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鉴于全球森林均呈现片段化(破碎化)的分布状态, 理解片段化森林群落构建的过程很有必要。该文通过综述群落构建的主要生态过程如生态漂变、扩散、选择和物种形成等在片段化森林群落构建中的相对作用, 发现因片段化森林形成方式的不同, 重构群落(片段化生境中通过次生演替重新形成的森林群落)和解构群落(原有森林被片段化后形成的森林群落)在不同演替阶段所受到的主要生态过程的相对作用有所不同。虽然利用基于群落内物种分布格局推测构建过程(如物种多度分布、零模型结合β多样性的方法、功能特征的收敛和发散等)、人工控制实验、群落结构动态分析等方法对片段化森林中群落构建的过程进行了有效的检验, 但是针对片段化森林群落构建过程的实验性研究仍然不足。未来有待在理论模型、群落构建过程的检验以及理论与物种保护相结合等方面继续开展深入的研究。 相似文献
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群落构建机制是生态学研究的核心论题。生态位理论和中性理论是阐明群落构建的两种主要理论, 但这两种理论分别强调的环境过滤和扩散限制对群落构建的影响尚存争议。该研究以黄土高原人工林下草本层群落为研究对象, 将群落物种组成数据与地理空间、气候、地形以及生物因子相结合, 运用随机森林模型(RF)和基于距离矩阵的多元回归方法(MRM), 探究了各个因子的重要性, 并通过邻体主坐标矩阵(PCNM)和基于距离的冗余分析(db-RDA)分别筛选显著的空间结构和环境因子, 最后结合筛选出的PCNM特征值和环境变量进行变差分解。研究结果显示: 1)林下草本层群落组成相似性随地理距离和生境差异的增加而减小。2)地理距离与生境差异共同解释了群落组成相似性变化的47.8%。其中, 空间因子和环境因子的独立解释率分别为14.1%和9.8%, 两者的联合解释率为23.9%。3)地理距离和年降水量是引起研究区内物种组成变化的关键因子, 且地理距离的重要性大于年降水量。在黄土高原腹地, 扩散限制与环境过滤共同主导了人工林下草本层群落的构建过程。 相似文献
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Markus Gastauer Amílcar Walter Saporetti‐Junior Luiz Fernando Silva Magnago Jeannine Cavender‐Bares Joo Augusto Alves Meira‐Neto 《Ecology and evolution》2015,5(22):5272-5283
Allopatric or sympatric speciation influence the degree to which closely related species coexist in different manners, altering the patterns of phylogenetic structure and turnover among and between communities. The objective of this study was to examine whether phylogenetic community structure and turnover in the Brazilian Atlantic Forest permit conclusions about the dominant process for the formation of extant angiosperm richness of tree species. Therefore, we analyzed phylogenetic community structure (MPD, MNTD) as well as taxonomic (Jaccard similarity) and phylogenetic turnover (betaMPD, betaMNTD) among and between 49 tree communities distributed among three different habitat types. Mean annual precipitation and mean annual temperature in each survey area were estimated. Phylogenetic community structure does not differ between habitat types, although MPD reduces with mean annual temperature. Jaccard similarity decreases and betaMNTD increases with spatial distance and environmental differences between study sites. Spatial distance explains the largest portions of variance in the data, indicating dispersal limitation and the spatial aggregation of recently formed taxa, as betaMNTD is related to more recent evolutionary events. betaMPD, that is related to deep evolutionary splits, shows no spatial or environmental pattern, indicating that older clades are equally distributed across the Brazilian Atlantic Forest. While similarity pattern indicates dispersal limitations, the spatial turnover of betaMNTD is consistent with a high degree of sympatric speciation generating extant diversity and endemism in the Brazilian Atlantic Forest. More comprehensive approaches are necessary to reduce spatial sampling bias, uncertainties regarding angiosperm diversification patterns and confirm sympatric speciation as the dominant generator for the formation of extant species diversity in the Brazilian Atlantic Forest. 相似文献
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Anchi Wu Xiangwen Deng Honglin He Xiaoli Ren Yiran Jing Wenhua Xiang Shuai Ouyang Wende Yan Xi Fang 《Ecology and evolution》2019,9(9):5338-5347
To quantify and assess the processes underlying community assembly and driving tree species abundance distributions(SADs) with spatial scale variation in two typical subtropical secondary forests in Dashanchong state‐owned forest farm, two 1‐ha permanent study plots (100‐m × 100‐m) were established. We selected four diversity indices including species richness, Shannon–Wiener, Simpson and Pielou, and relative importance values to quantify community assembly and biodiversity. Empirical cumulative distribution and species accumulation curves were utilized to describe the SADs of two forests communities trees. Three types of models, including statistic model (lognormal and logseries model), niche model (broken‐stick, niche preemption, and Zipf‐Mandelbrodt model), and neutral theory model, were estimated by the fitted SADs. Simulation effects were tested by Akaike's information criterion (AIC) and Kolmogorov–Smirnov test. Results found that the Fagaceae and Anacardiaceae families were their respective dominance family in the evergreen broad‐leaved and deciduous mixed communities. According to original data and random sampling predictions, the SADs were hump‐shaped for intermediate abundance classes, peaking between 8 and 32 in the evergreen broad‐leaved community, but this maximum increased with size of total sampled area size in the deciduous mixed community. All niche models could only explain SADs patterns at smaller spatial