We collected 75 adult Tonkin forest skinks(Sphenomorphus tonkinensis) from Hainan, South China and incubated eggs at four constant temperatures ranging from 22 ℃ to 28 ℃ to study sexual dimorphism, female reproducti...We collected 75 adult Tonkin forest skinks(Sphenomorphus tonkinensis) from Hainan, South China and incubated eggs at four constant temperatures ranging from 22 ℃ to 28 ℃ to study sexual dimorphism, female reproductive characteristics and embryonic thermosensitivity. The largest male was 53.4 mm snout-vent length(SVL), and the largest female was 54.3 mm SVL. The mean SVL was slightly greater in adult females(49.9 mm) than in adult males(48.8 mm), but the difference was not significant.Head length, head width, fore-limb length and hindlimb length were longer in adult males and abdomen length was longer in adult females after accounting for SVL. Accordingly, we conclude that S. tonkinensis is basically a sexually size-monomorphic species with sexual dimorphism in head size, abdomen(trunk)length and limb size. Females laid up to two clutches of 1–4 eggs each per egg-laying season from February to May. Egg mass, clutch size and clutch mass were independent of female SVL. Embryonic stages at laying varied from Dufaure and Hubert’s stage 30 to 31. With female SVL held constant, the negative correlation between egg mass and clutch size was not significant, suggesting that the offspring(egg) sizenumber trade-off between is not evident or eggs are well optimized for size in S. tonkinensis. None of the eggs at 28 ℃ hatched;hatching success was lower at 22 ℃ than at 24 ℃ or 26 ℃. The mean incubation length was 52.9 d at 22 ℃, 40.4 d at 24 ℃ and 33.6 d at 26 ℃. Hatchlings from eggs incubated at 22 ℃,24 ℃ and 26 ℃ did not differ morphologically at hatching, suggesting that temperatures within this range do not differentially affect hatchling morphology in S. tonkinensis.展开更多
The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducin...The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducing the energy consumption of reproduction or other costly tissues should compensate for the cost of a large brain.Egg production in birds requires a large proportion of the total energy budget,and a clutch mass in some bird species can outweigh the body mass of the female.To date,this hypothesis has mainly been tested in mammals and ectothermic animals such as anurans and fishes.We collated data on adult brain size,body mass and eggproduction traits such as clutch size,egg mass and annual broods from published studies,and conducted a phylogenetic comparative test of the interplay between egg-production investment and brain size evolution across bird species.After controlling for phylogenetic relationships and body size,we find a negative correlation between brain size and clutch size across 1395 species,which favored ETH.However,when egg mass was integrated in models,positive associations were detected between brain size and mass of eggs(via egg mass,clutch mass and annual total egg mass).Our results suggest that brain size trades off against egg-production only via certain aspects(e.g.,clutch size).By contrast,a positive relationship between brain size and total egg reproduction(e.g.,clutch mass and annual total egg mass) implied increased total energy budget outweighing energy allocation across bird species.Our study shows that there is no general energy trade-off between brain size and eggreproduction investment,and suggests that brain size evolution follows mixed strategies across bird species.展开更多
We maintained gravid Chinese skinks(Plestiodon chinensis) at three constant temperatures(25, 28 and 31 °C) during gestation, and randomly assigned eggs from each female to one of the same three temperatures for i...We maintained gravid Chinese skinks(Plestiodon chinensis) at three constant temperatures(25, 28 and 31 °C) during gestation, and randomly assigned eggs from each female to one of the same three temperatures for incubation to determine maternal thermal effects on female reproduction and hatchling phenotype. Maternal temperature affected egg-laying date, hatching success and hatchling linear size(snout-vent length, SVL) but not clutch size, egg size, egg component, and embryonic stage at laying. More specifically, females at higher temperatures laid eggs earlier than did those at low temperatures, eggs laid at 31 °C were less likely to hatch than those laid at 25 °C or 28 °C, and hatchlings from eggs laid at 31 °C were smaller in SVL. Our finding that maternal temperature(pre-ovipositional thermal condition) rather than incubation temperature(post-ovipositional thermal condition) affected hatching success indicated that embryos at early stages were more vulnerable to temperature than those at late stages. Our data provide an inference that moderate maternal temperatures enhance reproductive fitness in P. chinensis.展开更多
