共查询到20条相似文献，搜索用时 15 毫秒
1.
Aim To investigate species compositions, rates of species turnover, species–area and species–distance relationships and patterns of nestedness in the floras of small Bahamian islands, by comparing two groups of islands that had been differentially affected by two hurricanes. Location Small islands occurring on either side of Great Exuma near Georgetown, Bahamas. Methods We surveyed the plant species of 44 small islands over a 5‐year period from 1998 to 2002. Hurricanes Lili and Michelle occurred in 1996 and 2001, respectively; both storms affected small islands on the more exposed south‐west side of Great Exuma to a greater degree than small islands on the more protected north‐east side. A set of 27 islands was surveyed in 1998 and 2002 to evaluate species turnover. Stepwise multiple linear regression analyses and an information‐theoretic approach (the Akaike information criterion) were used to elucidate the importance of area and distance as predictors of plant species number. We compared a piecewise linear regression model with a simple linear regression of species number against area to determine whether a small island effect existed. Nestedness patterns were evaluated by Wilcoxon two‐sample tests to analyse occurrence sequences. Results Species turnover was low in an absolute sense (overall = 0.74% year?1), yet was over three times higher than that documented in a nearby archipelago in the absence of hurricanes. Both vegetated area and distance were important predictor variables for exposed islands but not for protected islands. Some support was found for a small island effect for the exposed islands based on a piecewise linear regression model. Both island groups revealed significant nestedness at the level of the assemblage (both P < 0.001). On exposed islands, 65–79% (depending upon the method of calculation) of all species were significantly nested, but only 47% of all species were significantly nested on protected islands. Main conclusions Overall, these insular floras seem highly resistant to hurricane‐force disturbances. Species turnover was low (< 1% year?1) in an absolute sense, particularly in comparison with rates for other taxa. Higher degrees of nestedness and significant species–area and species–distance relationships for exposed islands indicated stronger patterns of community assembly. It is likely that disturbance is a major structuring force for the exposed islands, although the type of disturbances that mediate these patterns may not be primarily hurricane‐force storms. 相似文献
2.
理解沿环境或空间梯度的群落组成变化(即beta多样性)一直是生态学和保护生物学的中心问题, 且beta多样性的形成机制及其对环境的响应已成为当前生物多样性研究的热点问题。本文以西藏横断山区怒江和澜沧江两个流域入江溪流中的细菌为研究对象, 使用Baselga的beta多样性分解方法, 基于Sørensen相异性指数将细菌的beta多样性分解为周转(turnover)和嵌套(nestedness)两个组分, 探究了细菌beta多样性及其分解组分随海拔距离的分布模式, 并且衡量了环境、气候和空间因子的相对重要性。结果表明, 两个流域中细菌的群落结构显著不同。两个流域的细菌总beta多样性和周转组分随海拔距离的增加而增加, 周转组分占总beta多样性的比例较大。气候和环境因子是两个流域中细菌总beta多样性及周转过程的重要预测因子, 并且所有的显著因子均为正相关, 其中环境因子中相关性最高的为海拔距离(R 2= 0.408, P < 0.001), 而气候因子中相关性最高的为年均温差(R 2= 0.417, P < 0.001)。方差分解结果暗示嵌套组分主要受空间扩散的影响; 总beta多样性和周转组分在环境较恶劣的澜沧江主要受环境过滤的影响, 而在环境较温和的怒江主要受空间扩散和环境过滤的共同影响。此外, 较为恶劣的环境条件会增加细菌的总beta多样性和周转率, 并且会形成更强的环境筛选作用去影响细菌群落的物种组成。我们的研究表明对西藏横断山区水体细菌多样性的保护需要从整个流域入手, 而非少量的生物多样性热点地区。 相似文献
3.
4.
Determinants of plant species richness on small Bahamian islands 总被引：2，自引：0，他引：2
Lloyd W. Morrison 《Journal of Biogeography》2002,29(7):931-941
5.
Fredrik Dalerum Tarryn Anne Retief Carl Peter Havemann Christian T. Chimimba Berndt Janse van Rensburg 《Ecology and evolution》2019,9(1):154-165
Studies of biodiversity along environmental gradients provide information on how ecological communities change in response to biotic and abiotic factors. For instance, distance to water is associated with several factors that shape the structure and the functioning of ecosystems at a range of spatial scales. We investigated the influence of distance to a perennial water source on ant communities in a semi‐arid savanna in northern Botswana. Ant abundance, taxonomic richness, and both alpha and beta diversity were generally higher during the wet than the dry season. However, there were strong seasonal influences on the effects of distance to water, with more pronounced effects during the wet season. While both abundance and beta diversity declined with increasing distances to water during the wet season, there was a contrasting increase in alpha diversity. There was no major effect of distance to water on taxonomic richness during either season. Beta diversity was as high across as along gradients, and we found support for modular rather than nested community structures along gradients. Our study demonstrated that small‐scale gradients in distance to water can influence several aspects of ant communities in semi‐arid savannas. However, our results also point to strong effects of small‐scale environmental variation, for instance associated with vegetation characteristics, soil properties, and plant community structure that are not directly linked to water access. 相似文献
6.
