0.15 （W1）, 0.20 （W2）, and 0.40 （W3） g g^-1 soil was carried out for two months to investigate the activities of important enzymes involved in C, N, P, and S cycling in a paddy soil from the Taihu Lake region, China, under waterlogged and aerobic conditions. Compared with air-dried soil, waterlogging resulted in a significant decrease （P ≤ 0.05） of fluorescein diacetate （FDA） and /3-D-glucosidase activities, and this effect was enhanced with increasing waterlogging time. Waterlogging also significantly inhibited （P ≤ 0.05） arylsulfatase as well as alkaline and acid phosphatase activities, but did not decrease the activities with the increase in waterlogging time. Short-term waterlogging did not affect urease activity, but prolonged waterlogging decreased it markedly. In contrast, the aerobic incubation （W1 and W2 treatments） significantly increased （P ≤ 0.05） FDA, alkaline phosphatase, and /3-D-glucosidase activities. With aerobic treatments the activities of FDA and alkaline phosphatase increased with incubation time, whereas /3-D-glucosidase activity decreased. A significant difference （P ≤ 0.05） was usually observed between the W1 and W2 treatments for the activities of FDA as well as alkaline and acid phosphatase; however,/3-D-glucosidase and urease were usually not significant （P ≤ 0.05）. No activity differences were observed between waterlogging and aerobic incubation for arylsulfatase and urease.展开更多
The soil moisture regime can affect the release of heavy metals in soil. In the previous studies, slightly polluted soils or artificially contaminated soil samples were considered to investigate the effect of soil moi...The soil moisture regime can affect the release of heavy metals in soil. In the previous studies, slightly polluted soils or artificially contaminated soil samples were considered to investigate the effect of soil moisture. We used highly smelter-contaminated and aged soils to study the release of typical heavy metals(Cu, Zn, Cd and Pb) induced by water incubation in batch experiments with characterization via speciation and X-ray diffraction analyses(XRD). The results show that the leachable concentrations of the heavy metals increased slightly in the first 30 days, decreased drastically between 30 and 90 days, and immobilized relatively constant thereafter. The fluctuation was ascribed to the changes of soil Eh and pH, the reductive dissolution of crystalline iron oxides, the formation of new amorphous iron oxides, the absorption of dissolved organic matter and the precipitation of metal sulfide. Speciation analysis indicated that a proportion of the soil heavy metals was transformed from an exchangeable fraction to a less labile fraction after water incubation. And the presence of a lead iron oxide phase and the peak increasing of zinc sulfide were observed via XRD analyses. Finally, water incubation restrained the release of heavy metals after 180 days of incubation, and reduced the leachability of Cu, Zn, Cd and Pb by as much as 1.61%–7.21% for soil A and 0.43%–3.36% for soil B, respectively. The study findings have implications for the formulation of risk control and management strategies for heavy metals in smelter-contaminated soils.展开更多
The incubation layers in microcrystalline silicon films （μc-Si：H） are studied in detail. The incubation layers in μc- Si：H films are investigated by biracial Raman spectra, and the results indicate that either d...The incubation layers in microcrystalline silicon films （μc-Si：H） are studied in detail. The incubation layers in μc- Si：H films are investigated by biracial Raman spectra, and the results indicate that either decreasing silane concentration （SC） or increasing plasma power can reduce the thickness of incubation layer. The analysis of the in-situ diagnosis by plasma optical emission spectrum （OES） shows that the emission intensities of the SiH＊（412 nm） and Hα （656 nm） lines are time-dependent, thus SiH＊/Hα ratio is of temporal evolution. The variation of SiH＊/Hα ratio can indicate the variation in relative concentration of precursor and atomic hydrogen in the plasma. And the atomic hydrogen plays a crucial role in the formation of μc-Si：H; thus, with the plasma excited, the temporal-evolution SiH＊/Hα ratio has a great influence on the formation of an incubation layer in the initial growth stage. The fact that decreasing the SC or increasing the plasma power can decrease the SIH＊/Hα ratio is used to explain why the thickness of incubation layer can reduce with decreasing the SC or increasing the plasma power.展开更多
To test the hypothesis that the variance of incubation temperature may have constituted a significant selective force for reptilian viviparity, we incubated eggs of the slender forest skink Scincella modesta in five t...To test the hypothesis that the variance of incubation temperature may have constituted a significant selective force for reptilian viviparity, we incubated eggs of the slender forest skink Scincella modesta in five thermally different natural nests and at two constant temperatures （18℃ and 21 ℃）. Our manipulation of incubation temperature had significant effects on incubation length and several hatchling traits （snout-vent length, tail length, fore-limb length, and sprint speed）, but not on hatching success and other hatchling traits examined （body mass, head size, and hind-limb length）. Incubation length was nonlinearly sensitive to temperature, but it was not correlated with the thermal variance when holding the thermal mean constant. The 18 ℃ treatment not only produced smaller sized hatchlings but also resulted in decreased sprint speed. Eggs in the nest with the greatest proportion of temperatures higher than 28 ℃ also produced smaller sized hatchlings. None of the hatchling traits examined was affected by the thermal variance. Thermal fluctuations did result in longer incubation times, but females would benefit little from maintaining stable body temperatures or selecting thermally stable nests in terms of the reduced incubation length. Our data show that the mean rather than the variance of temperatures has a key role in influencing incubation length and hatchling phenotypes, and thus do not support the hypothesis tested .展开更多
