scholarly journals Does the variance of incubation temperatures always constitute a significant selective force for origin of reptilian viviparity?

2012 ◽  
Vol 58 (6) ◽  
pp. 812-819 ◽  
Author(s):  
Hong Li ◽  
Zheng Wang ◽  
Ce Chen ◽  
Xiang Ji
Keyword(s):  
Hind Limb ◽  
Hatching Success ◽  
Incubation Temperature ◽  
Tail Length ◽  
Thermal Fluctuations ◽  
Limb Length ◽  
Selective Force ◽  
Sprint Speed ◽  
The Mean ◽  
Incubation Temperatures

Abstract 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 °C and 21 °C). 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 °C 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 °C 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.

scholarly journals Effects of constant incubation regimes on eggs and hatchlings of the egg-laying skink, Oligosoma suteri

2021 ◽  
Author(s):  
◽  
Kelly Maree Hare
Keyword(s):  
Hatching Success ◽  
Incubation Temperature ◽  
Unit Length ◽  
Condition Index ◽  
Egg Laying ◽  
Maternal Influence ◽  
Temperature Dependent ◽  
Sprint Speed ◽  
Fitness Traits ◽  
Incubation Temperatures

<p>The conditions under which reptilian eggs are incubated affect survival probability and physiological attributes of the progeny. The egg-laying skink, Oligosoma suteri, is the only endemic oviparous lizard in New Zealand. No controlled laboratory incubation had previously been undertaken, and thus no information was available on the requirements for successful captive incubation. I studied the effects of incubation regime on the eggs and hatchlings of O. suteri to four months of age. Oligosoma suteri eggs (n = 174) were randomly distributed among three constant incubation temperatures (18°C, 22°C and 26°C) and two water potentials (-120 kPa and -270 kPa). Hatching success and hatchling survival were greatest at 22°C and 26°C, with hatchlings from 18°C incubation suffering from physical abnormalities. Incubation regime and maternal influence did not affect sex of individuals, with equal sex ratios occurring from each incubation treatment. Hatchlings from the 22°C and -120 kPa incubation treatments were larger, for most measurements, and warmer incubation temperatures resulted in increased growth rates. Juveniles from 22°C and 26°C and individuals with greater mass per unit length (condition index) sprinted faster over 0.25 m. Sprint speed was positively correlated with ambient temperature. At four months of age sprint speed decreased in 18°C individuals and individuals incubated at 26°C and -270 kPa compared to their performance at one month. The results suggest that the most successful captive incubation regime for O. suteri is 22°C and -120 kPa. This study also shows that temperature-dependent sex determination does not occur in O. suteri, but that fitness traits are influenced by incubation temperature.</p>

scholarly journals Effects of constant incubation regimes on eggs and hatchlings of the egg-laying skink, Oligosoma suteri

2021 ◽  
Author(s):  
◽  
Kelly Maree Hare
Keyword(s):  
Hatching Success ◽  
Incubation Temperature ◽  
Unit Length ◽  
Condition Index ◽  
Egg Laying ◽  
Maternal Influence ◽  
Temperature Dependent ◽  
Sprint Speed ◽  
Fitness Traits ◽  
Incubation Temperatures

<p>The conditions under which reptilian eggs are incubated affect survival probability and physiological attributes of the progeny. The egg-laying skink, Oligosoma suteri, is the only endemic oviparous lizard in New Zealand. No controlled laboratory incubation had previously been undertaken, and thus no information was available on the requirements for successful captive incubation. I studied the effects of incubation regime on the eggs and hatchlings of O. suteri to four months of age. Oligosoma suteri eggs (n = 174) were randomly distributed among three constant incubation temperatures (18°C, 22°C and 26°C) and two water potentials (-120 kPa and -270 kPa). Hatching success and hatchling survival were greatest at 22°C and 26°C, with hatchlings from 18°C incubation suffering from physical abnormalities. Incubation regime and maternal influence did not affect sex of individuals, with equal sex ratios occurring from each incubation treatment. Hatchlings from the 22°C and -120 kPa incubation treatments were larger, for most measurements, and warmer incubation temperatures resulted in increased growth rates. Juveniles from 22°C and 26°C and individuals with greater mass per unit length (condition index) sprinted faster over 0.25 m. Sprint speed was positively correlated with ambient temperature. At four months of age sprint speed decreased in 18°C individuals and individuals incubated at 26°C and -270 kPa compared to their performance at one month. The results suggest that the most successful captive incubation regime for O. suteri is 22°C and -120 kPa. This study also shows that temperature-dependent sex determination does not occur in O. suteri, but that fitness traits are influenced by incubation temperature.</p>

scholarly journals Incubation temperatures, hatching success and congenital anomalies in green turtle nests from Guanahacabibes Peninsula, Cuba

