Sibling cannibalism is relatively common in nature,but its evolution in birds and certain other vertebrates with extended parental care had been discarded.Here,however,we demonstrate its regular occurrence in two Euro...Sibling cannibalism is relatively common in nature,but its evolution in birds and certain other vertebrates with extended parental care had been discarded.Here,however,we demonstrate its regular occurrence in two European populations of the Eurasian hoopoe(Upupa epops)and explore possible adaptive and non-adaptive explanations.Results showed that sibling cannibalism was more frequently detected in Spain(51.7%)than in Austria(5.9%).In these two populations,the hoopoes laid similar clutch sizes,resulting in similar fledging production,but hatching failures were more frequent in the northern population.Consequently,having more nestlings condemned to die in the southern population may explain the higher incidence of sibling cannibalism.In accordance with this interpretation,hatching span and failure,but not breeding date,explained the probability of sibling cannibalism in the Spanish hoopoes,while all three variables predicted brood reduction intensity.Furthermore,experimental food supply reduced the probability of sibling cannibalism,but not the intensity of brood reduction.Finally,females allocated fewer resources to the smallest nestlings when they were going to starve,but not necessarily when they were going to be used as food for their siblings.These results suggest that hoopoes produce extra eggs that,in the case of reduced hatching failure and food scarcity,produce nestlings that are used to feed older siblings.These findings provide the first evidence that sibling cannibalism occurs regularly in a bird species,thus expanding our evolutionary understanding of clutch size,hatching asynchrony,parent-offspring conflict,infanticide,and sibling cannibalism in the animal kingdom.展开更多
Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncer...Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncertain.Beyond timing,procedural choices in PGT-A must balance diagnostic yield against potential harm from additional handling(e.g.,repeat TE biopsy or cryopreservation steps),as underscored by a recent systematic review and meta-analysis[1].展开更多
一、完形填空When my children were young,I used to read to them every evening before bed.One of their favorite stories was called Somebody Loves You,Mr.Hatch.Mr.Hatch lived a_1_life.
Salinity is recognized as a pivotal factor limiting the migration of freshwater fish to brackish environments.The largemouth bass(LMB,Micropterus salmoides),a globally translocated freshwater fish,exhibits estuarine d...Salinity is recognized as a pivotal factor limiting the migration of freshwater fish to brackish environments.The largemouth bass(LMB,Micropterus salmoides),a globally translocated freshwater fish,exhibits estuarine distribution,yet its hyperosmoregulatory capacity during early ontogenetic stages remains inadequately understood.To investigate the impact of freshwater salinization,a series of experiments were conducted in Guangzhou and Foshan,China.Results reveal that freshwater-activated mature eggs and naturally fertilized oocytes maintained nearly identical osmotic homeostasis,with diameters of 1.38±0.07 mm and 1.37±0.05 mm,respectively.Furthermore,both exhibited peak water excretion at a salinity of 15.0.Remarkably,a reduction in water permeability was observed in hyperosmotic environments.Spontaneous hatching rates increased from 27.5%±14.4%in the 1.0 group to 75.1%±12.0%in the 6.0 group under fluctuating temperature conditions.Yolk-sac LMB larvae consistently reduced survival time from 12.5 d at 1.0 to 50.7±2.1 min at salinity of 35.0.Similarly,more developed larvae also experienced a decrease in survival time.Logistic regression models fitting lethal time with salinity indicated a sharp decrease between 10.0 and 20.0.These findings offer practical insights for predicting distribution patterns and enhancing aquaculture technology for LMB.Moreover,they may contribute theoretically to the broader understanding of the osmoregulatory mechanisms of freshwater fish.展开更多
星间精密测距是导航星座实现自主导航的核心技术。针对导航星座中码测量值精度低但无整周模糊度,载波相位测量值精度高但存在整周模糊度的特点,该文根据贝叶斯递推原理提出了一种衰减记忆高斯和滤波(Fading Memory Gaussian Sum Filter,...星间精密测距是导航星座实现自主导航的核心技术。针对导航星座中码测量值精度低但无整周模糊度,载波相位测量值精度高但存在整周模糊度的特点,该文根据贝叶斯递推原理提出了一种衰减记忆高斯和滤波(Fading Memory Gaussian Sum Filter,FMGSF)的伪距估计方法。该方法用高斯和形式近似表示系统后验概率密度,并根据卡尔曼滤波原理来更新高斯项的均值和方差,同时引入衰减记忆因子克服由于模型失配导致的滤波结果发散问题,利用重采样解决由于载波相位测量值不确定导致的算法复杂度增加问题。理论分析和仿真结果表明,该文提出的方法不仅能够克服周跳对伪距估计的影响,而且可以获得更好的测距精度。展开更多