We incubated eggs ofPlestiodon chinensis under five constant （24, 26, 28, 30, and 32 ℃） and one fluctuating thermal regimes to examine the effects of constant versus fluctuating incubation temperatures on hatching ...We incubated eggs ofPlestiodon chinensis under five constant （24, 26, 28, 30, and 32 ℃） and one fluctuating thermal regimes to examine the effects of constant versus fluctuating incubation temperatures on hatching success, incubation length, and hatchling morphology. The duration of incubation varied considerably among the six temperature treatments, whereas hatching success did not. The mean incubation length decreased as temperature increased in a nonlinear way, and increased as the thermal variance increased. Incubation temperature affected the body size （linear length and mass） and shape of hatchlings, with eggs incubated at 26, 28, and 30 ℃ producing larger and heavier hatchlings than did those incubated at 24 ℃, 32 ℃, or fluctuating temperatures. Our results showed that exposure of P. chinensis eggs to extreme temperatures for brief periods of time did not increase embryonic mortality and, in the fluctuating-temperature treatment, the thermal variance affected hatchling morphology more evidently than the thermal mean. Our results highlight the importance of the thermal variance in affecting embryonic development and hatchling morphology, and add further evidence that temperatures within the range of 26-30 ℃ are optimal for P. chinensis embryos.展开更多
This paper outlines the results of experimental study of the dynamic rock failure based on the comparison of dry and saturated limestone samples obtained during the dynamic compression and split tests. The tests were ...This paper outlines the results of experimental study of the dynamic rock failure based on the comparison of dry and saturated limestone samples obtained during the dynamic compression and split tests. The tests were performed using the Kolsky method and its modifications for dynamic splitting. The mechanical data(e.g. strength, time and energy characteristics) of this material at high strain rates are obtained. It is shown that these characteristics are sensitive to the strain rate. A unified interpretation of these rate effects, based on the structuraletemporal approach, is hereby presented. It is demonstrated that the temporal dependence of the dynamic compressive and split tensile strengths of dry and saturated limestone samples can be predicted by the incubation time criterion. Previously discovered possibilities to optimize(minimize) the energy input for the failure process is discussed in connection with industrial rock failure processes. It is shown that the optimal energy input value associated with critical load, which is required to initialize failure in the rock media, strongly depends on the incubation time and the impact duration. The optimal load shapes, which minimize the momentum for a single failure impact, are demonstrated. Through this investigation, a possible approach to reduce the specific energy required for rock cutting by means of high-frequency vibrations is also discussed.展开更多
Flexible-shelled eggs of the lizards Phrynocephalus przewalskii and P. versicolor were incubated under different thermal and hydric conditions to elicit the effects of incubation environment on hatching success, embry...Flexible-shelled eggs of the lizards Phrynocephalus przewalskii and P. versicolor were incubated under different thermal and hydric conditions to elicit the effects of incubation environment on hatching success, embryonic development and duration as well as hatchling phenotypes. Embryogenesis of the two species was not sensitive to changes in the hydric environment except P. przewalskii incubated in 30°C group. Temperature significantly altered the duration of embryogenesis, with cooler temperatures leading to a longer incubation period. Hatching success was greater at 26 and 30°C than at 34°C. The hatchlings incubated at 26 and 30°C had longer snout-vent length, larger body mass, and better locomotor performance than those incubated at 34°C. Compared to P. przewalskii, P. versicolor had a shorter incubation period and yielded smaller hatchlings, which then had a higher survival rate in cooler and drier habitats. We conclude that an incubation temperature of 30°C would produce the best balance among developmental rate, hatching success, and post-hatching performance. We speculate that the upper temperature limit for incubation of P. versicolor eggs may be slightly higher than 34°C.展开更多
The closed-jar incubation method is widely used to estimate the mineralization of soil organic C. There are two C pools （i.e., organic and inorganic C） in calcareous soil. To evaluate the effect of additional carbon...The closed-jar incubation method is widely used to estimate the mineralization of soil organic C. There are two C pools （i.e., organic and inorganic C） in calcareous soil. To evaluate the effect of additional carbonates on CO2 emission from calcareous soil during closed-jar incubation, three incubation experiments were conducted by adding different types （CaCO3 and MgCO3） and amounts of carbonate to the soil. The addition of carbonates significantly increased CO2 emission from the soil; the increase ranged from 12.0~ in the CaCO3 amended soil to 460~0 in the MgCO3 amended soil during a 100-d incubation. Cumulative CO2 production at the end of the incubation was three times greater in the MgCO3 amended soil compared to the CaCO3 amended one. The CO2 emission increased with the amount of CaCO3 added to the soil. In contrast, CO2 emission decreased as the amount of MgCO3 added to the soil increased. Our results confirmed that the closed-jar incubation method could lead to an overestimate of organic C mineralization in calcareous soils. Because of its effect on soil pH and the dissolution of carbonates, HgC12 should not be used to sterili~.e calcareous soil if the experiment includes the measurement of soil CO2 production.展开更多
