Importance Of Dispersal Limitation Research Articles

Spatial Variation in Soil Fungal Communities across Paddy Fields in Subtropical China.

Fungi underpin almost all terrestrial ecosystem functions, yet our understanding of their community ecology lags far behind that of other organisms. Here, red paddy soils in subtropical China were collected across a soil depth profile, comprising 0-to-10-cm- (0-10cm-), 10-20cm-, and 20-40cm-deep layers. Using Illumina MiSeq amplicon sequencing of the internal transcribed spacer (ITS) region, distance-decay relationships (DDRs), and ecological models, fungal assemblages and their spatial patterns were investigated from each soil depth. We observed significant spatial variation in fungal communities and found that environmental heterogeneity decreased with soil depth, while spatial variation in fungal communities showed the opposite trend. DDRs occurred only in 0-10cm- and 10-20cm-deep soil layers, not in the 20-40cm layer. Our analyses revealed that the fungal community assembly in the 0-10cm layer was primarily governed by environmental filtering and a high dispersal rate, while in the deeper layer (20-40cm), it was primarily governed by dispersal limitation with minimal environmental filtering. Both environmental filtering and dispersal limitation controlled fungal community assembly in the 10-20cm layer, with dispersal limitation playing the major role. Results demonstrate the decreasing importance of environmental filtering and an increase in the importance of dispersal limitation in structuring fungal communities from shallower to deeper soils. Effectively, "everything is everywhere, but the environment selects," although only in shallower soils that are easily accessible to dispersive fungal propagules. This work highlights that perceived drivers of fungal community assembly are dependent on sampling depth, suggesting that caution is required when interpreting diversity patterns from samples that integrate across depths.IMPORTANCE In this work, Illumina MiSeq amplicon sequencing of the ITS region was used to investigate the spatial variation and assembly mechanisms of fungal communities from different soil layers across paddy fields in subtropical China, and the results demonstrate the decreasing importance of environmental filtering and an increase in the importance of dispersal limitation in structuring fungal communities from shallower to deeper soils. Therefore, the results of this study highlight that perceived drivers of fungal community assembly are dependent on sampling depth and suggest that caution is required when interpreting diversity patterns from samples that integrate across depths. This is the first study focusing on assemblages of fungal communities in different soil layers on a relatively large scale, and we thus believe that this study is of great importance to researchers and readers in microbial ecology, especially in microbial biogeography, because the results can provide sampling guidance in future studies of microbial biogeography.

Lake and catchment‐scale determinants of aquatic vegetation across almost 1,000 lakes and the contrasts between lake types

AbstractAimThe factors controlling macrophyte (aquatic plant) composition are complex, recent research having shown that the well‐studied effects of lake environmental factors (the so‐called “environmental filter”) can be constrained by hydrological and landscape factors. We investigated the factors determining macrophyte composition in lakes over water body and catchment scales and the transferability of this pattern across lake types.LocationAlmost 1,000 lakes distributed across Britain.TaxonLake macrophytes.MethodsLakes were partitioned into five types based on subdivision of alkalinity and elevation gradients. Data from botanical surveys were used to compare the spatial turnover and nestedness components of beta diversity between lake types. The relative importance of lake environment (based on local physicochemical data), hydrology (e.g. lake and stream density), landscape (e.g. fragmentation indices, land cover) and spatial autocorrelation in explaining variation in macrophyte composition were derived from variance partitioning.ResultsSpecies composition showed strong spatial structuring, suggestive of overland dispersal, enhanced by spatially correlated abiotic factors such as alkalinity and elevation. Catchment‐scale factors (e.g. land use, connectivity) promoted the establishment of different communities (more or less diverse, or differing in composition) but were of secondary importance. Turnover in composition between upland lakes was lower than in other lake types, reflecting a more specialist flora and increased potential for propagule exchange due to spatial aggregation and higher hydrological connectivity.Main conclusionsVegetation composition in lakes is more spatially structured than previously appreciated, consistent with the importance of dispersal limitation, but this does not apply evenly to all lakes, being most acute in lowland high alkalinity lakes. Thus, spatially structured abiotic factors, such as alkalinity, influence macrophyte composition most (suggestive of niche filtering) in high alkalinity lakes where human impacts tend to be greatest, although nestedness was also lowest in such lakes. By contrast, hydrological connectivity has a proportionally stronger structuring role in upland lakes.

