Numerous bird species have adapted to rapid urbanization,navigating challenges introduced by novel stressors.While prior research has explored how urban exploiters adjust their physiology relative to their rural count...Numerous bird species have adapted to rapid urbanization,navigating challenges introduced by novel stressors.While prior research has explored how urban exploiters adjust their physiology relative to their rural counterparts during breeding season,the modulation of multiple physiological markers outside of reproduction,and the maintenance of sex-specific differences,remain less understood.Using an urban exploiter,the Eurasian tree sparrow(ETS;Passer montanus),we investigated how both sexes of urban and rural populations modulate twenty-two physiological markers of nutrition,body condition,oxidative stress,and antioxidative responses during pre-breeding stage.Our results showed that urban ETSs displayed distinct glucolipid metabolism compared to rural ETSs,characterized by higher levels of free fatty acids,β-hydroxybutyric acid,high-density lipoprotein(HDL),and total cholesterol,alongside lower levels of triglycerides,glucose(Glu),and fat content(FC).No significant differences were observed in other physiological markers.Additionally,both sexes of urban ETSs exhibited similar profiles across these markers,unlike rural populations where females showed higher Glu and total protein levels and lower HDL and FC levels than males.Our findings suggest that birds adjust their nutritional physiological markers in response to urbanization,likely due to dietary differences between urban and rural environments.Furthermore,sex differences in physiological markers of nutrition,body condition,oxidative stress,and antioxidant responses appear to diminish in urban settings.展开更多
Avian embryos,which develop within eggs,exhibit remarkable tolerance to extremely low temperatures.Despite being a common trait among all birds,the mechanisms underlying this cold tolerance in avian embryos remain lar...Avian embryos,which develop within eggs,exhibit remarkable tolerance to extremely low temperatures.Despite being a common trait among all birds,the mechanisms underlying this cold tolerance in avian embryos remain largely unknown.To gain a better understanding of this phenomenon and the coping mechanisms involved,we reviewed the literature on severe cold tolerance in embryos of both wild and domestic birds.We found that embryos of different bird orders exhibit tolerance to severe cold during their development.In response to cold stress,embryos slow down their heartbeat rates and metabolism.In severe cold temperatures,embryos can suspend these processes,entering a torpid-like state of cardiac arrest.To compensate for these developmental delays,embryos extend their regular incubation periods.Depending on their embryonic age,embryos of all bird species can tolerate acute severe cold regimes;only a few tolerate chronic severe cold regimes.We also discussed various extrinsic and intrinsic factors that affect the tolerance of bird embryos to low temperatures before and after incubation.Cold tolerance appears to be a heritable trait shared by wild and domestic embryos of all bird classes,regardless of egg size or development(altricial/precocial).Driven by environmental variability,cold tolerance in avian embryos is an optimal physiological and ecological strategy to mitigate the adverse effects of cold conditions on their development in response to fluctuating environmental temperatures.展开更多
The hypothalamic-pituitary-gonadal(HPG)axis ubiquitously regulates seasonal reproduction,following the rhythmicity of a suite of environmental cues.Birds display prominent seasonal variations in gonad size regulated b...The hypothalamic-pituitary-gonadal(HPG)axis ubiquitously regulates seasonal reproduction,following the rhythmicity of a suite of environmental cues.Birds display prominent seasonal variations in gonad size regulated by two hypothalamic peptides,gonadotropin-releasing hormone-1(GnRH-I)and gonadotropin-inhibiting hormone(GnIH).How multi-brooded avian species adjust GnRH-I and GnIH to regulate gonadal morphology seasonally remains largely unknown.Here,we studied the variations in the hypothalamic immunoreactivity(ir)of GnRH-I and GnIH,gonadal proliferation,and apoptosis in a typical multi-brooded species,the Eurasian Tree Sparrow(Passer montanus),across the pre-breeding(PB),first breeding(FB),second breeding(SB),pre-basic molt(PM),and wintering stages(WS).Our results showed that both sexes had higher preoptic area(POA)-GnRH-I-ir but lower paraventricular nucleus(PVN)-GnIH-ir neurons during the breeding stages(FB and SB)relative to other life-history stages,with no significant differences between two broods.The testes