Objective To evaluate the infectivity of severe acute respiratory syndrome （SARS） during its incubation period by investigating chains of transmission and individuals isolated for medical observation with a view to ...Objective To evaluate the infectivity of severe acute respiratory syndrome （SARS） during its incubation period by investigating chains of transmission and individuals isolated for medical observation with a view to providing scientific evidence for updating protocols of medical isolation. Methods Individuals related with the two SARS chains of transmission in Beijing in 2003 and a group of individuals isolated for medical observation in Haidian district of Beijing during the SARS outbreak were selected as subjects of study. Contactors with SARS patients and those with symptom development following the contacts were investigated via questionnaire. Serum samples were collected from super transmitters and tested for SARS-CoV antibody by neutralization test and enzyme linked immunosorbent assay （ELISA）. Results A total of 1 112 contactors were investigated in three surveys. Of them, 669 had a history of close contact with symptomatic SARS patients, 101 developed symptoms with a rate of 15.1%, 363 had a history of close contact with patients in their incubation period, none of whom developed symptoms （0%）. Serum samples were collected fi＇om 32 highly-exposed individuals, of whom 13 developing SARS symptoms atter contact had serum samples positive for SARS-CoV antibody. Samples collected from the asymptomatic contactors were all negative for SARS-CoV antibody. Conclusion SARS cases are infectious only during their symptomatic period and are non-infectious during the incubation period. Isolation for medical observation should be placed for individuals who are in close contact with symptomatic SARS patients. The results of our study are of decisive significance for the Ministry of Health to the definition of SARS close contactor.展开更多
Nowadays, most available information on the degradative behaviour of feeds in ruminants is based on in situ incubation in the rumen, and it is adopted by many feed evaluation systems currently in use for ruminants. Ho...Nowadays, most available information on the degradative behaviour of feeds in ruminants is based on in situ incubation in the rumen, and it is adopted by many feed evaluation systems currently in use for ruminants. However, the outcome of.this technique might be affected by many factors such as sequence of nylon bags incubation in the rumen. The objective of current study was to investigate effects of sequence of nylon bag incubation on degradative behavior of dry matter （DM）, crude protein （CP）, neutral detergent fiber （NDF） and acid detergent fiber （ADF） in some feed ingredients commonly used in dairy rations, including alfalfa haylage, corn silage, corn grain and soybean meal. Four multiparous Holstein lactating cows fitted with permanent ruminal cannulas were used. The nylon bags containing feed samples either were placed in the rumen at once and removed at designated time intervals （all in-gradually out method; AG） or were placed in the rumen at designated time points and retrieved at once （gradually in-all out method; GA）. Fractional rate of degradation of potentially degradable fraction, lag time and effective rumen degradability （ED） of DM and CP were significantly higher in the AG compared to the GA method （P〈0.05）. Fractional rates of DM and CP degradation was higher in alfalfa haylage samples incubated in the rumen using the AG method compared to that using the GA method （0.138 h-1 vs. 0.073 h-1 and 0.002 h-1 vs. 0.1125 h-1, for DM and CP, respectively; P〈0.05）. Due to a higher fractional rate of degradation （Kd） of DM and CP, the ED of DM and CP at different fractional passage rates were higher in the AG than those in the GA method （P〈0.05）. Potentially degradable fraction and lag time of NDF were higher in the AG method compared to the GA method （P〈0.05）. Placing all bags in the rumen at once and removing them at designated time intervals compared with introduction of bags in reverse sequence and removing them all at once led to a lower undegradable fraction （U） of NDF in alfalfa （1.8% vs. 4.0%, respectively; P〈0.05） and corn silage （3.3% vs. 6.7%, respectively; P〈0.05） samples. Potentially degradable fraction of ADF was significantly higher in the AG method compared with the GA method （P〈0.05）. Bag incubation sequence had profound effects on kinetics of degradation of DM, CP and NDF in situ in the feed samples studied. The effects were more evident in the forages （especially alfalfa haylage） than in the concentrate ingredientsnamely corn grain and soybean meal..This experiment is the first time to investigate effects of two methods under the same experiment conditions, providing basic data for the determination of ED.展开更多
We studied sexual dimorphism and female reproduction in an oviparous forest skink （Sphenomorphus incognitus） from South China. We incubated eggs under five thermal regimes （22, 25, 28, 25 ± 3 and 27± 5℃...We studied sexual dimorphism and female reproduction in an oviparous forest skink （Sphenomorphus incognitus） from South China. We incubated eggs under five thermal regimes （22, 25, 28, 25 ± 3 and 27± 5℃） to examine the effects of constant versus fluctuating temperatures on incubation length and hatchling morphology. In our sample the largest male and female were 110 mm and 108 mm snout-vent length （SVL）, respectively. Adult males and females did not differ in mean SVL; adult males were larger in head size （both length and width）, longer in fore- and hind-limb lengths and shorter in abdomen length than females of the same SVL. Accordingly, we conclude that S. incognitus is a sexually monomorphic species in terms of SVL but shows sexual dimorphism in head size, abdomen length and appendage length. Females laid a single clutch of 3-10 eggs per breeding season from early May to mid- August, with larger females generally laying more （but not always larger） eggs per clutch than did smaller ones. Embryonic stages at laying ranged from Dufaure and Hubert＇s （1961） stage 31 to 32, with a mean stage of 31.3. The positive relationship between clutch mass and female SVL was not significant. The offspring size-number trade-off does not exist in S, incognitus, as revealed by the fact that egg mass was independent of relative fecundity. Incubation length decreased as temperature increased, and stable temperatures resulted in delayed hatching. Hatchlings incubated under the five thermal regimes did not differ from each other in any examined trait, suggesting that S. incognitus is among oviparous reptilian species where incubation temperature has no role in modifying hatchling morphology as long as eggs are not exposed to extreme temperatures for prolonged periods of time.展开更多
