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
The present study aims to determine,by histological examination,the female reproductive cycle of specimens of Kulzer’s rock lizards collected in a mountainous region in Lebanon.Females of Phoenicolacerta kulzeri foll...The present study aims to determine,by histological examination,the female reproductive cycle of specimens of Kulzer’s rock lizards collected in a mountainous region in Lebanon.Females of Phoenicolacerta kulzeri followed a seasonal reproductive pattern.Winter hibernation period lasted for 5 months.Females of P.Kulzeri exhibited a reproductive activity during spring characterized by the presence of vitellogenic follicles in the ovaries and eggs in the oviducts.Oviposition occurred throughout the springtime.Up to two clutches were produced with an average clutch size of 2.9 eggs.Clutch size was significantly correlated to female body size.The attainment of sexual maturity was at a minimum size of 46 mm snout-vent length.The mean body size of adult females was 55.0 mm and did not differ significantly from that of adult males.Females showed a period of sexual rest in summer and none of them showed a reproductive activity in autumn.The female reproductive activity of P.kulzeri was well-synchronized with that of the males in spring;however,an autumnal asynchrony was observed between the female and male reproductive cycles,since males continued to exhibit a spermatogenetic activity.展开更多
Low-elevation species can migrate toward higher elevations to survive in a warming world.However,animals’responses to hypoxia when migrating to high elevations have rarely been addressed.To identify the response of l...Low-elevation species can migrate toward higher elevations to survive in a warming world.However,animals’responses to hypoxia when migrating to high elevations have rarely been addressed.To identify the response of lowelevation lizards to high-elevation hypoxia,we collected field body temperatures(Tfb)and operative temperatures(Te)of lizards(Eremias argus)from a low-elevation population(1036 m)and a high-elevation population(2036 m),and then determined adult thermal physiology,embryonic development,and hatchling phenotypes after acclimating low-elevation lizards and incubating their eggs in conditions mimicking the low-elevation oxygen condition(18.5%O2)and high-elevation oxygen(hypoxic)condition(16.5%O2).Our study revealed that Tfb and Te were higher for the low-elevation population compared to the high-elevation population.We also found adults from low elevation acclimated to hypoxia preferred lower body temperatures,but did not show changes in locomotor performance or growth.In addition,hypoxia did not affect embryonic development(hatching time and success)or hatchling phenotypes(body size and locomotor performance).These results suggest that adult lizards from low elevations can respond to hypoxia-induced stress when migrating to high elevations by behaviorally thermoregulating to lower body temperatures in order to sustain normal functions.Similarly,low-elevation embryos can develop normally(with unchanged hatching success and offspring phenotypes)under the high-elevation hypoxic condition.This study highlights that low-elevation populations of a species that inhabits a range of elevations can buffer the impact of high-elevation hypoxic conditions to some degree and thus attain similar fitness to the source population.展开更多
Oxidative stress is a key physiological mechanism underlying life-history tradeoffs. Here, I use meta-analytic techniques to test whether sexual differences in oxidative balance are common in vertebrates and to identi...Oxidative stress is a key physiological mechanism underlying life-history tradeoffs. Here, I use meta-analytic techniques to test whether sexual differences in oxidative balance are common in vertebrates and to identify which factors are associated with such differences. The dataset included 732 effect size estimates from 100 articles （82 species）. Larger unsigned effect size （meaning larger sexual differences in a given marker） occurred in： reptiles and fish; those species that do not pro- vide parental care; and oviparous species. Estimates of signed effect size （positive values meaning higher oxidative stress in males） indicated that females were less resistant to oxidative stress than males in： reptiles while males and females were similar in fish, birds, and mammals; those species that do not provide parental care; and oviparous species. There was no evidence for a significant sexual differentiation in oxidative balance in fish, birds, and mammals. Effect size was not associ- ated with： the number of offspring; whether the experimental animals were reproducing or not; biomarker （oxidative damage, non-enzymatic, or enzymatic antioxidant）, the species body mass; the strain （wild vs. domestic）; or the study environment （wild vs. captivity）. Oxidative stress tended to be higher in females than males across most of the tissues analyzed. Levels of residual heterogeneity were high in all models tested. The findings of this meta-analysis indicate that diversification of reproductive strategies might be associated with sexual differences in oxidative balance. This explorative meta-analysis offers a starting platform for future research to investigate the rela-tionship between sex and oxidative balance further.展开更多
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.