and ovaries were significantly larger during the breeding stages.Testicular volume increased during the two broods due to anincreased diameter of seminiferous tubules.Furthermore,there were more testicular apoptotic cells in PB and WS stages than in breeding stages,and in PB stage than in PM stage.Males had higher POA-GnRH-I expression than females during the breeding stages,but both sexes had comparable PVN-GnIH expression throughout the annual cycle.Both sexes of the sparrows may undergo a similar pattern of life-history stage-dependent variation in the hypothalamic GnRH-I,GnIH,and gonadal morphology,except that during breeding stages,males may display higher expression of POA-GnRH-I relative to females.The higher expression of POA-GnRH-I-ir in breeding male sparrows may be critical for male-dependent parental care.展开更多
Hibernation is one of the fundamental strategies in response to cold environmental temperatures.During hibernation,the endocrine and circadian systems ensure minimal expenditure of energy for survival.The circadian rh...Hibernation is one of the fundamental strategies in response to cold environmental temperatures.During hibernation,the endocrine and circadian systems ensure minimal expenditure of energy for survival.The circadian rhythms of key hormones,melatonin(MT),corticosterone(CORT),triiodothyronine(T3),and thyroxine(T4),and the underlying molecular regulatory mechanisms of hibernation have been well determined in mammals but not in ectotherms.Here,a terrestrial hibernating species,Asiatic toad(Bufo gargarizans),was employed to investigate the plasma CORT,MT,T3,and T4;and the retina,brain,and liver mRNA expression of the core clock genes,including circadian locomotor output cycles kaput(Clock),brain and muscle ARNT-like 1(Bmal1),cryptochrome(Cry)1 and 2,and period(Per)1 and 2,at 7-time points over a 24-h period under acute cold(1 day at 4℃),and hibernation(45 days at 4℃).Our results showed that the circadian rhythms of the core clock genes were rather unaffected by acute cold exposure in the retina,unlike the brain and liver.In contrast,during hibernation,the liver clock genes displayed significant circadian oscillations,while those in the retina and brain stopped ticking.Furthermore,plasma CORT expressed circadian oscillations in both groups,and T3 in acute cold exposure group,whereas T4 and MT did not.Our results reveal that the plasma CORT and the liver sustain rhythmicity when the brain was not,indicating that the liver clock along with the adrenal clock synergistically maintains the metabolic requirements to ensure basic survival in hibernating Asiatic toads.展开更多
Human commensal species take advantage of anthropogenic conditions that are less likely to be challenged by the selective pressures of natural environments.Their morphological and physiological phenotypes can therefor...Human commensal species take advantage of anthropogenic conditions that are less likely to be challenged by the selective pressures of natural environments.Their morphological and physiological phenotypes can therefore dissociate from habitat characteristics.Understanding how these species adjust their morphological and physiological traits across latitudinal gradients is fundamental to uncovering the eco-physiological strategies underlying coping mechanisms.Here,we studied morphological traits in breeding Eurasian tree sparrows(ETSs;Passer montanus)among low-latitude(Yunnan and Hunan)and middle-latitude(Hebei)localities in China.We then compared body mass;lengths of bill,tarsometatarsus,wing,total body,and tail feather;and baseline and capture stress-induced levels of plasma corticosterone(CORT)and the metabolites including glucose(Glu),total triglyceride(TG),free fatty acid(FFA),total protein,and uric acid(UA).None of the measured morphological parameters varied with latitude except in the Hunan population,which demonstrated longer bills than those in other populations.Stress-induced CORT levels significantly exceeded baseline levels and decreased with increasing latitude,but total integrated CORT levels did not vary with latitude.Capture stress-induced significantly increased Glu levels and decreased TG levels,independent of site.However,the Hunan population had significantly higher baseline CORT,baseline and stress-induced FFA levels,but lower UA levels,which differed from other populations.Our results suggest that rather than morphological adjustments,physiological adjustments are mainly involved in coping mechanisms for middle-latitude adaptation in ETSs.It is worth investigating whether other avian species also exhibit such dissociation from external morphological designs while depending on physiological adjustments.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,31971413)to D.L.