文摘The brood-parasitic brown-headed cowbird(Molothrus ater)has one of the shortest incubation periods of any bird.Brown-headed cowbird eggs,and those of other avian brood parasites,tend to be more spherical due to their greater relative width.The traditional explanation for this egg shape is that it,combined with the thicker eggshells,resists host puncture-ejection.However,very few North American hosts of the brownheaded cowbird actually engage in puncture-ejection and therefore wider eggs may instead provide greater contact with a host’s brood patch during incubation,especially in large host nests.We tested whether greater egg width increased mean temperature and reduced temperature variation in brown-headed cowbirds by inserting temperature probes into brown-headed cowbird and house sparrow(Passer domesticus)eggs and placing them into red-winged blackbird(Agelaius phoeniceus)nests.House sparrow eggs are similar in appearance and in length to cowbird eggs,but are not as wide.We found no signifcant relationship between brown-headed cowbird egg width and mean incubation temperature.However,brown-headed cowbird eggs experienced less temperature variation than house sparrow eggs,and within brown-headed cowbird eggs,more spherical eggs experienced less temperature variation when accounting for differences in width.These results suggest that brownheaded cowbirds may have short incubation periods in part because their eggs exhibit less temperature variation over the course of incubation.The brown-headed cowbird’s egg shape may contribute to its accelerated embryonic development rate relative to host eggs of similar size,which explains its ability to hatch in a variety of host nests.
文摘Avian incubation is characterised by the contact between the eggs and the bird's skin to transfer heat to increase egg temperature above ambient conditions. Birds can be attentive to the clutch all of the time or, particularly if only one parent incubates, attentiveness may be quite low. Attentiveness is related to egg size with large eggs having high attentiveness, whereas small eggs (<10 g) can have attentiveness ranging from 50% to 100%. Previous studies have suggested that incubation duration is a function of attentiveness albeit for small birds. This study tested the hypothesis that, after controlling for egg size and phylogeny, incubation duration would be a function of attentiveness. Data for 444 bird species representing 24 orders were analysed. Whilst egg mass had a significant relationship with incubation duration, there was no relationship with attentiveness for all of the species or a subset of the passerines. Despite egg temperature drops during an incubation recess, average day-time and night-time temperatures are similar in a range of species. Re-examination of previously reported temperature profiles recorded by dummy eggs over a 24-h period shows that after an incubation recess there seems to be an additional heat flux that raises egg temperature above that seen during night-time periods of constant incubation. The reasons why eggs under intermittent incubation are not considerably cooler than eggs during constant incubation are discussed.
基金funded by the National Natural Science Foundation of China(32071515 to S.Z.)Graduate Research and Practice Projects of Minzu University of China(SZKY2024035 to R.Z.)。
文摘Embryonic development is a critical period for phenotype formation.Environmental variation during embryonic development can induce changes in postnatal phenotypes of animals.The thyroxine secretion and aerobic metabolic activity of small birds are important phenotypes closely related to their winter survival.In the context of climate change,it is necessary to determine whether temperature variation during incubation in birds leads to developmental plasticity of these cold responsive phenotypes.We incubated Japanese Quail(Coturnix japonica)eggs at 36.8℃,37.8℃,and 38.8℃,and raised the chicks to 35-day old at 22℃with same raising conditions,then all the quails were exposed to gradually temperature dropping environment(from 15℃to 0℃).After cold treatment,serum T3 level,resting metabolic rate,skeletal muscle and liver metabolomes of the birds were measured.The serum T3 levels were significantly lower in the 38.8℃group and significantly higher in the 36.8℃group compared to the 37.8℃group.The metabolic rate in the 38.8℃group was significantly lower compared to the 37.8℃group.Compared with the 37.8℃group,metabolites involved in the tricarboxylic acid cycle in the liver were significantly lower in the 38.8℃group,and metabolites related to lipid oxidation metabolism and fatty acid biosynthesis were significantly lower in the skeletal muscles in the 38.8℃group but significantly higher in the 36.8℃group.These results indicate that incubation temperature variation can lead to developmental plasticity in cold responsive physiological phenotypes.Higher incubation temperature may impair the capacity of birds coping with cold challenge.
基金supported by the National Natural Science Foundation of China (grant number 31872240)。
文摘Weather conditions play a pivotal role in embryo development and parental incubation costs,potentially impacting the clutch size and incubation behavior of birds.Understanding these effects is crucial for bird conservation.Reeves’ s Pheasant(Syrmaticus reevesii) is a threatened species endemic to China,which is characterized by female-only incubation.However,there is a lack of information regarding the impact of weather conditions on clutch size and incubation behavior in this species.Using satellite tracking,we tracked 27 wild female Reeves’ s Pheasants from 2020 to 2023 in Hubei Province,China.We explored their clutch size and incubation behavior,as well as their responses to ambient temperature and precipitation.Clutch size averaged 7.75 ±1.36,had an association with average ambient temperature and average daily precipitation during the egglaying period,and was potentially linked to female breeding attempts.Throughout the incubation period,females took an average of 0.73 ±0.46 recesses every 24 h,with an average recess duration of 100.80 ±73.37 min and an average nest attendance of 92.98 ±5.27%.They showed a unimodal recess pattern in which nest departures peaked primarily between 13:00 and 16:00.Furthermore,females rarely left nests when daily precipitation was high.Recess duration and nest attendance were influenced by the interaction between daily mean ambient temperature and daily precipitation,as well as day of incubation.Additionally,there was a positive correlation between clutch size and recess duration.These results contribute valuable insights into the lifehistory features of this endangered species.