2021 ◽  
Vol 4 (4) ◽  
pp. 321-330
Author(s):  
Randy Calderón Peña ◽  
Julia Azanza Ricardo
Keyword(s):  
Congenital Anomalies ◽  
Green Turtle ◽  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Hatching Success ◽  
Incubation Temperature ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Green Turtles ◽  
Incubation Temperatures

Elevated incubation temperatures of sea turtle nests decrease hatching success and alter the resulting hatchlings' morphology. There is an absence of studies assessing the relationships between temperature and hatching success in Cuba, even when they could improve understanding the limits of thermal tolerance in these species. This study evaluated the influence of incubation temperature on hatching success and phenotypic malformations in green turtle hatchlings (Chelonia mydas); and analyzed the temporal variation in hatching success on the studied beaches. In 48 green turtles nests distributed along two beaches, incubation temperature and hatching success were recorded between 2014 and 2019. Increasing incubation temperature caused a decrease in the hatching success and an increase in the frequency of supernumerary scutes. Despite the elevated temperatures (average > 30°C), hatching was higher than 80%. Significant differences in hatching success were only observed among seasons for nests in Antonio Beach (lower values in 2016 and 2019 compared to 2014).

Size-dependent pigmentation-pattern formation in embryos of Alligator mississippiensis : time of initiation of pattern generation mechanism

1990 ◽  
Vol 239 (1296) ◽  
pp. 279-293 ◽  
Keyword(s):  
Pattern Formation ◽  
Incubation Temperature ◽  
Cell Movement ◽  
Tail Length ◽  
Dorsal Side ◽  
Pattern Generation ◽  
Alligator Mississippiensis ◽  
Pigmentation Pattern ◽  
Size Dependent ◽  
Incubation Temperatures

The pigmentation pattern of Alligator mississippiensis was examined. The number of white stripes on the dorsal side of embryos (stages 21–28) and hatchlings from eggs incubated at 30°C (100% females) and 33°C (100% males) was recorded. Total length, nape–rump length and tail length were recorded for each embryo and hatchling. The number of white stripes was affected by incubation temperature but not sex ; hatchlings incubated a t 33°C had two more white stripes than those at 30°C, despite being the same length. Five female hatchlings produced at 33°C by manipulation of the temperature, had the same number of stripes as males that developed under the same incubation temperatures. The appearance of the pigmentation was accelerated in embryos incubated at 33°C, occurring eight days earlier than at 30°C. At the time just before the first signs of pigment deposition, embryos from 33°C were longer than those at 30°C. If the stripe formation is size dependent this explains why hatchlings at 33°C have more stripes than hatchlings from 30°C. The mechanism that produces the stripe patterns is unknown. We describe key elements a pattern formation mechanism must possess to produce such stripes and suggest a possible mechanism, based on cell movement driven by chemotaxis. We apply the mathematical model to dorsal patterning on A . mississippiensis . We show how length at pattern formation is the prime factor in determining stripe number and how the pattern can be formed in the observed anterior–posterior sequence. We present numerical simulations and show that the qualitative behaviour is consistent with the experimental results.

Incubation temperature affects sexual differentiation, incubation time, and posthatching survival in desert tortoises (Gopherus agassizi)

1995 ◽  
Vol 73 (11) ◽  
pp. 2091-2097 ◽  
Author(s):  
Vanessa Lewis-Winokur ◽  
Robert M. Winokur
Keyword(s):  
Sex Ratio ◽  
Incubation Time ◽  
Sexual Differentiation ◽  
Hatching Success ◽  
Incubation Temperature ◽  
Seminiferous Tubules ◽  
Temperature Dependent ◽  
Incubation Temperatures ◽  
Male To Female ◽  
Pivotal Temperature

Eggs of captive desert tortoises. Gopherus agassizi, incubated at six temperatures (25, 27, 28, 29, 29.4, and 31 °C) produced 107 specimens. Eggs incubated at 31 °C resulted in a male to female sex ratio of 5:7; all other incubation temperatures resulted in males only. Histological examination of gonads revealed that the testes of newly hatched to 3-month-old individuals showed incomplete and poorly developed seminiferous tubules. Female gonads showed a thickened cortex. Incubation times were longer at lower temperatures. Both hatching success and hatchling survivorship were lower at lower incubation temperatures. We confirm that temperature-dependent sex determination occurs in desert tortoises and that the pivotal temperature is between 31 and 32 °C.