文摘Numerous bird species have adapted to rapid urbanization,navigating challenges introduced by novel stressors.While prior research has explored how urban exploiters adjust their physiology relative to their rural counterparts during breeding season,the modulation of multiple physiological markers outside of reproduction,and the maintenance of sex-specific differences,remain less understood.Using an urban exploiter,the Eurasian tree sparrow(ETS;Passer montanus),we investigated how both sexes of urban and rural populations modulate twenty-two physiological markers of nutrition,body condition,oxidative stress,and antioxidative responses during pre-breeding stage.Our results showed that urban ETSs displayed distinct glucolipid metabolism compared to rural ETSs,characterized by higher levels of free fatty acids,β-hydroxybutyric acid,high-density lipoprotein(HDL),and total cholesterol,alongside lower levels of triglycerides,glucose(Glu),and fat content(FC).No significant differences were observed in other physiological markers.Additionally,both sexes of urban ETSs exhibited similar profiles across these markers,unlike rural populations where females showed higher Glu and total protein levels and lower HDL and FC levels than males.Our findings suggest that birds adjust their nutritional physiological markers in response to urbanization,likely due to dietary differences between urban and rural environments.Furthermore,sex differences in physiological markers of nutrition,body condition,oxidative stress,and antioxidant responses appear to diminish in urban settings.
基金supported by the National Natural Science Foundation of China(NSFC,31971413)granted to DLthe Second Tibetan Plateau Scientific Expedition and Research Program(STEP,2019QZKK0501)granted to DL。
文摘Avian embryos,which develop within eggs,exhibit remarkable tolerance to extremely low temperatures.Despite being a common trait among all birds,the mechanisms underlying this cold tolerance in avian embryos remain largely unknown.To gain a better understanding of this phenomenon and the coping mechanisms involved,we reviewed the literature on severe cold tolerance in embryos of both wild and domestic birds.We found that embryos of different bird orders exhibit tolerance to severe cold during their development.In response to cold stress,embryos slow down their heartbeat rates and metabolism.In severe cold temperatures,embryos can suspend these processes,entering a torpid-like state of cardiac arrest.To compensate for these developmental delays,embryos extend their regular incubation periods.Depending on their embryonic age,embryos of all bird species can tolerate acute severe cold regimes;only a few tolerate chronic severe cold regimes.We also discussed various extrinsic and intrinsic factors that affect the tolerance of bird embryos to low temperatures before and after incubation.Cold tolerance appears to be a heritable trait shared by wild and domestic embryos of all bird classes,regardless of egg size or development(altricial/precocial).Driven by environmental variability,cold tolerance in avian embryos is an optimal physiological and ecological strategy to mitigate the adverse effects of cold conditions on their development in response to fluctuating environmental temperatures.
基金supported by the National Natural Science Foundation of China(NSFC,31971413)to DL and NSFC(31770445)to YWthe Natural Science Foundation of Hebei Province,China(NSFHB,C2020205038)to DL and NSFHB(C2020205005)the Postdoctoral Research Foundation of China(PRFC,2020M670685)to LW。
文摘The hypothalamic-pituitary-gonadal(HPG)axis ubiquitously regulates seasonal reproduction,following the rhythmicity of a suite of environmental cues.Birds display prominent seasonal variations in gonad size regulated by two hypothalamic peptides,gonadotropin-releasing hormone-1(GnRH-I)and gonadotropin-inhibiting hormone(GnIH).How multi-brooded avian species adjust GnRH-I and GnIH to regulate gonadal morphology seasonally remains largely unknown.Here,we studied the variations in the hypothalamic immunoreactivity(ir)of GnRH-I and GnIH,gonadal proliferation,and apoptosis in a typical multi-brooded species,the Eurasian Tree Sparrow(Passer montanus),across the pre-breeding(PB),first breeding(FB),second breeding(SB),pre-basic molt(PM),and wintering stages(WS).Our results showed that both sexes had higher preoptic area(POA)-GnRH-I-ir but lower paraventricular nucleus(PVN)-GnIH-ir neurons during the breeding stages(FB and SB)relative to other life-history stages,with no significant differences between two broods.The testes and ovaries were significantly larger during the breeding stages.Testicular volume increased during the two broods due to anincreased diameter of seminiferous tubules.Furthermore,there were more testicular apoptotic cells in PB and WS stages than in breeding stages,and in PB stage than in PM stage.Males had higher POA-GnRH-I expression than females during the breeding stages,but both sexes had comparable PVN-GnIH expression throughout the annual cycle.Both sexes of the sparrows may undergo a similar pattern of life-history stage-dependent variation in the hypothalamic GnRH-I,GnIH,and gonadal morphology,except that during breeding stages,males may display higher expression of POA-GnRH-I relative to females.The higher expression of POA-GnRH-I-ir in breeding male sparrows may be critical for male-dependent parental care.