文摘Growth indicators including weight, body length, wings length, tail length, tarsus, gape, the third toe and head width of 21 nestlings of Great Bustard (Otis tarda) were measured and investigated in Harbin Zoo, Harbin, China during 1999-2002, and methods on successfully fostering nestlings of the bird were also summarized in this article. The results showed: the Great Bustard is a kind of premature bird and its birth weight was 86.31?.56g (N=21); environmental temperature for the neonatal nestlings should be controlled at 36C; the feeding principle having many meals but little food at each for the nestlings should be followed; since six weeks after birth, nestlings of both gender began to show significant difference in body weight, the weight of male was 1.8 times of that of the female after fourteenth week, and by weight and body figure sexual identity could be easily discerned when 3 or 4 months old; There is no significant difference in growth and development of all organs between male and female nestlings and organ growth curves were fit into Logistic equation.
文摘The incubation layer with amorphous structure between the substrate and crystalline layer may obviously affect the performance for a microcrystalline Si thin film transistor (μc-Si TFT),especially for the bottom gate TFT(BG-TFT).It is found that decreasing the ratio of SiH 4/(H 2+SiH 4) is an effective way to decrease the incubation layer thickness of μc-Si directly deposited by VHF PECVD without any further thermal or laser treatment.Based on the μc-Si with a thin incubation layer,the BG-TFT with Al/SiN x/μc-Si/n+-μc-Si/Al structure is fabricated.The ratio of on-state current to off-state current is up to 106,the mobility is around 0.7cm2/(V·s),and the threshold voltage is about 5V.
基金supported by grants from the National Natural Science Foundation of China (31071910 and 31200282)Priority Academic Program Development of Jiangsu Higher Education Institutions and High Academic Talent Foundation of Nanjing Forestry University (GXL201306)
文摘We incubated eggs of five Phrynocephalus species （P. albolineatus, P. axillaries, P. grumgrzimailoi, P. helioscopus and P. przewalskii） at three constant temperatures （24℃, 28℃ and 32℃） to examine differences in incubation length and hatchling morphology among species and among temperature treatments. We combined data from this study with those reported previously for P. frontalis and P. versicolor to examine whether embryonic stage at laying is a causal factor for interspecific variation in incubation length, and whether the phylogenetic relationship inferred from hatchling morphology is consistent with the relationship based on mitochondrial DNA data. Mean values for incubation length differed among the five species studied herein and, in all these five species, incubation length decreased at a decreasing rate as temperature increased. In none of the five species did hatchling size （snout-vent length and body mass） and other morphological variables differ among the three temperature treatments. The seven oviparous Phrynocephalus lizards found in China differ from each other in hatchling morphology, and embryonic stage at laying is a causal factor of inter- and intra-specific variation in incubation length. The phylogenetic relationship inferred from hatchling morphology is not always consistent with the currently known relationship based on mitochondrial DNA data. Data from this study and those reported previously allow the conclusion that any Phrynocephalus species may have its unique position along the axis defined by hatchling morphology.
基金This work was supported by grants from the National Natural Science Foundation of China(31670399 and 31670422).
文摘Phenotypic plasticity and local adaptation are viewed as the main factors that result in between-population variation in phenotypic traits,but contributions of these factors to phenotypic variation vary between traits and between species and have only been explored in a few species of reptiles.Here,we incubated eggs of the Chinese skink(Plestiodon chinensis)from 7 geographically separated populations in Southeast China at 3 constant temperatures(24,28,and 32℃)to evaluate the combined effects of dutch origin,source population,and incubation temperature on hatchling traits.The relative importance of these factors varied between traits.Nearly all examined hatchling traits,including body mass,snout-vent length(SVL),tail length,head size,limb length,tympanum diameter,and locomotor speed,varied among populations and were affected by incubation temperature.Measures for hatchling size(body mass and SVL)varied considerably among clutches.Source population explained much of the variation in hatchling body mass,whereas incubation temperature explained much of the variation in other examined traits.Our results indicate that between-population variation in hatchling traits of P.chinensis likely reflects the difference in natural incubation conditions and genetic divergence.
基金Project supported by the National Basic Research Program of China (No. G1999011808) and the National Natural Science Foundation of China (No. 40371066).