The effect of both male and female age was investigated on certain reproductive attributes, viz. mating incidence, mating duration, fecundity, percent egg viability, ratio of reproductive and non-reproductive periods ...The effect of both male and female age was investigated on certain reproductive attributes, viz. mating incidence, mating duration, fecundity, percent egg viability, ratio of reproductive and non-reproductive periods and reproductive rate, of an aphidophagous ladybird, Cheilomenes sexmaculata （Fabricius）. Females started mating at the age of 8 hours post-emergence （PE） and males at the age of 2 days PE. Mating in the laboratory was a maledominated phenomenon. The mating duration and reproductive rate of 10-day-old females when mated with males of varying ages increased up to the male age of 60 days, and thereafter decreased, whereas, fecundity, egg viability and ratio of reproductive and non-reproductive periods increased up to the male age of 50 days, and thereafter declined. However, when females of varying ages were mated with 10-day-old males, fecundity and reproductive rate increased up to 40 days of female age, respectively, then decreased. The ratio of reproductive and non-reproductive periods increased with increasing age of females. Mating age for optimal reproductive output was 10-50-day-old males and NE to 40-day-old females. Reproductive cessation in males was recorded after 50 days PE, whereas in females at the age of 40 days PE. Higher mating durations lead to elevated reproductive rates. Delay in the reproductive phase was positively correlated with longevity. The results of this study may aid mass multiplication of this ladybird by identifying and promoting usage of adults of optimal age, Our results also enhance our understanding of the effect of age on reproductive attributes in ladybirds.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
Background:The broodstock diet,and in particular the lipid and fatty acid composition of the diet,is known to play a key role in reproductive efficiency and survival of the progeny in fish.A major problem when replaci...Background:The broodstock diet,and in particular the lipid and fatty acid composition of the diet,is known to play a key role in reproductive efficiency and survival of the progeny in fish.A major problem when replacing both fish meal and fish oil by plant sources is the lack of n-3 long chain polyunsaturated fatty acids,such as eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA).To address this problem,we studied the effect of the plant-based diet supplemented with Schizochytrium sp.microalgae,source of DHA,compared to a conventional commercial diet rich in fish meal and fish oil on reproductive performance and egg quality and the consequences on progeny,in female rainbow trout broodstock.Results:The results demonstrated that DHA-rich microalgae supplementation in a plant-based diet allowed for the maintenance of reproductive performance and egg quality comparable to a conventional commercial feed rich in fish meal and fish oil and led to an increased significant fry survival after resorption.Moreover,when females were fed a plant-based diet supplemented with micro-algae,the 4-month-old progenies showed a significant higher growth when they were challenged with a similar diet as broodstock during 1 month.We provide evidence for metabolic programming in which the maternal dietary induced significant protracted effects on lipid metabolism of progeny.Conclusions:The present study demonstrates that supplementation of a plant-based diet with DHA-rich microalgae can be an effective alternative to fish meal and fish oil in rainbow trout broodstock aquafeed.展开更多
The structural and histochemical changes of the egg apparatus in the polyembryonic rice ( Oryza sativa L.), ApⅢ with the highest frequence of additional embryos among the polyembryonic rice investigated, before an...The structural and histochemical changes of the egg apparatus in the polyembryonic rice ( Oryza sativa L.), ApⅢ with the highest frequence of additional embryos among the polyembryonic rice investigated, before and after fertilization were studied and compared with those of normal and other polyembryonic rices in a similar developmental period. A total of 2 932 ovules were observed and each of them contained only a single embryo sac with a set of egg apparatus. Among 1 655 embryo sacs, there were 1 643 embryo sacs (99.27%) with one normal egg apparatus in each embryo sac, and only 12 embryo sacs (0.73%) from the remainder with 4_celled egg apparatus, i.e. two eggs and two synergids. Neither the numerous poly_egg apparatus and