基金This work was supported by the National Natural Science Foundation of China(NSFC,31270457,30800129 to Z.X.),NSFC(31971413)the Natural Science Foundation of Hebei Province(NSFHB,C2020205038 to D.L).
文摘Hibernation is one of the fundamental strategies in response to cold environmental temperatures.During hibernation,the endocrine and circadian systems ensure minimal expenditure of energy for survival.The circadian rhythms of key hormones,melatonin(MT),corticosterone(CORT),triiodothyronine(T3),and thyroxine(T4),and the underlying molecular regulatory mechanisms of hibernation have been well determined in mammals but not in ectotherms.Here,a terrestrial hibernating species,Asiatic toad(Bufo gargarizans),was employed to investigate the plasma CORT,MT,T3,and T4;and the retina,brain,and liver mRNA expression of the core clock genes,including circadian locomotor output cycles kaput(Clock),brain and muscle ARNT-like 1(Bmal1),cryptochrome(Cry)1 and 2,and period(Per)1 and 2,at 7-time points over a 24-h period under acute cold(1 day at 4℃),and hibernation(45 days at 4℃).Our results showed that the circadian rhythms of the core clock genes were rather unaffected by acute cold exposure in the retina,unlike the brain and liver.In contrast,during hibernation,the liver clock genes displayed significant circadian oscillations,while those in the retina and brain stopped ticking.Furthermore,plasma CORT expressed circadian oscillations in both groups,and T3 in acute cold exposure group,whereas T4 and MT did not.Our results reveal that the plasma CORT and the liver sustain rhythmicity when the brain was not,indicating that the liver clock along with the adrenal clock synergistically maintains the metabolic requirements to ensure basic survival in hibernating Asiatic toads.
基金We thank Yinchao Hao and Wande Li for their assistance with sample collection.This study was funded by the National Natural Science Foundation of China(NSFC,31971413)Natural Science Foundation of Hebei Province(NSFHP,C2020205038)to D.L.Science and Technology Project of Hebei Education Department(QN2019103)to Y.S.
文摘Human commensal species take advantage of anthropogenic conditions that are less likely to be challenged by the selective pressures of natural environments.Their morphological and physiological phenotypes can therefore dissociate from habitat characteristics.Understanding how these species adjust their morphological and physiological traits across latitudinal gradients is fundamental to uncovering the eco-physiological strategies underlying coping mechanisms.Here,we studied morphological traits in breeding Eurasian tree sparrows(ETSs;Passer montanus)among low-latitude(Yunnan and Hunan)and middle-latitude(Hebei)localities in China.We then compared body mass;lengths of bill,tarsometatarsus,wing,total body,and tail feather;and baseline and capture stress-induced levels of plasma corticosterone(CORT)and the metabolites including glucose(Glu),total triglyceride(TG),free fatty acid(FFA),total protein,and uric acid(UA).None of the measured morphological parameters varied with latitude except in the Hunan population,which demonstrated longer bills than those in other populations.Stress-induced CORT levels significantly exceeded baseline levels and decreased with increasing latitude,but total integrated CORT levels did not vary with latitude.Capture stress-induced significantly increased Glu levels and decreased TG levels,independent of site.However,the Hunan population had significantly higher baseline CORT,baseline and stress-induced FFA levels,but lower UA levels,which differed from other populations.Our results suggest that rather than morphological adjustments,physiological adjustments are mainly involved in coping mechanisms for middle-latitude adaptation in ETSs.It is worth investigating whether other avian species also exhibit such dissociation from external morphological designs while depending on physiological adjustments.