文摘An incubation experiment with soil water content treatments of 0.15 （W1）, 0.20 （W2）, and 0.40 （W3） g g^-1 soil was carried out for two months to investigate the activities of important enzymes involved in C, N, P, and S cycling in a paddy soil from the Taihu Lake region, China, under waterlogged and aerobic conditions. Compared with air-dried soil, waterlogging resulted in a significant decrease （P ≤ 0.05） of fluorescein diacetate （FDA） and /3-D-glucosidase activities, and this effect was enhanced with increasing waterlogging time. Waterlogging also significantly inhibited （P ≤ 0.05） arylsulfatase as well as alkaline and acid phosphatase activities, but did not decrease the activities with the increase in waterlogging time. Short-term waterlogging did not affect urease activity, but prolonged waterlogging decreased it markedly. In contrast, the aerobic incubation （W1 and W2 treatments） significantly increased （P ≤ 0.05） FDA, alkaline phosphatase, and /3-D-glucosidase activities. With aerobic treatments the activities of FDA and alkaline phosphatase increased with incubation time, whereas /3-D-glucosidase activity decreased. A significant difference （P ≤ 0.05） was usually observed between the W1 and W2 treatments for the activities of FDA as well as alkaline and acid phosphatase; however,/3-D-glucosidase and urease were usually not significant （P ≤ 0.05）. No activity differences were observed between waterlogging and aerobic incubation for arylsulfatase and urease.
基金supported by the China National Public Welfare Program for Environmental Protection(No.201509031)The Hi-Tech Research and Development Program(863)of China(No.2013AA06A206)supported by the State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences
文摘The soil moisture regime can affect the release of heavy metals in soil. In the previous studies, slightly polluted soils or artificially contaminated soil samples were considered to investigate the effect of soil moisture. We used highly smelter-contaminated and aged soils to study the release of typical heavy metals(Cu, Zn, Cd and Pb) induced by water incubation in batch experiments with characterization via speciation and X-ray diffraction analyses(XRD). The results show that the leachable concentrations of the heavy metals increased slightly in the first 30 days, decreased drastically between 30 and 90 days, and immobilized relatively constant thereafter. The fluctuation was ascribed to the changes of soil Eh and pH, the reductive dissolution of crystalline iron oxides, the formation of new amorphous iron oxides, the absorption of dissolved organic matter and the precipitation of metal sulfide. Speciation analysis indicated that a proportion of the soil heavy metals was transformed from an exchangeable fraction to a less labile fraction after water incubation. And the presence of a lead iron oxide phase and the peak increasing of zinc sulfide were observed via XRD analyses. Finally, water incubation restrained the release of heavy metals after 180 days of incubation, and reduced the leachability of Cu, Zn, Cd and Pb by as much as 1.61%–7.21% for soil A and 0.43%–3.36% for soil B, respectively. The study findings have implications for the formulation of risk control and management strategies for heavy metals in smelter-contaminated soils.
文摘The incubation layers in microcrystalline silicon films （μc-Si：H） are studied in detail. The incubation layers in μc- Si：H films are investigated by biracial Raman spectra, and the results indicate that either decreasing silane concentration （SC） or increasing plasma power can reduce the thickness of incubation layer. The analysis of the in-situ diagnosis by plasma optical emission spectrum （OES） shows that the emission intensities of the SiH＊（412 nm） and Hα （656 nm） lines are time-dependent, thus SiH＊/Hα ratio is of temporal evolution. The variation of SiH＊/Hα ratio can indicate the variation in relative concentration of precursor and atomic hydrogen in the plasma. And the atomic hydrogen plays a crucial role in the formation of μc-Si：H; thus, with the plasma excited, the temporal-evolution SiH＊/Hα ratio has a great influence on the formation of an incubation layer in the initial growth stage. The fact that decreasing the SC or increasing the plasma power can decrease the SIH＊/Hα ratio is used to explain why the thickness of incubation layer can reduce with decreasing the SC or increasing the plasma power.
基金The work was carried out in compliance with the current laws of China, and was supported by grant from Priority Academic Program Development of Jiangsu Higher Education Institutions to Ji＇s group, the Natural Science Foundation of the Jiangsu Higher Education Institutions of China （Project No. llKJB180004）, Jiangsu Provincial Foundation of Natural Science （No. BK2012849） and the Natural Science Foundation of China （No. 31070339）. We would like to thank Long-Hui Lin, Jian-Fang Gao, Lai-Gao Luo andYan-Fu Qu for their assistance both in the field and in the laboratory.
文摘To test the hypothesis that the variance of incubation temperature may have constituted a significant selective force for reptilian viviparity, we incubated eggs of the slender forest skink Scincella modesta in five thermally different natural nests and at two constant temperatures （18℃ and 21 ℃）. Our manipulation of incubation temperature had significant effects on incubation length and several hatchling traits （snout-vent length, tail length, fore-limb length, and sprint speed）, but not on hatching success and other hatchling traits examined （body mass, head size, and hind-limb length）. Incubation length was nonlinearly sensitive to temperature, but it was not correlated with the thermal variance when holding the thermal mean constant. The 18 ℃ treatment not only produced smaller sized hatchlings but also resulted in decreased sprint speed. Eggs in the nest with the greatest proportion of temperatures higher than 28 ℃ also produced smaller sized hatchlings. None of the hatchling traits examined was affected by the thermal variance. Thermal fluctuations did result in longer incubation times, but females would benefit little from maintaining stable body temperatures or selecting thermally stable nests in terms of the reduced incubation length. Our data show that the mean rather than the variance of temperatures has a key role in influencing incubation length and hatchling phenotypes, and thus do not support the hypothesis tested .
