The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impa...The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impacted distributions and characteristics of dominant plant communities. However, besides groundwater depth, the community composition and species diversity were also influenced by physiognomy of the habitat. Based on the similarity coefficient, the differences between dominant plant communities were significant at different groundwater depths. Compared with other results relating to desert vegetation and groundwater depth, variations of community distribution were similar at the large spatial scale. However, in this extremely arid region, there were significant differences in community type and community succession when compared with other arid regions, especially in relationship to deep groundwater depth. With groundwater depth from deep to shallow, communities transformed with the sequence of Alhagi communities, Tamarix spp. communities, Populus communities, Phragmites communities, and Sophora communities. At groundwater depth of less than 6.0 m, the community type and composition changed, and the species diversity increased. Among these dominant species, Tamarix exhibited the biggest efficiency in resource utilization according to niche breadth, which means it possessed the best adaptability to environmental conditions at the oasis margins.展开更多
Aims Although the niche concept is of prime importance in ecology,the quantification of plant species’niches remains difficult.Here we propose that plant functional traits,as determinants of species performance,may b...Aims Although the niche concept is of prime importance in ecology,the quantification of plant species’niches remains difficult.Here we propose that plant functional traits,as determinants of species performance,may be useful tools for quantifying species niche parameters over environmental gradients.Important findings Under this framework,the mean trait values of a species determine its niche position along gradients,and intraspecific trait variability determines its niche breadth.This trait-based approach can provide an operational assessment of niche for a potentially large number of species,making it possible to understand and predict species niche shifts under environmental changes.We further advocate a promising method that recently appeared in the literature,which partitions trait diversity into among-and within-community components as a way to quantify the species niche in units of traits instead of environmental parameters.This approach allows the switch of the focus from ecological niches to trait niches,facilitating the examination of species coexistence along undefined environmental gradients.Altogether,the trait-based approach provides a promising toolkit for quantifying the species ecological niche and for understanding the evolution of species niche and traits.展开更多
This study aims to verify the concept of niches at multiple spatial scales in plant communities.To this end,we analyzed the niche characteristic of Rhododendron dauricum plant communities in Northeast China at three s...This study aims to verify the concept of niches at multiple spatial scales in plant communities.To this end,we analyzed the niche characteristic of Rhododendron dauricum plant communities in Northeast China at three spatial scales.At the local scale,we calculated the Importance Value(IV)of species in five communities in the north of the Da Hinggan Mountains.At the intermediate scale,we examined five communities in their entirety,calculated the niche breadth of the species,and integrated niche overlap and interspecific association to analyze interspecific relationships.Further,the generalized additive model(GAM)was used to analyze the impact of topography and soil factors on niche characteristics.At the regional scale,we analyzed the geographical distribution of dominant species of R.dauricum plant communities in Northeast China and used principal component analysis(PCA)to analyze the impact of geographical and climate factors on species distribution.The results show that at the local scale,the IV of the species in each community varies widely.At the intermediate scale,species with a wide niche breadth tend to have a high value for IV.Larix gmelinii,Betula platyphylla,R.dauricum,Ledum palustre,and Vaccinium vitis-idaea had a relatively wide niche breadth and a high niche overlap,and the interspecific associations were almost all positive.Elevation and soil nutrients were the most dominant environmental factors.At the regional scale,species with a wide niche breadth tend to have a wide range of distribution,and temperature and precipitation were the most dominant environmental factors.This study suggests that the niche characteristics at three scales are both related and different.Niche characteristics at the local scale were various and labile,and niche characteristics at the intermediate and regional scales were relatively regular.These results show some degree of consistency with previous studies from an evolutionary perspective.The action mechanisms of these communities are related to differences in the dominan展开更多
Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then t...Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then the co-relationship between genus species of soil dematiaceous hyphomycetes and ecosystem-types was analyzed. The results show that the amount and species distribution of soil dematiaceous hyphomycetes had an obvious variability in different ecosystem-types, and that the dominant genus species varied in the eight ecosystem-types studied, with Cladosporium being the dominant genus in seven of the eight ecosystem-types except wetland. The index of species diversity varied in different ecosystem-types. The niche breadth analysis showed that Cladosporium had the highest niche breadth and distributed in all ecosystem-types, while the genera with a narrow niche breadth distributed only in a few ecosystem-types. The results of niche overlap index analysis indicated that Stachybotrys and Torula, Doratomyces and Scolecobasidium, Cladosporium and Chrysosporium had a higher niche overlap, whereas Arthrinium and Gliomastix, Phialophora and Doratomyces, Oidiodendron and Ulocladium had no niche overlap.展开更多
