Background: Sexual size dimorphism(SSD) occurs in a wide range of species in birds and other animals, but the magnitude of SSD often varies with environmental conditions. In general, in the developmental stages, the l...Background: Sexual size dimorphism(SSD) occurs in a wide range of species in birds and other animals, but the magnitude of SSD often varies with environmental conditions. In general, in the developmental stages, the larger sex is more vulnerable to adverse environmental conditions because the larger sex requires more energy than the smaller sex. However, this may not hold true for birds with large brood sizes; the larger sex can acquire more food by suppressing the smaller sex. In addition, most previous studies have been experimental, such as by manipulating clutch size and ectoparasites, which may not reflect natural conditions.Methods: In the present study, we propose a general framework to assess sexual differences in environmental sensitivity in natural populations. Because environmental conditions change throughout the breeding season, seasonal changes of nestling SSD and sex ratio should reflect sexual differences in environmental sensitivity. We applied this approach to a large dataset(1555 nestlings over 5 years) of Japanese Tits(Parus minor). In this population, the male nestling is generally larger than the female(5% SSD in body weight).Results: We found that the magnitude of SSD(weight, tarsus, wing) and fledgling sex ratio increased both in the beginning and the end of the breeding season.Conclusion: Our study suggested that female nestlings are more valuable to poor environmental conditions in the relatively fecund species. This study underscores the importance of brood size on sexual differences in environmental stochasticity and our framework encourages comparative analysis among different bird species.展开更多
In order to analyze the characteristics of surface water resource quality for the reconstruction of old water treatment plant,multivariate statistical techniques such as cluster analysis and factor analysis were appli...In order to analyze the characteristics of surface water resource quality for the reconstruction of old water treatment plant,multivariate statistical techniques such as cluster analysis and factor analysis were applied to the data of Yuqiao Reservoir-surface water resource of the Luan River,China.The results of cluster analysis demonstrate that the months of one year were divided into 3 groups and the characteristic of clusters was agreed with the seasonal characteristics in North China.Three factors were derived from the complicated set using factor analysis.Factor 1 included turbidity and chlorophyll,which seemed to be related to the anthropogenic activities;factor 2 included alkaline and hardness,which were related to the natural characteristic of surface water;and factor 3 included Cl and NO2-N affected by mineral and agricultural activities.The sinusoidal shape of the score plots of the three factors shows that the temporal variations caused by natural and human factors are linked to seasonality.展开更多
文摘Background: Sexual size dimorphism(SSD) occurs in a wide range of species in birds and other animals, but the magnitude of SSD often varies with environmental conditions. In general, in the developmental stages, the larger sex is more vulnerable to adverse environmental conditions because the larger sex requires more energy than the smaller sex. However, this may not hold true for birds with large brood sizes; the larger sex can acquire more food by suppressing the smaller sex. In addition, most previous studies have been experimental, such as by manipulating clutch size and ectoparasites, which may not reflect natural conditions.Methods: In the present study, we propose a general framework to assess sexual differences in environmental sensitivity in natural populations. Because environmental conditions change throughout the breeding season, seasonal changes of nestling SSD and sex ratio should reflect sexual differences in environmental sensitivity. We applied this approach to a large dataset(1555 nestlings over 5 years) of Japanese Tits(Parus minor). In this population, the male nestling is generally larger than the female(5% SSD in body weight).Results: We found that the magnitude of SSD(weight, tarsus, wing) and fledgling sex ratio increased both in the beginning and the end of the breeding season.Conclusion: Our study suggested that female nestlings are more valuable to poor environmental conditions in the relatively fecund species. This study underscores the importance of brood size on sexual differences in environmental stochasticity and our framework encourages comparative analysis among different bird species.
基金Project supported by the Hi-Tech Research and Development(863)Program of China(No.2006AA06Z311)Development Program for Outstanding Young Teachers in Harbin Institute of Technology(No.HITQNJS.2008.044),China
文摘In order to analyze the characteristics of surface water resource quality for the reconstruction of old water treatment plant,multivariate statistical techniques such as cluster analysis and factor analysis were applied to the data of Yuqiao Reservoir-surface water resource of the Luan River,China.The results of cluster analysis demonstrate that the months of one year were divided into 3 groups and the characteristic of clusters was agreed with the seasonal characteristics in North China.Three factors were derived from the complicated set using factor analysis.Factor 1 included turbidity and chlorophyll,which seemed to be related to the anthropogenic activities;factor 2 included alkaline and hardness,which were related to the natural characteristic of surface water;and factor 3 included Cl and NO2-N affected by mineral and agricultural activities.The sinusoidal shape of the score plots of the three factors shows that the temporal variations caused by natural and human factors are linked to seasonality.