基金the National Natural Science Foundation of China (31470471 and 30670281)the Zhejiang Provincial Natural Science Foundation (LY17C030003)the Priority Academic Development Program of Jiangsu Higher Education Institutions
文摘We incubated eggs ofPlestiodon chinensis under five constant （24, 26, 28, 30, and 32 ℃） and one fluctuating thermal regimes to examine the effects of constant versus fluctuating incubation temperatures on hatching success, incubation length, and hatchling morphology. The duration of incubation varied considerably among the six temperature treatments, whereas hatching success did not. The mean incubation length decreased as temperature increased in a nonlinear way, and increased as the thermal variance increased. Incubation temperature affected the body size （linear length and mass） and shape of hatchlings, with eggs incubated at 26, 28, and 30 ℃ producing larger and heavier hatchlings than did those incubated at 24 ℃, 32 ℃, or fluctuating temperatures. Our results showed that exposure of P. chinensis eggs to extreme temperatures for brief periods of time did not increase embryonic mortality and, in the fluctuating-temperature treatment, the thermal variance affected hatchling morphology more evidently than the thermal mean. Our results highlight the importance of the thermal variance in affecting embryonic development and hatchling morphology, and add further evidence that temperatures within the range of 26-30 ℃ are optimal for P. chinensis embryos.
基金supported by IHC Merwede B.V. as well as by Russian Foundation for Basic Research (Grant Nos. 13-0100349 and 14-01-31510)Russian Science Foundation (“support and development”, Grant No. 14-19-01637)Saint Petersburg University (Grant No. 6.38.243.2014)
文摘This paper outlines the results of experimental study of the dynamic rock failure based on the comparison of dry and saturated limestone samples obtained during the dynamic compression and split tests. The tests were performed using the Kolsky method and its modifications for dynamic splitting. The mechanical data(e.g. strength, time and energy characteristics) of this material at high strain rates are obtained. It is shown that these characteristics are sensitive to the strain rate. A unified interpretation of these rate effects, based on the structuraletemporal approach, is hereby presented. It is demonstrated that the temporal dependence of the dynamic compressive and split tensile strengths of dry and saturated limestone samples can be predicted by the incubation time criterion. Previously discovered possibilities to optimize(minimize) the energy input for the failure process is discussed in connection with industrial rock failure processes. It is shown that the optimal energy input value associated with critical load, which is required to initialize failure in the rock media, strongly depends on the incubation time and the impact duration. The optimal load shapes, which minimize the momentum for a single failure impact, are demonstrated. Through this investigation, a possible approach to reduce the specific energy required for rock cutting by means of high-frequency vibrations is also discussed.
基金funded by the National Natural Science Foundation of China(NSFC 31071918)
文摘Flexible-shelled eggs of the lizards Phrynocephalus przewalskii and P. versicolor were incubated under different thermal and hydric conditions to elicit the effects of incubation environment on hatching success, embryonic development and duration as well as hatchling phenotypes. Embryogenesis of the two species was not sensitive to changes in the hydric environment except P. przewalskii incubated in 30°C group. Temperature significantly altered the duration of embryogenesis, with cooler temperatures leading to a longer incubation period. Hatching success was greater at 26 and 30°C than at 34°C. The hatchlings incubated at 26 and 30°C had longer snout-vent length, larger body mass, and better locomotor performance than those incubated at 34°C. Compared to P. przewalskii, P. versicolor had a shorter incubation period and yielded smaller hatchlings, which then had a higher survival rate in cooler and drier habitats. We conclude that an incubation temperature of 30°C would produce the best balance among developmental rate, hatching success, and post-hatching performance. We speculate that the upper temperature limit for incubation of P. versicolor eggs may be slightly higher than 34°C.
基金Supported by the National Natural Science Foundation of China(Nos.40571087 and 40773057)the National Key Technologies Research and Development Program of China during the 11th Five-Year Plan Period(No.2007BAD89B02)
文摘The closed-jar incubation method is widely used to estimate the mineralization of soil organic C. There are two C pools （i.e., organic and inorganic C） in calcareous soil. To evaluate the effect of additional carbonates on CO2 emission from calcareous soil during closed-jar incubation, three incubation experiments were conducted by adding different types （CaCO3 and MgCO3） and amounts of carbonate to the soil. The addition of carbonates significantly increased CO2 emission from the soil; the increase ranged from 12.0~ in the CaCO3 amended soil to 460~0 in the MgCO3 amended soil during a 100-d incubation. Cumulative CO2 production at the end of the incubation was three times greater in the MgCO3 amended soil compared to the CaCO3 amended one. The CO2 emission increased with the amount of CaCO3 added to the soil. In contrast, CO2 emission decreased as the amount of MgCO3 added to the soil increased. Our results confirmed that the closed-jar incubation method could lead to an overestimate of organic C mineralization in calcareous soils. Because of its effect on soil pH and the dissolution of carbonates, HgC12 should not be used to sterili~.e calcareous soil if the experiment includes the measurement of soil CO2 production.