文摘The present study aims to determine,by histological examination,the female reproductive cycle of specimens of Kulzer’s rock lizards collected in a mountainous region in Lebanon.Females of Phoenicolacerta kulzeri followed a seasonal reproductive pattern.Winter hibernation period lasted for 5 months.Females of P.Kulzeri exhibited a reproductive activity during spring characterized by the presence of vitellogenic follicles in the ovaries and eggs in the oviducts.Oviposition occurred throughout the springtime.Up to two clutches were produced with an average clutch size of 2.9 eggs.Clutch size was significantly correlated to female body size.The attainment of sexual maturity was at a minimum size of 46 mm snout-vent length.The mean body size of adult females was 55.0 mm and did not differ significantly from that of adult males.Females showed a period of sexual rest in summer and none of them showed a reproductive activity in autumn.The female reproductive activity of P.kulzeri was well-synchronized with that of the males in spring;however,an autumnal asynchrony was observed between the female and male reproductive cycles,since males continued to exhibit a spermatogenetic activity.
基金National Nature and Science Foundation of China(Nos.31870391,31801977)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,No.2019 QZKK0501)Young Elite Scientists Sponsorship Program by CAST,and ISZS for Shuran Li.Bao-Jun Sun is supported by Youth Innovation Promotion Association CAS(no.2019085).
文摘Low-elevation species can migrate toward higher elevations to survive in a warming world.However,animals’responses to hypoxia when migrating to high elevations have rarely been addressed.To identify the response of lowelevation lizards to high-elevation hypoxia,we collected field body temperatures(Tfb)and operative temperatures(Te)of lizards(Eremias argus)from a low-elevation population(1036 m)and a high-elevation population(2036 m),and then determined adult thermal physiology,embryonic development,and hatchling phenotypes after acclimating low-elevation lizards and incubating their eggs in conditions mimicking the low-elevation oxygen condition(18.5%O2)and high-elevation oxygen(hypoxic)condition(16.5%O2).Our study revealed that Tfb and Te were higher for the low-elevation population compared to the high-elevation population.We also found adults from low elevation acclimated to hypoxia preferred lower body temperatures,but did not show changes in locomotor performance or growth.In addition,hypoxia did not affect embryonic development(hatching time and success)or hatchling phenotypes(body size and locomotor performance).These results suggest that adult lizards from low elevations can respond to hypoxia-induced stress when migrating to high elevations by behaviorally thermoregulating to lower body temperatures in order to sustain normal functions.Similarly,low-elevation embryos can develop normally(with unchanged hatching success and offspring phenotypes)under the high-elevation hypoxic condition.This study highlights that low-elevation populations of a species that inhabits a range of elevations can buffer the impact of high-elevation hypoxic conditions to some degree and thus attain similar fitness to the source population.
文摘Oxidative stress is a key physiological mechanism underlying life-history tradeoffs. Here, I use meta-analytic techniques to test whether sexual differences in oxidative balance are common in vertebrates and to identify which factors are associated with such differences. The dataset included 732 effect size estimates from 100 articles （82 species）. Larger unsigned effect size （meaning larger sexual differences in a given marker） occurred in： reptiles and fish; those species that do not pro- vide parental care; and oviparous species. Estimates of signed effect size （positive values meaning higher oxidative stress in males） indicated that females were less resistant to oxidative stress than males in： reptiles while males and females were similar in fish, birds, and mammals; those species that do not provide parental care; and oviparous species. There was no evidence for a significant sexual differentiation in oxidative balance in fish, birds, and mammals. Effect size was not associ- ated with： the number of offspring; whether the experimental animals were reproducing or not; biomarker （oxidative damage, non-enzymatic, or enzymatic antioxidant）, the species body mass; the strain （wild vs. domestic）; or the study environment （wild vs. captivity）. Oxidative stress tended to be higher in females than males across most of the tissues analyzed. Levels of residual heterogeneity were high in all models tested. The findings of this meta-analysis indicate that diversification of reproductive strategies might be associated with sexual differences in oxidative balance. This explorative meta-analysis offers a starting platform for future research to investigate the rela-tionship between sex and oxidative balance further.
