The rhynchonellide brachiopod Dzieduszyckia Siemiradzki is widely distributed in the Lower Famennian strata,and exhibits a wide range of morphological variations among populations.1272 autochthonous Devonian Rongxian ...The rhynchonellide brachiopod Dzieduszyckia Siemiradzki is widely distributed in the Lower Famennian strata,and exhibits a wide range of morphological variations among populations.1272 autochthonous Devonian Rongxian Dzieduszyckia fossils were collected from three populations in South China,namely the Dazhai,Dalong,and Longmi sections.A series of quantitative morphological analyses were conducted to understand the morphological variation among populations and identify the triggers responsible for such variations.The results show that the Dazhai population differs significantly in morphospace from the Dalong and Longmi populations,while the latter two exhibit more similar morphological features,suggesting that geographic distribution may play a key role in affecting Dzieduszyckia morphology.The Longmi population shows a distinct morphospace from the Dazhai population and an overlapped morphospace with the Dalong population,indicating that habitat may not be the controlling factor.Lastly,the Dazhai and Dalong populations share some morphological similarities,but the Dazhai and Longmi populations occupy completely different morphospaces,indicating that evolution had a greater impact on phenotypic divergence than habitat.Our findings suggest that geographic distribution is the predominant factor influencing the morphological variation of Dzieduszyckia,while evolution and living habitat are less significant,the former of which might play a more important role.展开更多
The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a ...The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.展开更多
Background:Few studies have incorporated the evolutionary insights provided by analysis of phylogenetic structure along with community composition to assess the effects of exotic invasion on freshwater wetlands.Here,w...Background:Few studies have incorporated the evolutionary insights provided by analysis of phylogenetic structure along with community composition to assess the effects of exotic invasion on freshwater wetlands.Here,we assess the taxonomic and phylogenetic relationships among acid seep springs to investigate the potential homogenization or resistance of communities due to invasion of an exotic grass.Results:Multivariate community analyses indicated differences in community and phylogenetic composition and dispersion among acid seep springs,associated with gradients in soil moisture,canopy cover,and phylogenetic diversity.By contrast,univariate analyses showed differences in taxonomic diversity but not phylogenetic diversity among acid seep springs.Conclusions:Despite exotic invasion,individual acid seep springs remained taxonomically and phylogenetically distinct from each other.Taxonomic and phylogenetic diversity metrics revealed different aspects of composition,reinforcing the importance of including both in analyses of plant communities for understanding community assembly following exotic invasion and for management purposes.Within acid seep springs,taxonomic and phylogenetic composition appear to be driven more through environmental filtering by light and moisture than by the competitive effects following invasion of an exotic grass in support of Elton’s biotic resistance hypothesis.展开更多
基金the National Natural Science Foundation of China(Grant Nos.41772015 and 41672334)。
文摘The rhynchonellide brachiopod Dzieduszyckia Siemiradzki is widely distributed in the Lower Famennian strata,and exhibits a wide range of morphological variations among populations.1272 autochthonous Devonian Rongxian Dzieduszyckia fossils were collected from three populations in South China,namely the Dazhai,Dalong,and Longmi sections.A series of quantitative morphological analyses were conducted to understand the morphological variation among populations and identify the triggers responsible for such variations.The results show that the Dazhai population differs significantly in morphospace from the Dalong and Longmi populations,while the latter two exhibit more similar morphological features,suggesting that geographic distribution may play a key role in affecting Dzieduszyckia morphology.The Longmi population shows a distinct morphospace from the Dazhai population and an overlapped morphospace with the Dalong population,indicating that habitat may not be the controlling factor.Lastly,the Dazhai and Dalong populations share some morphological similarities,but the Dazhai and Longmi populations occupy completely different morphospaces,indicating that evolution had a greater impact on phenotypic divergence than habitat.Our findings suggest that geographic distribution is the predominant factor influencing the morphological variation of Dzieduszyckia,while evolution and living habitat are less significant,the former of which might play a more important role.
基金the Advisory Group on Inter-national Agricultural Research(BEAF)at the German Agency for International Cooperation(GIZ)within the German Ministry for Economic Cooperation(BMZ)for funding this research(project number 08.7860.3-001.00“Making the Mekong Con-nected”-MMC).
文摘The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.
基金Supported by the Natural Science Foundation of Guangxi(2014GXNSFBA118076)Fundamental Research Fund of Guangxi Institute of Botany(14001)Guangxi Open Fund For Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain(GKB15-A-12)
文摘Background:Few studies have incorporated the evolutionary insights provided by analysis of phylogenetic structure along with community composition to assess the effects of exotic invasion on freshwater wetlands.Here,we assess the taxonomic and phylogenetic relationships among acid seep springs to investigate the potential homogenization or resistance of communities due to invasion of an exotic grass.Results:Multivariate community analyses indicated differences in community and phylogenetic composition and dispersion among acid seep springs,associated with gradients in soil moisture,canopy cover,and phylogenetic diversity.By contrast,univariate analyses showed differences in taxonomic diversity but not phylogenetic diversity among acid seep springs.Conclusions:Despite exotic invasion,individual acid seep springs remained taxonomically and phylogenetically distinct from each other.Taxonomic and phylogenetic diversity metrics revealed different aspects of composition,reinforcing the importance of including both in analyses of plant communities for understanding community assembly following exotic invasion and for management purposes.Within acid seep springs,taxonomic and phylogenetic composition appear to be driven more through environmental filtering by light and moisture than by the competitive effects following invasion of an exotic grass in support of Elton’s biotic resistance hypothesis.