scales. However, both the neutral theory and purely statistical models were suitable for explaining the SADs for secondary forest communities when the sampling plot exceeded 40 m. The results showed the SADs indicated a clear directional trend toward convergence and similar predominating ecological processes in two typical subtropical secondary forests. The neutral process gradually replaced the niche process in importance and become the main mechanism for determining SADs of forest trees as the sampling scale expanded. Thus, we can preliminarily conclude that neutral processes had a major effect on biodiversity patterns in these two subtropical secondary forests but exclude possible contributions of other processes. 相似文献
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Steven W. Kembel 《Ecology letters》2009,12(9):949-960
Patterns of phylogenetic relatedness within communities have been widely used to infer the importance of different ecological and evolutionary processes during community assembly, but little is known about the relative ability of community phylogenetics methods and null models to detect the signature of processes such as dispersal, competition and filtering under different models of trait evolution. Using a metacommunity simulation incorporating quantitative models of trait evolution and community assembly, I assessed the performance of different tests that have been used to measure community phylogenetic structure. All tests were sensitive to the relative phylogenetic signal in species metacommunity abundances and traits; methods that were most sensitive to the effects of niche-based processes on community structure were also more likely to find non-random patterns of community phylogenetic structure under dispersal assembly. When used with a null model that maintained species occurrence frequency in random communities, several metrics could detect niche-based assembly when there was strong phylogenetic signal in species traits, when multiple traits were involved in community assembly, and in the presence of environmental heterogeneity. Interpretations of the causes of community phylogenetic structure should be modified to account for the influence of dispersal. 相似文献
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We develop a statistical method to infer the parameters of Hubbell's neutral model of biodiversity using data on local species abundances and their phylogenetic relatedness. This method uses the approximate Bayesian computation (ABC) approach, where the data are summarized into a small number of informative summary statistics. We used three statistics: the number of species in the sample, Shannon H index of evenness and Shao and Sokal's B 1 index of phylogenetic tree imbalance. Our approach was found to outperform previous methods, illustrating the potential of ABC methods in ecology. Applying it to four large tropical forest tree data sets, the best-fit immigration rates m were found to be two orders of magnitude smaller and regional diversities θ larger than previously reported for the same data. This implies that neutral-compatible regional pools of tropical trees should extend over continental scales, and that m measures, in this context, mostly the frequency of long-distance dispersal events. 相似文献
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One of the central goals of community ecology is to understand the forces that maintain species diversity within communities. The traditional niche-assembly theory asserts that species live together in a community only when they differ from one another in resource uses. But this theory has some difficulties in explaining the diversity often observed in specie-rich communities such as tropical forests. As an alternative to the niche theory, Hubbell and other ecologists introduced a neutral model. Hubbell argues that the number of species in a community is controlled by species extinction and immigration or speciation of new species. Assuming that all individuals of all species in a trophically similar community are ecologically equivalent, Hubbell’s neutral theory predicts two important statistical distributions. One is the asymptotic log-series distribution for the metacommunities under point mutation speciation, and the other is the zero-sum multinomial distribution for both local communities under dispersal limitation and metacommunities under random fission speciation. Unlike the niche-assembly theory, the neutral theory takes similarity in species and individuals as a starting point for investigating species diversity. Based on the fundamental processes of birth, death, dispersal and speciation, the neutral theory provided the first mechanistic explanation of species abundance distribution