When an immobile prey has detected an immobile predator nearby, predation risk is greater when the predator is closer. Consequently, prey flee with shorter latency as standing distance （predator-prey distance when bo...When an immobile prey has detected an immobile predator nearby, predation risk is greater when the predator is closer. Consequently, prey flee with shorter latency as standing distance （predator-prey distance when both are still） decreases. Since it was first reported in 2009, this relationship has been confirmed in the few species studied. However, little is known about the functional relationship between standing distance and latency to flee （LF）. We hypothesized that LF increases as standing distance increases at short distances, but reaches a plateau at longer distances where prey can escape reliably if attacked. We simulated immobile predators by moving slowly into positions near striped plateau lizards Sceloporus virgatus, stopping and then remaining immobile, and recording LF from the stopping time. LF increased from shorter to longer standing distances in a decelerating manner. The relationship was concave downward, and LF was indistinguishable among the longer standing distance groups. Latency to flee appears to reach a plateau or approach an asymptotic value as stand- ing distance increases. The effect size of standing distance was large, indicating that S. virgatus sensi- tively adjusts LF to the level of risk associated with standing distance. Relationships between risk assessment and theoretical zones associated with risk, its assessment by prey, and escape decisions are discussed. Effect sizes of standing distance were substantial to large in all studies to date, indicating that standing distance is an important predation risk factor when both predator and prey are immobile.展开更多
Intensive labor chores for broiler production could be reduced by using automated systems.However,broilers’response toward automated systems remains unclear.The experiments were conducted to determine the avoidance d...Intensive labor chores for broiler production could be reduced by using automated systems.However,broilers’response toward automated systems remains unclear.The experiments were conducted to determine the avoidance distance(AD)and the fleeing speed(FS)of 4-8 weeks old broilers toward two aerial systems,a rail with a dummy arm and a drone,operated at different speeds(0.2-1.2 m/s),and heights(0.3-1.8 m)in a commercial broiler house.The broiler AD to a human assessor was also determined for comparison.Results show that the overall mean and standard error(SE)of broiler AD were 63±3 cm for the assessor,58±1 cm for the rail,and 85±1 cm for the drone.As bird age increased from week 4 to week 8,broiler AD reduced significantly from 82 to 45 cm for the rail but showed no significant change for the drone.As the operational speed increased,broiler AD significantly increased from 54 cm(0.2 m/s)to 62 cm(0.4 m/s)for the rail,and from 81 cm(0.4 m/s)to 89 cm(1.2 m/s)for the drone.As the operational height increased,broiler AD increased from 54 cm(0.3 m)to 57 cm(1.5 m)for the rail and 81 cm(1.2 m)to 88 cm(1.8 m)for the drone.Overall mean and SE of broiler FS were 0.21±0.01 m/s for the rail and 0.65±0.01 m/s for the drone.As bird age increased from week 4 to week 8,the mean broiler FS decreased from 0.47 to 0.07 m/s for the rail and from 0.84 to 0.16 m/s for the drone.Increasing operational speed from 0.2 to 0.4 m/s for the rail and from 0.4 to 1.2 m/s for the drone significantly increased the mean FS from 0.18 to 0.24 m/s and from 0.52 to 0.78 m/s,respectively.Increasing the height of the rail from 0.3 to 1.5 m decreased the broiler FS from 0.27 to 0.16 m/s.However,increasing drone height from 1.2 to 1.8 m retained a similar FS.The outcomes of this study can help to better understand the interaction of broilers with aerial systems and provide insights into the optimization of robotic operational strategies while maintaining good broiler welfare production.展开更多