基金supported by the Spanish Ministerio de CienciaInnovación y Universidades and European(FEDER)Funds(CGL2017-83103-P)。
文摘Sibling cannibalism is relatively common in nature,but its evolution in birds and certain other vertebrates with extended parental care had been discarded.Here,however,we demonstrate its regular occurrence in two European populations of the Eurasian hoopoe(Upupa epops)and explore possible adaptive and non-adaptive explanations.Results showed that sibling cannibalism was more frequently detected in Spain(51.7%)than in Austria(5.9%).In these two populations,the hoopoes laid similar clutch sizes,resulting in similar fledging production,but hatching failures were more frequent in the northern population.Consequently,having more nestlings condemned to die in the southern population may explain the higher incidence of sibling cannibalism.In accordance with this interpretation,hatching span and failure,but not breeding date,explained the probability of sibling cannibalism in the Spanish hoopoes,while all three variables predicted brood reduction intensity.Furthermore,experimental food supply reduced the probability of sibling cannibalism,but not the intensity of brood reduction.Finally,females allocated fewer resources to the smallest nestlings when they were going to starve,but not necessarily when they were going to be used as food for their siblings.These results suggest that hoopoes produce extra eggs that,in the case of reduced hatching failure and food scarcity,produce nestlings that are used to feed older siblings.These findings provide the first evidence that sibling cannibalism occurs regularly in a bird species,thus expanding our evolutionary understanding of clutch size,hatching asynchrony,parent-offspring conflict,infanticide,and sibling cannibalism in the animal kingdom.
文摘Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncertain.Beyond timing,procedural choices in PGT-A must balance diagnostic yield against potential harm from additional handling(e.g.,repeat TE biopsy or cryopreservation steps),as underscored by a recent systematic review and meta-analysis[1].
文摘一、完形填空When my children were young,I used to read to them every evening before bed.One of their favorite stories was called Somebody Loves You,Mr.Hatch.Mr.Hatch lived a_1_life.
基金the Natural Science Foundation of Guangdong Province(No.2016A030313145)the National Key R&D Program of China(No.2018YFD0900901)the Central Public-interest Scientific Institution Basal Research Fund,Chinese Academy of Fishery Sciences(No.2024SJRC9)。
文摘Salinity is recognized as a pivotal factor limiting the migration of freshwater fish to brackish environments.The largemouth bass(LMB,Micropterus salmoides),a globally translocated freshwater fish,exhibits estuarine distribution,yet its hyperosmoregulatory capacity during early ontogenetic stages remains inadequately understood.To investigate the impact of freshwater salinization,a series of experiments were conducted in Guangzhou and Foshan,China.Results reveal that freshwater-activated mature eggs and naturally fertilized oocytes maintained nearly identical osmotic homeostasis,with diameters of 1.38±0.07 mm and 1.37±0.05 mm,respectively.Furthermore,both exhibited peak water excretion at a salinity of 15.0.Remarkably,a reduction in water permeability was observed in hyperosmotic environments.Spontaneous hatching rates increased from 27.5%±14.4%in the 1.0 group to 75.1%±12.0%in the 6.0 group under fluctuating temperature conditions.Yolk-sac LMB larvae consistently reduced survival time from 12.5 d at 1.0 to 50.7±2.1 min at salinity of 35.0.Similarly,more developed larvae also experienced a decrease in survival time.Logistic regression models fitting lethal time with salinity indicated a sharp decrease between 10.0 and 20.0.These findings offer practical insights for predicting distribution patterns and enhancing aquaculture technology for LMB.Moreover,they may contribute theoretically to the broader understanding of the osmoregulatory mechanisms of freshwater fish.
文摘星间精密测距是导航星座实现自主导航的核心技术。针对导航星座中码测量值精度低但无整周模糊度,载波相位测量值精度高但存在整周模糊度的特点,该文根据贝叶斯递推原理提出了一种衰减记忆高斯和滤波(Fading Memory Gaussian Sum Filter,FMGSF)的伪距估计方法。该方法用高斯和形式近似表示系统后验概率密度,并根据卡尔曼滤波原理来更新高斯项的均值和方差,同时引入衰减记忆因子克服由于模型失配导致的滤波结果发散问题,利用重采样解决由于载波相位测量值不确定导致的算法复杂度增加问题。理论分析和仿真结果表明,该文提出的方法不仅能够克服周跳对伪距估计的影响,而且可以获得更好的测距精度。