Influence of incubation temperature and substrate on eggs and embryos of the garden lizard, Calotes versicolor (Daud.)

2002 ◽  
Vol 23 (1) ◽  
pp. 71-82 ◽  
Author(s):  
Srinivas Saidapur ◽  
Rajkumar Radder ◽  
Bhagyashri Shanbhag
Keyword(s):  
Ambient Temperature ◽  
Hatching Success ◽  
Incubation Temperature ◽  
Developmental Rate ◽  
Egg Mass ◽  
Cotton Wool ◽  
Different Temperatures ◽  
Calotes Versicolor ◽  
Periodic Exposure ◽  
Incubation Temperatures

AbstractThe influence of incubation temperature and substrate on hatching success, duration of incubation and hatchlings' traits in Calotes versicolor was studied experimentally. The eggs were incubated in soil at 1) ambient (27°C±2 s), 2) ambient temperature and exposed to 35°C for 1 or 3hrs/day, 3) constant 30°C, 33°C and 35°C. In another experiment soil, sand or cotton wool was used as incubation substrate at ambient temperature. Duration of incubation was inversely related to incubation temperature. Hatching success was high at ambient (93%), at 30°C (89%) and for eggs exposed to 1 hr (94%) or 3 hr/day to 35°C (93%) compared to those at 33°C (59%) and 35°C (53%). Egg mass increased until hatching, but with a temporal difference in the gain at different temperatures. At high temperatures, it increased rapidly. Eggs incubated at ambient temperature and 1 or 3 hrs exposure to 35°C produced hatchlings heavier than their sibs that hatched at 30°C, 33°C or 35°C. Smaller size of hatchlings at higher incubation temperatures was due to early hatching and low utilization of yolk. Incubation substrate had no influence on offspring traits but hatching success was low (84 ± 9%) in cotton wool. Thus, incubation of eggs in soil or sand at ambient temperature with a periodic exposure to high tolerable temperature provides an optimum balance between developmental rate, hatching success and hatchling quality in C. versicolor.

The effect of incubation temperature on egg survival, hatchling traits and embryonic use of energy in the blue-tailed skink, Eumeces elegans

2003 ◽  
Vol 53 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Lu Shou ◽  
Wei-Guo Du ◽  
Ji-Ke Liu
Keyword(s):  
Incubation Temperature ◽  
Tail Length ◽  
Yolk Sac ◽  
The Body ◽  
Effect Of Temperature ◽  
Egg Survival ◽  
Different Temperatures ◽  
The Mean ◽  
Locomotor Capacity ◽  
Hatchling Size

AbstractEggs of the skink, Eumeces elegans were incubated at 24, 27, 30 and 33°C to assess the effect of temperature on hatchling traits and embryonic use of energy. The mean incubation periods of eggs incubated at 24, 27, 30 and 33°C were 44.1, 28.0, 23.6 and 20.0 days, respectively. The mortality of embryos incubated at these temperatures did not differ significantly. The mean snoutvent lengths of hatchlings from 30 and 33°C were smaller than those of hatchlings from 24°C. In contrast, the body masses of hatchlings were not affected by temperature. Incubation temperature can also modify limb lengths of hatchlings. The fore and hind limb lengths of hatchlings from 24°C were longer than those of hatchlings from 33°C. However, tail length and head size (length and width) for hatchlings from different temperatures were similar. The locomotor capacity of hatchlings incubated at 33°C was completely destroyed, whereas that of hatchlings from the other three temperatures did not differ significantly in spite of the existence of differences in hatchling size. Moreover, incubation temperature affected the allocation of energy between carcass and yolk sac in the hatchling, although the overall conversion of energy from eggs to hatchlings was not influenced by temperature. Hatchlings from 30 and 33°C had a less developed carcass and more energy in yolk sac than those from 24°C. Thus, we can conclude that 33°C is not suitable for the incubation of E. elegans eggs, due to damage to the embryo.

scholarly journals The effect of temperature and scarification method on gorse (Ulex europaeus L) seed germination