commonly observed in natural communities. Since the publication of the neutral theory, there has been much discussion about it, pro and con. In this paper, we summarize recent progress in the assumption, prediction and speciation mode of the neutral theory, including progress in the theory itself, tests about the assumption of the theory, prediction and speciation mode at the metacommunity level. We also suggest that the most important task in the future is to bridge the niche-assembly theory and the neutral theory, and to add species differences to the neutral theory and more stochasticity to the niche theory. __________ Translated from Journal of Plant Ecology, 2006, 30(5): 868–877 [译自:植物生态学报] 相似文献
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One of the central goals of community ecology is to understand the forces that maintain species diversity within communities. The traditional niche-assembly theory asserts that species live together in a community only when they differ from one another in resource uses. But this theory has some difficulties in explaining the diversity often observed in specie-rich communities such as tropical forests. As an alternative to the niche theory, Hubbell and other ecologists introduced a neutral model. Hubbell argues that the number of species in a community is controlled by species extinction and immigration or speciation of new species. Assuming that all individuals of all species in a trophically similar com-munity are ecologically equivalent, Hubbell's neutral theory predicts two important statistical distributions. One is the asymptotic log-series distribution for the metacommunities under point mutation speciation, and the other is the zero-sum multinomial distribution for both local communities under dispersal limitation and metacommunities under random fission speciation. Unlike the niche-assembly theory, the neutral theory takes similarity in species and individuals as a starting point for investigating species diversity. Based on the fundamental processes of birth, death, dispersal and spe-ciation, the neutral theory provided the first mechanistic explanation of species abundance distribution commonly observed in natural communities. Since the publication of the neutral theory, there has been much discussion about it, pro and con. In this paper, we summarize recent progress in the assumption, prediction and speciation mode of the neutral theory, including progress in the theory itself, tests about the assumption of the theory, prediction and speciation mode at the metacommunity level. We also suggest that the most important task in the future is to bridge the niche-assembly theory and the neutral theory, and to add species differences to the neutral theory and more stochasticity to the niche theory. 相似文献
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Francesco de Bello 《Global Ecology and Biogeography》2012,21(3):312-317
The relevance of neutral versus niche‐based community assembly rules (i.e. the processes sorting species present in a larger geographical region into local communities) remains to be demonstrated in ecology and biogeography. To attempt to do this, a number of complex null models are increasingly being used that compare observed community functional diversity (FD, i.e. the extent of trait dissimilarity between coexisting species) with randomly simulated FD. However, little is known about the performance of these null models in detecting non‐neutral community assembly rules such as trait convergence and divergence of communities (supposedly revealing habitat selection and limiting similarity, respectively). Here, using both simulated and field communities, I show that assembly rule detection varies systematically with the magnitude of the observed FD, so that these null models do not really succeed in breaking down the observed functional relationships between species. This is a particular concern, making detection of community assembly dependent on: (1) the pool of samples considered, and (2) the capacity of observed FD to correctly discriminate these rules. Null models should be more thoroughly described and validated before being considered as a magic wand to reveal assembly patterns. 相似文献
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地理距离及环境差异对云南元江干热河谷植物群落beta多样性的影响 总被引:2,自引:0,他引:2
beta多样性反映了群落间物种组成的差异, 是生物多样性研究的热点之一。本研究通过对云南元江干热河谷41个植物群落样方进行调查, 用Jaccard相异系数表征物种beta多样性, 用样方之间的最近谱系距离(mean nearest taxon distance, MNTD)及平均谱系距离(mean pairwise distance, MPD)表征谱系beta多样性, 采用基于距离矩阵的多元回归和方差分解方法, 探讨了该区域干热河谷典型植物群落的物种beta多样性和谱系beta多样性与样方间环境差异(主要是气候)及地理距离之间的关系。结果表明: (1)群落间的地理距离和年平均温度差异对干热河谷植物群落的物种beta多样性和谱系beta多样性有显著影响; (2)地理距离对物种beta多样性和MNTD的影响最大; 地理距离和年平均温度差异对MPD的影响均较大; (3)样方间年平均温度与年平均降水量的差异和地理距离能够解释群落间beta多样性及谱系beta多样性11-13%的变异。以上结果表明, 生态位分化和扩散限制对该地区植物群落的beta多样性均有显著影响, 其中扩散限制的影响可能更大。此外, 人类活动等其他因素也很可能对元江干热河谷的群落组成具有非常重要的影响。 相似文献