[ Objective ] The paper was to study the density restriction effects of reproductive rate of rice brown planthopper （BPH） population in super indiea and japonica hybrid rice Yongyou 6. [Method] Different amounts of ...[ Objective ] The paper was to study the density restriction effects of reproductive rate of rice brown planthopper （BPH） population in super indiea and japonica hybrid rice Yongyou 6. [Method] Different amounts of rice brown planthoppor were released to super indiea and japonica hybrid flee Yongyou 6 during fillering, booting and gain filling stage, respectively. The reproductive rate and variation dynamics of rice brown planthoppor in super rice was also investigated and analyzed. [Result] Tillering stage： the population quantity of rice brown planthoppor during booting and gain filling stage gradually increased with the increasing basal amount of its population during tillering stage; when the population density of rice brown planthopper during grain filling stage reached a certain limit （ 〉 250 head/cluster）, the population density during milking stage showed decrease trend with the increasing of such density; the development of rice brown planthoppor population in super rice Yongyou 6 showed the characteristics of fast in middle and slow in two ends. Booting stage： the development of rice brown planthopper pop- ulation from booting to gain filling stage increased with the increasing basal amount of density, and their correlation during milking stage was not significant; flee brown planthopper population still had high reproduction capacity in the middle and late stage of super rice, which had latent risk on rice yield. Gain filling stage ： when population density of rice brown planthopper 〈 70 head/cluster, the development of it population increased with the increase of basal amount of density, which had great threat to yield. [ Conclusion] The result provided theoretical basis for establishment and improvement of monitoring early warning system, cost-ef- fective control of occurrence and damage of rice brown planthopper, and improvement of the sustained control ability against rice brown planthopper.展开更多
Chitinases （EC3.2.1.14）, found in a wide range of organisms, catalyze the hydrolysis of chitin and play a major role in defense mechanisms against fungal pathogens. The alignment and typical domains were analyzed us...Chitinases （EC3.2.1.14）, found in a wide range of organisms, catalyze the hydrolysis of chitin and play a major role in defense mechanisms against fungal pathogens. The alignment and typical domains were analyzed using basic local alignment search tool （BLAST） and simple modular architecture research tool （SMART）, respectively. On the basis of the annotations of flee （Oryza sativa L.） and Arabidopsis genomic sequences and using the bio-software SignalP3.0, TMHMM2.0, TargetPl.1, and big-Pi Predictor, 25 out of 37 and 16 out of 24 open reading frames （ORFs） with chitinase activity from rice and Arabidopsis, respectively, were predicted to have signal pepfides （SPs）, which have an average of 24.8 amino acids at the N-terminal region. Some of the chitinases were secreted extracellularly, whereas some were located in the vacuole. The phylogenic relationship was analyzed with 61 ORFs and 25 known ehitinases and they were classified into 6 clusters using Clustal X and MEGA3.1. This classification is not completely consistent when compared with the traditional system that classifies the chitinases into 7 classes. The frequency of distribution of amino acid residues was distinct in different clusters. The contents of alanine, glycine, serine, and leucine were very high in each cluster, whereas the contents of methionine, histidine, tryptophan, and cysteine were lower than 20%. Each cluster had distinct amino acid characteristics. Alanine, valine, leucine, cysteine, serine, and lysine were rich in Clusters Ⅰ to Ⅵ, respectively.展开更多