Background: In forensic science the identification of a human is based on three important factors: Age, Sex and Stature. Bones are an important tool for it and among human bones the pelvis and the skull are the most r...Background: In forensic science the identification of a human is based on three important factors: Age, Sex and Stature. Bones are an important tool for it and among human bones the pelvis and the skull are the most reliable source for sex determination. In the absence of complete pelvis, mandi-ble becomes the important source for sex determination since mandible is the most durable and movable part of skull that can resist postmortem changes. The present study is conducted to assess the accuracy and role of few metric and morphological parameters in determination of the sex of dry adult human mandible of North Indian origin. Material & Methods: The Study is conducted on 50 dry intact human adult mandibles of North Indian origin. The metric parameters i.e. bigonial breadth, bicondylar breadth are measured with a Vernier Calliper by two observers. Non-metric parameters being observed are the morphological features like gonion flaring, muscular markings and shape of angle of symphysis menti. Result & Conclusion: It is concluded that bigonial breadth and bicondylar breadth exhibit the sexual dimorphism. Morphological Parameters: Gonion flaring, muscular markings and shape of angle of symphysis menti also demonstrate the sexual dimorphism. These parameters taken together may determine the sex of adult human mandibles. The present study shows that the mandible is an important tool in the determination of gender with high accuracy.展开更多
Diet composition and its ecological drivers are rarely investigated in coexisting closely related species.We used a molecular approach to characterize the seasonal variation in diet composition in four spiny lizard sp...Diet composition and its ecological drivers are rarely investigated in coexisting closely related species.We used a molecular approach to characterize the seasonal variation in diet composition in four spiny lizard species inhabiting a mountainous ecosystem.DNA metabarcoding revealed that the lizards Sceloporus aeneus,S.bicanthalis,S.grammicus,and S.spinosus mostly consumed arthropods of the orders Hemiptera,Araneae,Hymenoptera,and Coleoptera.The terrestrial lizards S.aeneus and S.bicanthalis mostly predated ants and spiders,whereas the arboreal–saxicolous S.grammicus and saxicolous S.spinosus largely consumed grasshoppers and leafhoppers.The taxonomic and phylogenetic diversity of the prey was higher during the dry season than the rainy season,likely because reduced prey availability in the dry season forced lizards to diversify their diets to meet their nutritional demands.Dietary and phylogenetic composition varied seasonally depending on the species,but only dietary composition varied with altitude.Seasonal dietary turnover was greater in S.spinosus than in S.bicanthalis,suggesting site-specific seasonal variability in prey availability;no other differences among species were observed.S.bicanthalis,which lives at the highest altitude in our study site,displayed interseasonal variation in diet breadth.Dietary differences were correlated with the species’feeding strategies and elevational distribution,which likely contributed to the coexistence of these lizard species in the studied geographic area and beyond.展开更多
This study intends to investigate the effects of receptive vocabulary breadth and depth on listening comprehension by college students. The experimental results indicate that both the breadth and depth have a signific...This study intends to investigate the effects of receptive vocabulary breadth and depth on listening comprehension by college students. The experimental results indicate that both the breadth and depth have a significant correlation with listening comprehension; vocabulary breadth contributes more to EFL learners＇ listening comprehension. The findings of this study give pedagogical implications for the teaching of listening in China.展开更多
基金funded by the National Basic Research Program of China (2009CB421303)the Key Project in Science & Technology Program of Xinjiang Uygur Autonomous Region (200933125)the Science and Technology Ministry Program (2009BAC54B03)
文摘The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impacted distributions and characteristics of dominant plant communities. However, besides groundwater depth, the community composition and species diversity were also influenced by physiognomy of the habitat. Based on the similarity coefficient, the differences between dominant plant communities were significant at different groundwater depths. Compared with other results relating to desert vegetation and groundwater depth, variations of community distribution were similar at the large spatial scale. However, in this extremely arid region, there were significant differences in community type and community succession when compared with other arid regions, especially in relationship to deep groundwater depth. With groundwater depth from deep to shallow, communities transformed with the sequence of Alhagi communities, Tamarix spp. communities, Populus communities, Phragmites communities, and Sophora communities. At groundwater depth of less than 6.0 m, the community type and composition changed, and the species diversity increased. Among these dominant species, Tamarix exhibited the biggest efficiency in resource utilization according to niche breadth, which means it possessed the best adaptability to environmental conditions at the oasis margins.