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Vascular epiphytes form a diverse group of almost 30 000 species, yet theory concerning their community structure is still largely lacking. We therefore employed the simplest models of biodiversity, (near-)neutral models, to generate hypotheses concerning their community structure. With recently developed tools for (near-)neutral models we analyzed species abundance data from many samples in Central and South America which we divided into four metacommunities (Mesoamerica, Central America, Amazonia and Paraná), where for each metacommunity we considered two subsets differing in dispersal syndrome: an animal-dispersed guild and a wind-dispersed guild. We considered three models differing in the underlying speciation mode. Across all metacommunities, we found observed patterns to be indistinguishable from patterns generated by neutral or near-neutral processes. Furthermore, we found that subdivision in different dispersal guilds was often supported, with recruitment limitation being stronger for animal-dispersed species than for wind-dispersed species. This is the first time that (near-)neutral theory has been applied to epiphyte communities. Future efforts with additional data sets and more refined models are expected to further improve our understanding of community structure in epiphytes and will have to test the generality of our findings. 相似文献
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JUSTIN R. MEYER ELLINOR MICHEL PETER B. McINTYRE BRITTANY E. HUNTINGTON DUSTIN J. LONG GENIFER LARA 《Freshwater Biology》2011,56(10):2082-2093
1. Ecologists continue to debate whether the assembly of communities of species is more strongly influenced by dispersal limitations or niche‐based factors. Analytical approaches that account for both mechanisms can help to resolve controls of community assembly. 2. We compared littoral snail assemblages in Lake Tanganyika at three different spatial scales (5–25 m, 0.5–10 km and 0.5–27 km) to test whether spatial distance or environmental differences are better predictors of community similarity. 3. At the finest scale (5–25 m), snail assemblages shifted strongly with depth but not across similar lateral distances, indicating a stronger response to environmental gradients than dispersal opportunities. 4. At the two larger scales (0.5–27 km), both environmental similarity and shoreline distance between sites predicted assemblage similarity across sites. Additionally, canonical correspondence analysis revealed that snail abundances were significantly correlated with algal carbon‐to‐nitrogen ratio and wave energy. 5. Our results indicate that the factors governing assemblage structure are scale dependent; niche‐based mechanisms act across all spatial scales, whereas community similarity declines with distance only at larger spatial separations. 相似文献
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Andrés Baselga Jorge M. Lobo Jens‐Christian Svenning Miguel B. Araújo 《Journal of Biogeography》2012,39(4):760-771
Aim Do species range shapes follow general patterns? If so, what mechanisms underlie those patterns? We show for 11,582 species from a variety of taxa across the world that most species have similar latitudinal and longitudinal ranges. We then seek to disentangle the roles of climate, extrinsic dispersal limitation (e.g. barriers) and intrinsic dispersal limitation (reflecting a species’ ability to disperse) as constraints of species range shape. We also assess the relationship between range size and shape. Location Global. Methods Range shape patterns were measured as the slope of the regression of latitudinal species ranges against longitudinal ranges for each taxon and continent, and as the coefficient of determination measuring the degree of scattering of species ranges from the 1:1 line (i.e. latitudinal range = longitudinal range). Two major competing hypotheses explaining species distributions (i.e. dispersal or climatic determinism) were explored. To this end, we compared the observed slopes and coefficients of determination with those predicted by a climatic null model that estimates the potential range shapes in the absence of dispersal limitation. The predictions compared were that species distribution shapes are determined purely by (1) intrinsic dispersal limitation, (2) extrinsic dispersal limitations such as topographic barriers, and (3) climate. Results Using this methodology, we show for a wide variety of taxa across the globe that species generally have very similar latitudinal and longitudinal ranges. However, neither neutral models assuming random but spatially constrained dispersal, nor models assuming climatic control of species distributions describe range shapes adequately. The empirical relationship between the latitudinal and longitudinal ranges of species falls between the predictions of these competing models. Main conclusions We propose that this pattern arises from the combined effect of macroclimate and intrinsic dispersal limitation, the latter being the major determinant among restricted‐range species. Hence, accurately projecting the impact of climate change onto species ranges will require a solid understanding of how climate and dispersal jointly control species ranges. 相似文献