The underlying processes of a soil mite metacommunity on a small scale.

Metacommunity theory provides an understanding of how ecological processes regulate local community assemblies. However, few field studies have evaluated the underlying mechanisms of a metacommunity on a small scale through revealing the relative roles of spatial and environmental filtering in structuring local community composition. Based on a spatially explicit sampling design in 2012 and 2013, this study aims to evaluate the underlying processes of a soil mite metacommunity on a small spatial scale (50 m) in a temperate deciduous forest located at the Maoershan Ecosystem Research Station, Northeast China. Moran’s eigenvector maps (MEMs) were used to model independent spatial variables. The relative importance of spatial (including trend variables, i.e., geographical coordinates, and broad- and fine-scale spatial variables) and environmental factors in driving the soil mite metacommunity was determined by variation partitioning. Mantel and partial Mantel tests and a redundancy analysis (RDA) were also used to identify the relative contributions of spatial and environmental variables. The results of variation partitioning suggested that the relatively large and significant variance was a result of spatial variables (including broad- and fine-scale spatial variables and trend), indicating the importance of dispersal limitation and autocorrelation processes. The significant contribution of environmental variables was detected in 2012 based on a partial Mantel test, and soil moisture and soil organic matter were especially important for the soil mite metacommunity composition in both years. The study suggested that the soil mite metacommunity was primarily regulated by dispersal limitation due to broad-scale and neutral biotic processes at a fine-scale and that environmental filtering might be of subordinate importance. In conclusion, a combination of metacommunity perspectives between neutral and species sorting theories was suggested to be important in the observed structure of the soil mite metacommunity at the studied small scale.

长白山针阔混交林不同演替阶段群落系统发育和功能性状结构

PDF HTML阅读 XML下载 导出引用 引用提醒 长白山针阔混交林不同演替阶段群落系统发育和功能性状结构 DOI: 10.5846/stxb201609141860 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划重点专项项目（2017YFC0504104）；国家自然科学基金项目（31670643） Phylogenetic development and functional structures during successional stages of conifer and broad-leaved mixed forest communities in Changbai Mountains, China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:群落构建一直是生态学研究的热点，基于系统发育和功能性状量化生境过滤、竞争排斥以及随机过程在群落构建中的作用，能够深入理解群落构建机制。本研究以长白山针阔混交林不同演替阶段的3个5.2 hm2样地（次生杨桦林、次生针阔混交林、原始椴树红松林）为平台，基于被子植物分类系统Ⅲ（Angiosperm Classification System，APGⅢ）构建的系统发育树和7个关键功能性状（叶面积、比叶面积、叶片厚度、叶片氮含量、叶片磷含量、氮磷比、最大树高），结合环境数据，分析不同演替阶段群落系统发育和功能性状结构。研究表明：（1）各演替阶段7个植物功能性状都表现出显著的系统发育信号，表明植物功能性状受系统发育历史影响；（2）系统发育和功能性状结构在不同演替阶段和不同径级均为非随机状态。随着演替的推进群落系统发育和功能性状结构由聚集走向发散；随着径级的增加，系统发育和功能性状结构的聚集程度减小，表明随着演替阶段的进行和径级增大，竞争性排斥的作用逐渐明显；（3）各演替阶段系统发育和功能性状的周转都为非随机且不同因子对两者的解释力度存在差异。演替早期空间距离的解释力度小于环境距离，说明生境过滤在群落构建中的重要性，而在演替后期空间距离的解释力度大于环境距离，验证了扩散限制在群落构建中的重要性。 Abstract:Community assembly has long been an important issue in community ecology. By quantifying the influence of habitat filtering, competitive exclusion, and random community assembly on the phylogenetic and functional traits, ecologists would gain a deeper understanding of community construction. In this study, based on the datasets of three 5.2 hm2 permanent plots at different successional stages (i.e., a Populus davidiana-Betula platyphylla secondary forest, a secondary conifer and broad-leaved mixed forest, and a Primary Tilia amurensis-Pinus koraiensis forest), we established the phylogenetic trees according to the Angiosperm Classification System (APG Ⅲ) and seven functional traits (i.e., leaf area, specific leaf area, leaf thickness, leaf nitrogen content, leaf phosphorus content, nitrogen-phosphorus ratio, and maximum tree height). We correlated the phylogenetic trees with the environmental variables to examine the patterns of the phylogenetic and functional structures of the forest communities at different successional stages in Changbai Mountains of China. The results showed that:(1) at each successional stage, significant phylogenetic signals were found for all seven functional traits, indicating that the functional traits were influenced by the phylogenetic history. (2) Both the phylogenetic and functional structures were non-random at all successional stages and stem classes. The phylogenetic and functional structures changed from "clustered" to "overdispersed" during the succession of forest community. Meanwhile, the degree of phylogenetic and functional clustering decreased with an increase in diameter class, indicating a significant increase in competitive exclusion with the succession of forest community. (3) The phylogenetic and functional turnovers were non-random, and the explanatory ability of the factors to interpret the phylogenetic and functional turnover was different. In the early succession stage, the spatial distance explained more than the environmental distance, indicating the importance of habitat filtering in community assembly. However, in the late succession stage, the environmental distance explained more than the spatial distance, indicating the importance of dispersal limitation in community assembly. 参考文献 相似文献 引证文献