文摘Aims Although the niche concept is of prime importance in ecology,the quantification of plant species’niches remains difficult.Here we propose that plant functional traits,as determinants of species performance,may be useful tools for quantifying species niche parameters over environmental gradients.Important findings Under this framework,the mean trait values of a species determine its niche position along gradients,and intraspecific trait variability determines its niche breadth.This trait-based approach can provide an operational assessment of niche for a potentially large number of species,making it possible to understand and predict species niche shifts under environmental changes.We further advocate a promising method that recently appeared in the literature,which partitions trait diversity into among-and within-community components as a way to quantify the species niche in units of traits instead of environmental parameters.This approach allows the switch of the focus from ecological niches to trait niches,facilitating the examination of species coexistence along undefined environmental gradients.Altogether,the trait-based approach provides a promising toolkit for quantifying the species ecological niche and for understanding the evolution of species niche and traits.
基金Under the auspices of National Key Research and Development Program of China(No.2016YFC0500306)。
文摘This study aims to verify the concept of niches at multiple spatial scales in plant communities.To this end,we analyzed the niche characteristic of Rhododendron dauricum plant communities in Northeast China at three spatial scales.At the local scale,we calculated the Importance Value(IV)of species in five communities in the north of the Da Hinggan Mountains.At the intermediate scale,we examined five communities in their entirety,calculated the niche breadth of the species,and integrated niche overlap and interspecific association to analyze interspecific relationships.Further,the generalized additive model(GAM)was used to analyze the impact of topography and soil factors on niche characteristics.At the regional scale,we analyzed the geographical distribution of dominant species of R.dauricum plant communities in Northeast China and used principal component analysis(PCA)to analyze the impact of geographical and climate factors on species distribution.The results show that at the local scale,the IV of the species in each community varies widely.At the intermediate scale,species with a wide niche breadth tend to have a high value for IV.Larix gmelinii,Betula platyphylla,R.dauricum,Ledum palustre,and Vaccinium vitis-idaea had a relatively wide niche breadth and a high niche overlap,and the interspecific associations were almost all positive.Elevation and soil nutrients were the most dominant environmental factors.At the regional scale,species with a wide niche breadth tend to have a wide range of distribution,and temperature and precipitation were the most dominant environmental factors.This study suggests that the niche characteristics at three scales are both related and different.Niche characteristics at the local scale were various and labile,and niche characteristics at the intermediate and regional scales were relatively regular.These results show some degree of consistency with previous studies from an evolutionary perspective.The action mechanisms of these communities are related to differences in the dominan
基金Project (No. 30670014) supported by the National Natural Science Foundation of China
文摘Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then the co-relationship between genus species of soil dematiaceous hyphomycetes and ecosystem-types was analyzed. The results show that the amount and species distribution of soil dematiaceous hyphomycetes had an obvious variability in different ecosystem-types, and that the dominant genus species varied in the eight ecosystem-types studied, with Cladosporium being the dominant genus in seven of the eight ecosystem-types except wetland. The index of species diversity varied in different ecosystem-types. The niche breadth analysis showed that Cladosporium had the highest niche breadth and distributed in all ecosystem-types, while the genera with a narrow niche breadth distributed only in a few ecosystem-types. The results of niche overlap index analysis indicated that Stachybotrys and Torula, Doratomyces and Scolecobasidium, Cladosporium and Chrysosporium had a higher niche overlap, whereas Arthrinium and Gliomastix, Phialophora and Doratomyces, Oidiodendron and Ulocladium had no niche overlap.