文摘Objective To evaluate the infectivity of severe acute respiratory syndrome （SARS） during its incubation period by investigating chains of transmission and individuals isolated for medical observation with a view to providing scientific evidence for updating protocols of medical isolation. Methods Individuals related with the two SARS chains of transmission in Beijing in 2003 and a group of individuals isolated for medical observation in Haidian district of Beijing during the SARS outbreak were selected as subjects of study. Contactors with SARS patients and those with symptom development following the contacts were investigated via questionnaire. Serum samples were collected from super transmitters and tested for SARS-CoV antibody by neutralization test and enzyme linked immunosorbent assay （ELISA）. Results A total of 1 112 contactors were investigated in three surveys. Of them, 669 had a history of close contact with symptomatic SARS patients, 101 developed symptoms with a rate of 15.1%, 363 had a history of close contact with patients in their incubation period, none of whom developed symptoms （0%）. Serum samples were collected fi＇om 32 highly-exposed individuals, of whom 13 developing SARS symptoms atter contact had serum samples positive for SARS-CoV antibody. Samples collected from the asymptomatic contactors were all negative for SARS-CoV antibody. Conclusion SARS cases are infectious only during their symptomatic period and are non-infectious during the incubation period. Isolation for medical observation should be placed for individuals who are in close contact with symptomatic SARS patients. The results of our study are of decisive significance for the Ministry of Health to the definition of SARS close contactor.
基金the financial supports of the National Natural Science Foundation of China(30901030,31372334)the Key Technologies R&D Program of China(2012BAD12B02)the Program for Beijing Excellent Talents,China(2013D009007000003)
文摘Nowadays, most available information on the degradative behaviour of feeds in ruminants is based on in situ incubation in the rumen, and it is adopted by many feed evaluation systems currently in use for ruminants. However, the outcome of.this technique might be affected by many factors such as sequence of nylon bags incubation in the rumen. The objective of current study was to investigate effects of sequence of nylon bag incubation on degradative behavior of dry matter （DM）, crude protein （CP）, neutral detergent fiber （NDF） and acid detergent fiber （ADF） in some feed ingredients commonly used in dairy rations, including alfalfa haylage, corn silage, corn grain and soybean meal. Four multiparous Holstein lactating cows fitted with permanent ruminal cannulas were used. The nylon bags containing feed samples either were placed in the rumen at once and removed at designated time intervals （all in-gradually out method; AG） or were placed in the rumen at designated time points and retrieved at once （gradually in-all out method; GA）. Fractional rate of degradation of potentially degradable fraction, lag time and effective rumen degradability （ED） of DM and CP were significantly higher in the AG compared to the GA method （P〈0.05）. Fractional rates of DM and CP degradation was higher in alfalfa haylage samples incubated in the rumen using the AG method compared to that using the GA method （0.138 h-1 vs. 0.073 h-1 and 0.002 h-1 vs. 0.1125 h-1, for DM and CP, respectively; P〈0.05）. Due to a higher fractional rate of degradation （Kd） of DM and CP, the ED of DM and CP at different fractional passage rates were higher in the AG than those in the GA method （P〈0.05）. Potentially degradable fraction and lag time of NDF were higher in the AG method compared to the GA method （P〈0.05）. Placing all bags in the rumen at once and removing them at designated time intervals compared with introduction of bags in reverse sequence and removing them all at once led to a lower undegradable fraction （U） of NDF in alfalfa （1.8% vs. 4.0%, respectively; P〈0.05） and corn silage （3.3% vs. 6.7%, respectively; P〈0.05） samples. Potentially degradable fraction of ADF was significantly higher in the AG method compared with the GA method （P〈0.05）. Bag incubation sequence had profound effects on kinetics of degradation of DM, CP and NDF in situ in the feed samples studied. The effects were more evident in the forages （especially alfalfa haylage） than in the concentrate ingredientsnamely corn grain and soybean meal..This experiment is the first time to investigate effects of two methods under the same experiment conditions, providing basic data for the determination of ED.
基金the National Natural Science Foundation of China (31470471)the Priority Academic Development Program of Jiangsu Higher Education Institutions and the Innovation of Graduate Student Training Project of Jiangsu Province (KYLX15_0737)
文摘We studied sexual dimorphism and female reproduction in an oviparous forest skink （Sphenomorphus incognitus） from South China. We incubated eggs under five thermal regimes （22, 25, 28, 25 ± 3 and 27± 5℃） to examine the effects of constant versus fluctuating temperatures on incubation length and hatchling morphology. In our sample the largest male and female were 110 mm and 108 mm snout-vent length （SVL）, respectively. Adult males and females did not differ in mean SVL; adult males were larger in head size （both length and width）, longer in fore- and hind-limb lengths and shorter in abdomen length than females of the same SVL. Accordingly, we conclude that S. incognitus is a sexually monomorphic species in terms of SVL but shows sexual dimorphism in head size, abdomen length and appendage length. Females laid a single clutch of 3-10 eggs per breeding season from early May to mid- August, with larger females generally laying more （but not always larger） eggs per clutch than did smaller ones. Embryonic stages at laying ranged from Dufaure and Hubert＇s （1961） stage 31 to 32, with a mean stage of 31.3. The positive relationship between clutch mass and female SVL was not significant. The offspring size-number trade-off does not exist in S, incognitus, as revealed by the fact that egg mass was independent of relative fecundity. Incubation length decreased as temperature increased, and stable temperatures resulted in delayed hatching. Hatchlings incubated under the five thermal regimes did not differ from each other in any examined trait, suggesting that S. incognitus is among oviparous reptilian species where incubation temperature has no role in modifying hatchling morphology as long as eggs are not exposed to extreme temperatures for prolonged periods of time.