Species Sorting of Benthic Invertebrates in a Salinity Gradient - Importance of Dispersal Limitation.

The relative importance of environment and dispersal related processes for community assembly has attracted great interest over recent decades, but few empirical studies from the marine/estuarine realm have examined the possible effects of these two types of factors in the same system. Importance of these processes was investigated in a hypothetical metacommunity of benthic invertebrates in 16 micro-tidal estuaries connected to the same open sea area. The estuaries differed in size and connectivity to the open sea and represented a salinity gradient across the estuaries. The Elements of Metacommunity Structure (EMS) approach on estuary scale was complemented with a mechanistic variance partitioning approach on sample scale to disentangle effects of factors affecting assembly of three trait groups of species with different dispersivity. A quasi-Clementsian pattern was observed for all three traits, a likely response to some latent gradient. The primary axis in the pattern was most strongly related to gradients in estuary salinity and estuary entrance width and correlation with richness indicated nestedness only in the matrix of the most dispersive trait group. In the variance partitioning approach measures of turnover and nestedness between paired samples each from different estuaries were related to environmental distance in different gradients. Distance between estuaries was unimportant suggesting importance of factors characterizing the estuaries. While the high dispersive species mainly were sorted in the salinity gradient, apparently according to their tolerance ranges towards salinity, the two less dispersive traits were additionally affected by estuary entrance width and possibly also area. The results exemplify a mechanism of community assembly in the marine realm where the niche factor salinity in conjunction with differential dispersal structure invertebrates in a metacommunity of connected estuaries, and support the idea that dispersive species are more controlled by the environment than less dispersive species.

Measuring ectomycorrhizal fungal dispersal: macroecological patterns driven by microscopic propagules

Dispersal plays a prominent role in most conceptual models of community assembly. However, direct measurement of dispersal across a whole community is difficult at ecologically relevant spatial scales. For cryptic organisms, such as fungi and bacteria, the scale and importance of dispersal limitation has become a major point of debate. We use an experimental island biogeographic approach to measure the effects of dispersal limitation on the ecological dynamics of an important group of plant symbionts, ectomycorrhizal fungi. We manipulated the isolation of uncolonized host seedlings across a natural landscape and used a range of molecular techniques to measure the dispersal rates of ectomycorrhizal propagules and host colonization. Some species were prolific dispersers, producing annual spore loads on the order of trillions of spores per km(2). However, fungal propagules reaching host seedlings decreased rapidly with increasing distance from potential spore sources, causing a concomitant reduction in ectomycorrhizal species richness, host colonization and host biomass. There were also strong differences in dispersal ability across species, which correlated well with the predictable composition of ectomycorrhizal communities associated with establishing pine forest. The use of molecular tools to measure whole community dispersal provides a direct confirmation for a key mechanism underlying island biogeography theory and has the potential to make microbial systems a model for understanding the role of dispersal in ecological theory.