Fluctuating snow-covered elevation （FSCE） was conceptualized and proposed to characterize within-year variation of the border between snow-covered and snow-free area in mountainous regions. Two parameters, namely me...Fluctuating snow-covered elevation （FSCE） was conceptualized and proposed to characterize within-year variation of the border between snow-covered and snow-free area in mountainous regions. Two parameters, namely median of snow flee period （Tm） and snow free duration （AT）, were defined to quantify FSCE. A regression model of FSCE was developed for the Lhasa River Basin, Niyang River Basin, and Changdu region in eastern Tibet. Statistical analysis of the snow-products data with a spatial resolution of 25km×25km shows that： （1） Tm correlates weakly with geographical and topographic factors, having the yearly mean value of July 31; （2） △T correlates significantly with the average elevation of the snow-products cell, having the yearly mean value of nearly five months （i.e., 151 days）; （3） the region begins snow disappearance in late April and finishes snow coverage in mid November, being snow-free from late June to mid September and snow-covered from December to March in the next year. In addi- tion, snow-products with higher spatial resolution will be helpful to characterize FSCE in smaller spatial scales.展开更多
文摘When an immobile prey has detected an immobile predator nearby, predation risk is greater when the predator is closer. Consequently, prey flee with shorter latency as standing distance （predator-prey distance when both are still） decreases. Since it was first reported in 2009, this relationship has been confirmed in the few species studied. However, little is known about the functional relationship between standing distance and latency to flee （LF）. We hypothesized that LF increases as standing distance increases at short distances, but reaches a plateau at longer distances where prey can escape reliably if attacked. We simulated immobile predators by moving slowly into positions near striped plateau lizards Sceloporus virgatus, stopping and then remaining immobile, and recording LF from the stopping time. LF increased from shorter to longer standing distances in a decelerating manner. The relationship was concave downward, and LF was indistinguishable among the longer standing distance groups. Latency to flee appears to reach a plateau or approach an asymptotic value as stand- ing distance increases. The effect size of standing distance was large, indicating that S. virgatus sensi- tively adjusts LF to the level of risk associated with standing distance. Relationships between risk assessment and theoretical zones associated with risk, its assessment by prey, and escape decisions are discussed. Effect sizes of standing distance were substantial to large in all studies to date, indicating that standing distance is an important predation risk factor when both predator and prey are immobile.
文摘Intensive labor chores for broiler production could be reduced by using automated systems.However,broilers’response toward automated systems remains unclear.The experiments were conducted to determine the avoidance distance(AD)and the fleeing speed(FS)of 4-8 weeks old broilers toward two aerial systems,a rail with a dummy arm and a drone,operated at different speeds(0.2-1.2 m/s),and heights(0.3-1.8 m)in a commercial broiler house.The broiler AD to a human assessor was also determined for comparison.Results show that the overall mean and standard error(SE)of broiler AD were 63±3 cm for the assessor,58±1 cm for the rail,and 85±1 cm for the drone.As bird age increased from week 4 to week 8,broiler AD reduced significantly from 82 to 45 cm for the rail but showed no significant change for the drone.As the operational speed increased,broiler AD significantly increased from 54 cm(0.2 m/s)to 62 cm(0.4 m/s)for the rail,and from 81 cm(0.4 m/s)to 89 cm(1.2 m/s)for the drone.As the operational height increased,broiler AD increased from 54 cm(0.3 m)to 57 cm(1.5 m)for the rail and 81 cm(1.2 m)to 88 cm(1.8 m)for the drone.Overall mean and SE of broiler FS were 0.21±0.01 m/s for the rail and 0.65±0.01 m/s for the drone.As bird age increased from week 4 to week 8,the mean broiler FS decreased from 0.47 to 0.07 m/s for the rail and from 0.84 to 0.16 m/s for the drone.Increasing operational speed from 0.2 to 0.4 m/s for the rail and from 0.4 to 1.2 m/s for the drone significantly increased the mean FS from 0.18 to 0.24 m/s and from 0.52 to 0.78 m/s,respectively.Increasing the height of the rail from 0.3 to 1.5 m decreased the broiler FS from 0.27 to 0.16 m/s.However,increasing drone height from 1.2 to 1.8 m retained a similar FS.The outcomes of this study can help to better understand the interaction of broilers with aerial systems and provide insights into the optimization of robotic operational strategies while maintaining good broiler welfare production.