egg_like cells, nor the double set of embryo sacs each containing one egg apparatus and other abnormal egg apparatus in single ovary, which were reported by earlier investigators to have high frequency of embryo production in SB_1 and ApⅣ, were observed. The egg cell was located at the subterminal site of the micropylar end of embryo sac. The cytoplasm of egg cell was rich in protein materials and polysaccharide grains, which did not disappear until the division of zygote. The prominent nucleus was closely surrounded by protein and polysaccharide grains, which did not disappear until the division of zygote. No cytological difference was found between egg cells from the normal and abnormal egg apparatus. The two synergids were fully developed and situated at the upper most part of the micropylar end of the mature embryo sac. In most embryo sacs, the synergids were flask_shaped with longer necks, and a widened cap_shaped top, in close contact with the micropyle. The synergids had a well developed filiform apparatus. The characteristic appearance of the filiform apparatus as well as the cap_neck region of synergids before and after pollen tube penetration were easily distinguishable from the egg cell. The structure, the stainability with Coomassie Brilliant Blue and PAS reaction, the pro展开更多
Amphibians show a variety of reproductive modes and strategies. The cyclicity and continuity of reproduction can often be predicted from the annual gonadosomatic index trends in a species specific manner. This researc...Amphibians show a variety of reproductive modes and strategies. The cyclicity and continuity of reproduction can often be predicted from the annual gonadosomatic index trends in a species specific manner. This research aims to document the female and male gonadosomatic index profiles and to ascertain the reproductive cyclicity or continuity of Fejervarya lirnnocharis （Anura： Ranidae） caught in Mac Sot, Tak Province, Thailand. Frogs were collected monthly between November 2007 and October 2009 in rice fields and their surrounding areas in the study site. For each frog, total weight and ovarian/testicular weight were measured to obtain the female and male gonadosomatic index. The number of female individuals with mature eggs （postvitellogenic eggs） was also counted. The results showed that female frogs had two main surges of increased GSI in March and September of 2008. Alternatively, male frogs showed a more gradual increase and decrease in gonadosomatic index, thus the index remaining high throughout the year. This study concluded that while F. limnocharis in this area is essentially a continuous breeder, it is more optimized for a cyclic reproduction mode with two breeding cycles during the rainy season.展开更多
基金This work was supported by grants from the Special Foundation for Basic Work of the Science and Technology Ministry of China(2022FY100500-2)Hainan Key Program of Science and Technology(ZDXM20110008)Hainan Specially Supporting Discipline of Zoology。
文摘We collected 75 adult Tonkin forest skinks(Sphenomorphus tonkinensis) from Hainan, South China and incubated eggs at four constant temperatures ranging from 22 ℃ to 28 ℃ to study sexual dimorphism, female reproductive characteristics and embryonic thermosensitivity. The largest male was 53.4 mm snout-vent length(SVL), and the largest female was 54.3 mm SVL. The mean SVL was slightly greater in adult females(49.9 mm) than in adult males(48.8 mm), but the difference was not significant.Head length, head width, fore-limb length and hindlimb length were longer in adult males and abdomen length was longer in adult females after accounting for SVL. Accordingly, we conclude that S. tonkinensis is basically a sexually size-monomorphic species with sexual dimorphism in head size, abdomen(trunk)length and limb size. Females laid up to two clutches of 1–4 eggs each per egg-laying season from February to May. Egg mass, clutch size and clutch mass were independent of female SVL. Embryonic stages at laying varied from Dufaure and Hubert’s stage 30 to 31. With female SVL held constant, the negative correlation between egg mass and clutch size was not significant, suggesting that the offspring(egg) sizenumber trade-off between is not evident or eggs are well optimized for size in S. tonkinensis. None of the eggs at 28 ℃ hatched;hatching success was lower at 22 ℃ than at 24 ℃ or 26 ℃. The mean incubation length was 52.9 d at 22 ℃, 40.4 d at 24 ℃ and 33.6 d at 26 ℃. Hatchlings from eggs incubated at 22 ℃,24 ℃ and 26 ℃ did not differ morphologically at hatching, suggesting that temperatures within this range do not differentially affect hatchling morphology in S. tonkinensis.
基金National Natural Science Foun-dation of China(Grant No.32170481 and Grant No.3221153042).