文摘Background: In forensic science the identification of a human is based on three important factors: Age, Sex and Stature. Bones are an important tool for it and among human bones the pelvis and the skull are the most reliable source for sex determination. In the absence of complete pelvis, mandi-ble becomes the important source for sex determination since mandible is the most durable and movable part of skull that can resist postmortem changes. The present study is conducted to assess the accuracy and role of few metric and morphological parameters in determination of the sex of dry adult human mandible of North Indian origin. Material & Methods: The Study is conducted on 50 dry intact human adult mandibles of North Indian origin. The metric parameters i.e. bigonial breadth, bicondylar breadth are measured with a Vernier Calliper by two observers. Non-metric parameters being observed are the morphological features like gonion flaring, muscular markings and shape of angle of symphysis menti. Result & Conclusion: It is concluded that bigonial breadth and bicondylar breadth exhibit the sexual dimorphism. Morphological Parameters: Gonion flaring, muscular markings and shape of angle of symphysis menti also demonstrate the sexual dimorphism. These parameters taken together may determine the sex of adult human mandibles. The present study shows that the mandible is an important tool in the determination of gender with high accuracy.
基金Funding was provided by the Consejo Nacional de Ciencia y Tecnología(CONACyT)through the Infraestructura project(205945)the Ciencia de Frontera project(137748)+2 种基金the Cátedras CONACyT project(883)by the Universidad Nacional Autónoma de México(UNAM).M.H.received PhD scholarship(967648)S.H.-P.,postdoctoral grant(929602)from CONACyT.
文摘Diet composition and its ecological drivers are rarely investigated in coexisting closely related species.We used a molecular approach to characterize the seasonal variation in diet composition in four spiny lizard species inhabiting a mountainous ecosystem.DNA metabarcoding revealed that the lizards Sceloporus aeneus,S.bicanthalis,S.grammicus,and S.spinosus mostly consumed arthropods of the orders Hemiptera,Araneae,Hymenoptera,and Coleoptera.The terrestrial lizards S.aeneus and S.bicanthalis mostly predated ants and spiders,whereas the arboreal–saxicolous S.grammicus and saxicolous S.spinosus largely consumed grasshoppers and leafhoppers.The taxonomic and phylogenetic diversity of the prey was higher during the dry season than the rainy season,likely because reduced prey availability in the dry season forced lizards to diversify their diets to meet their nutritional demands.Dietary and phylogenetic composition varied seasonally depending on the species,but only dietary composition varied with altitude.Seasonal dietary turnover was greater in S.spinosus than in S.bicanthalis,suggesting site-specific seasonal variability in prey availability;no other differences among species were observed.S.bicanthalis,which lives at the highest altitude in our study site,displayed interseasonal variation in diet breadth.Dietary differences were correlated with the species’feeding strategies and elevational distribution,which likely contributed to the coexistence of these lizard species in the studied geographic area and beyond.
基金funded by the Philosophy and Social Science Foundation of Yunnan Province(No.YB2013072)
文摘This study intends to investigate the effects of receptive vocabulary breadth and depth on listening comprehension by college students. The experimental results indicate that both the breadth and depth have a significant correlation with listening comprehension; vocabulary breadth contributes more to EFL learners＇ listening comprehension. The findings of this study give pedagogical implications for the teaching of listening in China.