文摘[ Objective ] The paper was to study the density restriction effects of reproductive rate of rice brown planthopper （BPH） population in super indiea and japonica hybrid rice Yongyou 6. [Method] Different amounts of rice brown planthoppor were released to super indiea and japonica hybrid flee Yongyou 6 during fillering, booting and gain filling stage, respectively. The reproductive rate and variation dynamics of rice brown planthoppor in super rice was also investigated and analyzed. [Result] Tillering stage： the population quantity of rice brown planthoppor during booting and gain filling stage gradually increased with the increasing basal amount of its population during tillering stage; when the population density of rice brown planthopper during grain filling stage reached a certain limit （ 〉 250 head/cluster）, the population density during milking stage showed decrease trend with the increasing of such density; the development of rice brown planthoppor population in super rice Yongyou 6 showed the characteristics of fast in middle and slow in two ends. Booting stage： the development of rice brown planthopper pop- ulation from booting to gain filling stage increased with the increasing basal amount of density, and their correlation during milking stage was not significant; flee brown planthopper population still had high reproduction capacity in the middle and late stage of super rice, which had latent risk on rice yield. Gain filling stage ： when population density of rice brown planthopper 〈 70 head/cluster, the development of it population increased with the increase of basal amount of density, which had great threat to yield. [ Conclusion] The result provided theoretical basis for establishment and improvement of monitoring early warning system, cost-ef- fective control of occurrence and damage of rice brown planthopper, and improvement of the sustained control ability against rice brown planthopper.
基金This work was supported by the 863 Program (No. 2002AA245041), the National Natural Science Foundation of China (No. 30260006), and the R&D Foundation of Yunnan Province (No. 2003GP06).
文摘Chitinases （EC3.2.1.14）, found in a wide range of organisms, catalyze the hydrolysis of chitin and play a major role in defense mechanisms against fungal pathogens. The alignment and typical domains were analyzed using basic local alignment search tool （BLAST） and simple modular architecture research tool （SMART）, respectively. On the basis of the annotations of flee （Oryza sativa L.） and Arabidopsis genomic sequences and using the bio-software SignalP3.0, TMHMM2.0, TargetPl.1, and big-Pi Predictor, 25 out of 37 and 16 out of 24 open reading frames （ORFs） with chitinase activity from rice and Arabidopsis, respectively, were predicted to have signal pepfides （SPs）, which have an average of 24.8 amino acids at the N-terminal region. Some of the chitinases were secreted extracellularly, whereas some were located in the vacuole. The phylogenic relationship was analyzed with 61 ORFs and 25 known ehitinases and they were classified into 6 clusters using Clustal X and MEGA3.1. This classification is not completely consistent when compared with the traditional system that classifies the chitinases into 7 classes. The frequency of distribution of amino acid residues was distinct in different clusters. The contents of alanine, glycine, serine, and leucine were very high in each cluster, whereas the contents of methionine, histidine, tryptophan, and cysteine were lower than 20%. Each cluster had distinct amino acid characteristics. Alanine, valine, leucine, cysteine, serine, and lysine were rich in Clusters Ⅰ to Ⅵ, respectively.
基金supported by the National Natural Science Foundation of China under Grant No.50221903by the Ministry of Science and Technology of China under Grant No.2007BAC06B06
文摘Fluctuating snow-covered elevation （FSCE） was conceptualized and proposed to characterize within-year variation of the border between snow-covered and snow-free area in mountainous regions. Two parameters, namely median of snow flee period （Tm） and snow free duration （AT）, were defined to quantify FSCE. A regression model of FSCE was developed for the Lhasa River Basin, Niyang River Basin, and Changdu region in eastern Tibet. Statistical analysis of the snow-products data with a spatial resolution of 25km×25km shows that： （1） Tm correlates weakly with geographical and topographic factors, having the yearly mean value of July 31; （2） △T correlates significantly with the average elevation of the snow-products cell, having the yearly mean value of nearly five months （i.e., 151 days）; （3） the region begins snow disappearance in late April and finishes snow coverage in mid November, being snow-free from late June to mid September and snow-covered from December to March in the next year. In addi- tion, snow-products with higher spatial resolution will be helpful to characterize FSCE in smaller spatial scales.