2003 ◽  
Vol 56 ◽  
pp. 201-205 ◽  
Author(s):  
C.R. Sixtus ◽  
G.D. Hill ◽  
R.R. Scott
Keyword(s):  
Sulphuric Acid ◽  
Incubation Temperature ◽  
Water Immersion ◽  
Hot Water ◽  
Control Treatment ◽  
Effect Of Temperature ◽  
Ulex Europaeus ◽  
The Mean ◽  
Incubation Temperatures ◽  
Germinated Seeds

As part of a study of gorse (Ulex europaeus L) biocontrol the scarification requirements to maximise germination of freshly harvested seed were investigated Both time of immersion in concentrated sulphuric acid (36N) and incubation temperature were critical Optimum incubation temperature was 15C (mean germination 65) The sulphuric acid treatments that gave the highest percentage of germinated seeds were 180 and 210 min immersion with incubation at 15C giving a mean germination of 81 The mean control germination over all incubation temperatures was 10 Hot water immersion did not significantly increase germination when compared with the unscarified control treatment Mechanical scarification gave a mean germination over all temperatures of 35; the highest germination was again at 15C (48)

scholarly journals Management and relocation of nests of Podocnemis expansa (Schweigger, 1812) (Testudines, Podocnemididae) on the Crixás-Açu river, Brazil

2011 ◽  
Vol 71 (4) ◽  
pp. 975-982 ◽  
Author(s):  
AS. Gomes ◽  
PD. Ferreira Júnior
Keyword(s):  
At Risk ◽  
Rainy Season ◽  
Hatching Success ◽  
Incubation Temperature ◽  
Viable Alternative ◽  
Central Brazil ◽  
Podocnemis Expansa ◽  
The Mean ◽  
Palm Fronds ◽  
Artificial Shading

Podocnemis expansa nests in the sandbanks of the Crixás-Açu River in central Brazil during the dry season. With the return of the rainy season, the river banks are once again inundated, flooding nests and eggs and drowning hatchlings. This study evaluated relocation as an alternative to manage nests at risk of flooding. Forty P. expansa nests from four beaches of the Crixás-Açu were relocated to nurseries constructed in tanks filled with sand from the same river. Nine nests were covered with palm fronds to simulate shading conditions and to lower the incubation temperature. The base of the egg chamber was at a depth of 60 cm in all the nests. The duration of incubation varied for sunlit (49.1 ± 2.35 days) and shaded nests (51.7 ± 1.75 days), but did not change with nest position (center or edge of nurseries). Hatching success was 47.3 ± 13.6%, and did not vary significantly with sunlight/shade or nest position. The mean incubation temperature during the thermosensitivity period varied from 33 ± 1.56 °C to 34.1 ± 1.40 °C. The lowest mean temperature during the thermosensitivity period (31.9 ± 0.95 °C) and the highest proportion of males (up to 45% of hatchlings) were observed in a shaded nest. Most sunlit nests produced only females. The results suggest that relocation is a viable alternative in managing nests at risk of flooding during the rainy season in the Crixás-Açu. Moreover, artificial shading was shown to be an option to increase the proportion of males.

EFFECT OF PLATE INCUBATION TEMPERATURE ON BACTERIAL COUNTS OF GRADE A RAW MILK1

1973 ◽  
Vol 36 (3) ◽  
pp. 152-154 ◽  
Author(s):  
H. E. Randolph ◽  
B. K. Chakraborty ◽  
Otto Hampton ◽  
D. L. Bogart
Keyword(s):  
Incubation Temperature ◽  
Statistical Significance ◽  
Correlation Coefficients ◽  
Raw Milk ◽  
Plate Count ◽  
Bacterial Counts ◽  
Standard Plate Count ◽  
Standard Plate ◽  
The Mean ◽  
Incubation Temperatures

Bacterial counts on 155 raw milk samples obtained with plate incubation temperatures of 27 and 32 C were closely correlated (r = 0.96) . Correlation coefficients between counts obtained at both 27 and 32 C and psychrotrophic (7 C-10 days) counts for all samples were relatively low, but statistically significant ( P &lt; 0.01). The correlation to psychrotrophic counts was especially low and in some instances lacking in statistical significance in the sample groups with counts ( 27 and 32 C) &lt;100,000/ml. Eighty-four of the samples had higher counts at 32 C and 62 samples had higher counts at 27 C. The mean psychrotrophic count of the samples with higher counts at 27 C was higher than the mean psychrotrophic count of the other samples. However, the correlation coefficients were higher for samples with counts higher at 32 C. Incubation at 27 C does not appear to offer significant advantages over the 32 C incubation temperature used in the Standard Plate Count.

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