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灌丛是太行山地区最重要的生态系统类型之一, 灌丛群落生物多样性的维持及其生态系统服务功能对京津冀地区的生态安全具有重要作用。本研究选择太行山最具代表性的两种灌木群落——荆条(Vitex negundo var. heterophylla)灌丛和三裂绣线菊(Spiraea trilobata)灌丛为研究对象, 利用净亲缘关系指数(net relatedness index, NRI)和多元回归等方法探究了两种灌丛群落构建机制的异同及主要的环境影响因子, 同时还利用谱系结构主坐标分析(principal coordinates of phylogenetic structure, PCPS)对决定群落谱系结构的关键系统发育节点进行了探究。结果表明: 两种灌丛群落内灌木植物的物种多样性没有显著差异, 但谱系结构差异显著。三裂绣线菊群落表现出显著的谱系发散趋势, 而荆条群落谱系聚集程度高于三裂绣线菊群落, 但未表现出显著的谱系结构。三裂绣线菊灌丛群落构建的驱动机制是生态位分化, 荆条灌丛中生境过滤作用有所增加, 与生态位分化共同驱动其群落构建过程。与干旱胁迫相关的生境过滤因素增加是荆条灌丛群落谱系聚集程度增加的重要原因。PCPS二维排序结果表明: 荆条灌丛群落谱系趋向聚集与其群落内缺乏蔷薇目、壳斗目等亲缘关系较远的类群有关, 而三裂绣线菊灌丛群落内物种则包含较多的演化分支。总体而言, 环境过滤不是决定太行山地区灌丛群落构建的主要驱动因素, 但水分条件仍然是影响区域群落谱系结构的重要因素。 相似文献
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Analytical methods are now available that can date all nodes in a molecular phylogenetic tree with one calibration, and which correct for variable rates of DNA substitution in different lineages. Although these techniques are approximate, they offer a new tool to investigate the historical construction of species-rich biomes. Dated phylogenies of globally distributed plant families often indicate that dispersal, even across oceans, rather than plate tectonics, has generated their wide distributions. By contrast, there are indications that animal lineages have undergone less long distance dispersal. Dating the origin of biome-specific plant groups offers a means of estimating the age of the biomes they characterize. However, rather than a simple emphasis on biome age, we stress the importance of studies that seek to unravel the processes that have led to the accumulation of large numbers of species in some biomes. The synthesis of biological inventory, systematics and evolutionary biology offered by the frameworks of neutral ecological theory and phylogenetic community structure offers a promising route for future work. 相似文献
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甲虫作为节肢动物中一个庞大的类群,具有繁简各异的生活习性,在生态系统中发挥极为重要的作用.甲虫群落构建是群落生态研究的重要内容之一,可揭示不同生态环境下生物多样性的形成与维持机制.现阶段对甲虫群落构建的研究主要通过物种的功能性状,或将系统发育结构与物种功能性状相结合的方法,对群落构建过程进行解析,用以判断主要的驱动因素... 相似文献
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A major goal of microbial community ecology is to understand the forces that structure community composition. Deterministic selection by specific environmental factors is sometimes important, but in other cases stochastic or ecologically neutral processes dominate. Lacking is a unified conceptual framework aiming to understand why deterministic processes dominate in some contexts but not others. Here we work toward such a framework. By testing predictions derived from general ecological theory we aim to uncover factors that govern the relative influences of deterministic and stochastic processes. We couple spatiotemporal data on subsurface microbial communities and environmental parameters with metrics and null models of within and between community phylogenetic composition. Testing for phylogenetic signal in organismal niches showed that more closely related taxa have more similar habitat associations. Community phylogenetic analyses further showed that ecologically similar taxa coexist to a greater degree than expected by chance. Environmental filtering thus deterministically governs subsurface microbial community composition. More importantly, the influence of deterministic environmental filtering relative to stochastic factors was maximized at both ends of an environmental variation gradient. A stronger role of stochastic factors was, however, supported through analyses of phylogenetic temporal turnover. Although phylogenetic turnover was on average faster than expected, most pairwise comparisons were not themselves significantly non-random. The relative influence of deterministic environmental filtering over community dynamics was elevated, however, in the most temporally and spatially variable environments. Our results point to general rules governing the relative influences of stochastic and deterministic processes across micro- and macro-organisms. 相似文献