文摘The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducing the energy consumption of reproduction or other costly tissues should compensate for the cost of a large brain.Egg production in birds requires a large proportion of the total energy budget,and a clutch mass in some bird species can outweigh the body mass of the female.To date,this hypothesis has mainly been tested in mammals and ectothermic animals such as anurans and fishes.We collated data on adult brain size,body mass and eggproduction traits such as clutch size,egg mass and annual broods from published studies,and conducted a phylogenetic comparative test of the interplay between egg-production investment and brain size evolution across bird species.After controlling for phylogenetic relationships and body size,we find a negative correlation between brain size and clutch size across 1395 species,which favored ETH.However,when egg mass was integrated in models,positive associations were detected between brain size and mass of eggs(via egg mass,clutch mass and annual total egg mass).Our results suggest that brain size trades off against egg-production only via certain aspects(e.g.,clutch size).By contrast,a positive relationship between brain size and total egg reproduction(e.g.,clutch mass and annual total egg mass) implied increased total energy budget outweighing energy allocation across bird species.Our study shows that there is no general energy trade-off between brain size and eggreproduction investment,and suggests that brain size evolution follows mixed strategies across bird species.
基金the National Science Foundation of China (31670399 and 31670422)
文摘We maintained gravid Chinese skinks(Plestiodon chinensis) at three constant temperatures(25, 28 and 31 °C) during gestation, and randomly assigned eggs from each female to one of the same three temperatures for incubation to determine maternal thermal effects on female reproduction and hatchling phenotype. Maternal temperature affected egg-laying date, hatching success and hatchling linear size(snout-vent length, SVL) but not clutch size, egg size, egg component, and embryonic stage at laying. More specifically, females at higher temperatures laid eggs earlier than did those at low temperatures, eggs laid at 31 °C were less likely to hatch than those laid at 25 °C or 28 °C, and hatchlings from eggs laid at 31 °C were smaller in SVL. Our finding that maternal temperature(pre-ovipositional thermal condition) rather than incubation temperature(post-ovipositional thermal condition) affected hatching success indicated that embryos at early stages were more vulnerable to temperature than those at late stages. Our data provide an inference that moderate maternal temperatures enhance reproductive fitness in P. chinensis.
文摘The effect of both male and female age was investigated on certain reproductive attributes, viz. mating incidence, mating duration, fecundity, percent egg viability, ratio of reproductive and non-reproductive periods and reproductive rate, of an aphidophagous ladybird, Cheilomenes sexmaculata （Fabricius）. Females started mating at the age of 8 hours post-emergence （PE） and males at the age of 2 days PE. Mating in the laboratory was a maledominated phenomenon. The mating duration and reproductive rate of 10-day-old females when mated with males of varying ages increased up to the male age of 60 days, and thereafter decreased, whereas, fecundity, egg viability and ratio of reproductive and non-reproductive periods increased up to the male age of 50 days, and thereafter declined. However, when females of varying ages were mated with 10-day-old males, fecundity and reproductive rate increased up to 40 days of female age, respectively, then decreased. The ratio of reproductive and non-reproductive periods increased with increasing age of females. Mating age for optimal reproductive output was 10-50-day-old males and NE to 40-day-old females. Reproductive cessation in males was recorded after 50 days PE, whereas in females at the age of 40 days PE. Higher mating durations lead to elevated reproductive rates. Delay in the reproductive phase was positively correlated with longevity. The results of this study may aid mass multiplication of this ladybird by identifying and promoting usage of adults of optimal age, Our results also enhance our understanding of the effect of age on reproductive attributes in ladybirds.
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.
基金funded by FEAMP(NutriEgg N°PFEA470016FA1000002).
文摘Background:The broodstock diet,and in particular the lipid and fatty acid composition of the diet,is known to play a key role in reproductive efficiency and survival of the progeny in fish.A major problem when replacing both fish meal and fish oil by plant sources is the lack of n-3 long chain polyunsaturated fatty acids,such as eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA).To address this problem,we studied the effect of the plant-based diet supplemented with Schizochytrium sp.microalgae,source of DHA,compared to a conventional commercial diet rich in fish meal and fish oil on reproductive performance and egg quality and the consequences on progeny,in female rainbow trout broodstock.Results:The results demonstrated that DHA-rich microalgae supplementation in a plant-based diet allowed for the maintenance of reproductive performance and egg quality comparable to a conventional commercial feed rich in fish meal and fish oil and led to an increased significant fry survival after resorption.Moreover,when females were fed a plant-based diet supplemented with micro-algae,the 4-month-old progenies showed a significant higher growth when they were challenged with a similar diet as broodstock during 1 month.We provide evidence for metabolic programming in which the maternal dietary induced significant protracted effects on lipid metabolism of progeny.Conclusions:The present study demonstrates that supplementation of a plant-based diet with DHA-rich microalgae can be an effective alternative to fish meal and fish oil in rainbow trout broodstock aquafeed.
文摘The structural and histochemical changes of the egg apparatus in the polyembryonic rice ( Oryza sativa L.), ApⅢ with the highest frequence of additional embryos among the polyembryonic rice investigated, before and after fertilization were studied and compared with those of normal and other polyembryonic rices in a similar developmental period. A total of 2 932 ovules were observed and each of them contained only a single embryo sac with a set of egg apparatus. Among 1 655 embryo sacs, there were 1 643 embryo sacs (99.27%) with one normal egg apparatus in each embryo sac, and only 12 embryo sacs (0.73%) from the remainder with 4_celled egg apparatus, i.e. two eggs and two synergids. Neither the numerous poly_egg apparatus and egg_like cells, nor the double set of embryo sacs each containing one egg apparatus and other abnormal egg apparatus in single ovary, which were reported by earlier investigators to have high frequency of embryo production in SB_1 and ApⅣ, were observed. The egg cell was located at the subterminal site of the micropylar end of embryo sac. The cytoplasm of egg cell was rich in protein materials and polysaccharide grains, which did not disappear until the division of zygote. The prominent nucleus was closely surrounded by protein and polysaccharide grains, which did not disappear until the division of zygote. No cytological difference was found between egg cells from the normal and abnormal egg apparatus. The two synergids were fully developed and situated at the upper most part of the micropylar end of the mature embryo sac. In most embryo sacs, the synergids were flask_shaped with longer necks, and a widened cap_shaped top, in close contact with the micropyle. The synergids had a well developed filiform apparatus. The characteristic appearance of the filiform apparatus as well as the cap_neck region of synergids before and after pollen tube penetration were easily distinguishable from the egg cell. The structure, the stainability with Coomassie Brilliant Blue and PAS reaction, the pro
基金part of a graduate research project titled "Using the Rice Frog (Fejervarya limnocharis) as Sentinel Species for Cadmium Contamination in Tak Province, Thailand"supported by the National Center of Excellence for Environmental and Hazardous Waste Management (NCE-EHWM)+2 种基金the 90th Anniversary of Chulalongkorn University Fund and a new staff development grant (Ratchadaphiseksomphot Endowment Fund)the MUA-TRF researchgrant (MRG4980120) to Noppadon KITANAsupport was also obtained from NIH Fogarty ITREOH (D43TW007849)
文摘Amphibians show a variety of reproductive modes and strategies. The cyclicity and continuity of reproduction can often be predicted from the annual gonadosomatic index trends in a species specific manner. This research aims to document the female and male gonadosomatic index profiles and to ascertain the reproductive cyclicity or continuity of Fejervarya lirnnocharis （Anura： Ranidae） caught in Mac Sot, Tak Province, Thailand. Frogs were collected monthly between November 2007 and October 2009 in rice fields and their surrounding areas in the study site. For each frog, total weight and ovarian/testicular weight were measured to obtain the female and male gonadosomatic index. The number of female individuals with mature eggs （postvitellogenic eggs） was also counted. The results showed that female frogs had two main surges of increased GSI in March and September of 2008. Alternatively, male frogs showed a more gradual increase and decrease in gonadosomatic index, thus the index remaining high throughout the year. This study concluded that while F. limnocharis in this area is essentially a continuous breeder, it is more optimized for a cyclic reproduction mode with two breeding cycles during the rainy season.