土壤动物可能会与植物形成复杂的互作网络,有关其对海拔梯度做出响应的研究还相对较少,了解不同生境下的生态网络为理解和预测系统的稳定性及其动态变化机制提供了新途径。于北京东灵山地区调查了沿海拔梯度凋落物层与土壤层中的土壤动物以及木本和草本植物的多样性,并通过零模型的方法对比了土壤动物-植物互作网络特征参数的标准化效应值在高-中-低三个海拔段的差异。结果显示：土壤动物的稀有类群在中海拔段多样性较高,木本植物多样性随海拔降低,而草本植物多样性则随海拔升高。各生物类群组成都随海拔距离而增加,存在明显的聚集性分布格局。植物与土壤动物之间的互作网络特征参数不仅随海拔改变,且在凋落物与土壤层之间、木本与草本植物之间存在差异。总体而言,土壤动物与木本植物互作网络的海拔变化主要与土壤动物多样性有关,而与草本的互作网络则与草本植物多样性有关。沿海拔梯度,存在土壤动物-木本植物向土壤动物-草本植物网络的适应性转变。本研究在同一海拔梯度上探讨了不同层土壤动物与植物的互作关系,对深入理解山地生态系统中各生物类群的共存机制具有重要意义。 相似文献
7.
Carolina S. Ramos M. Isabel Bellocq Carolina I. Paris Julieta Filloy 《Austral ecology》2018,43(4):424-434
Understanding the underlying mechanisms causing diversity patterns is a fundamental objective in ecology and science‐based conservation biology. Energy and environmental‐heterogeneity hypotheses have been suggested to explain spatial changes in ant diversity. However, the relative roles of each one in determining alpha and beta diversity patterns remain elusive. We investigated the main factors driving spatial changes in ant (Hymenoptera, Formicidae) species richness and composition (including turnover and nestedness components) along a 500 km longitudinal gradient in the Pampean region of Argentina. Ants were sampled using pitfall traps in 12 sample sites during the summer. We performed a model selection approach to analyse responses of ant richness and composition dissimilarity to environmental factors. Then, we computed a dissimilarity partitioning of the contributions of spatial turnover and nestedness to total composition dissimilarity. Temporal habitat heterogeneity and temperature were the primary factors explaining spatial patterns of epigean ant species richness across the Pampas. The distance decay in species composition similarity was best accounted by temperature dissimilarity, and turnover had the greatest contribution to the observed beta diversity pattern. Our findings suggest that both energy and environmental‐heterogeneity‐related variables are key factors shaping richness patterns of ants and niche‐based processes instead of neutral processes appear to be regulating species composition of ant assemblages. The major contribution of turnover to the beta diversity pattern indicated that lands for potential reconversion to grassland should represent the complete environmental gradient of the Pampean region, instead of prioritizing a single site with high species richness. 相似文献
8.
Spyros Sfenthourakis Sinos Giokas† Evangelos Tzanatos 《Global Ecology and Biogeography》2004,13(1):23-35
Aim To investigate the formation of nestedness and species co‐occurrence patterns at the local (sampling station), the intermediate (island group), and the archipelago scale. Location The study used data on the distribution of terrestrial isopods on 20 islands of the central Aegean (Greece). These islands are assigned to two distinct subgroups (Kyklades and Eastern islands). Methods The Nestedness Temperature Calculator was used to obtain nestedness values and maximally nested matrices, the EcoSim7 software and a modified version of Sanderson (2000 ) method were used for the analysis of species co‐occurrences. Idiosyncratic temperatures of species and the order of species placement in the maximally nested matrices were used for further comparisons among spatial scales. The relationships of nestedness values with beta‐diversity, habitat diversity and a number of ecological factors recorded for each sampling station were also investigated. Results Significant nestedness was found at all spatial scales. Levels of nestedness were not related to beta‐diversity or habitat diversity. Nestedness values were similar among spatial scales, but they were affected by matrix size. The species that contributed most to the nested patterns within single islands were not the same as those that produce nestedness at the archipelago scale. There was significant variation in the frequency of species occurrence among islands and among spatial scales. There was no direct effect of ecological factors on the shaping of patterns of nestedness within individual islands, but habitat heterogeneity was crucial for the existence of such patterns. Positive associations among species prevailed at all scales when species per station were considered, while negative associations prevailed in the species per island matrices. All associations resulted from the habitat structure of sampling stations and from particularities of geographical distributions. Conclusions There was no clear‐cut distinction between nestedness patterns among spatial scales, even though different species, and partially different factors, contributed to the formation of these patterns in each case. There was a core of species that contributed to the formation of nested patterns at all spatial scales, while the patterns of species associations suggested that biotic interactions are not an important causal factor. The results of this study suggest that locally rare species cannot be widespread at a higher spatial scale, while locally common species can have a restricted distribution. 相似文献
9.
Leaf physiognomic traits vary predictably along climatic and environmental gradients. The relationships between leaf physiognomy and climate have been investigated on different continents, but so far an investigation based on European vegetation has been missing. A grid data set (0.5 degrees x 0.5 degrees latitude/longitude) has been compiled in order to determine spatial patterns of leaf physiognomy across Europe. Based on distribution maps of native European hardwoods, synthetic chorologic flora lists were compiled for all grid cells. Every synthetic chorologic flora was characterised by 25 leaf physiognomic traits and correlated with 16 climatic parameters. Clear spatial patterns of leaf physiognomy have been observed, which are statistically significant related to certain, temperature-related climate parameters. Transfer functions for several climatic parameters have been established, based on the observed relationships. The study provides evidence that synthetically generated floras represent a powerful tool for analysing spatial patterns of leaf physiognomy and their relationships to climate. The transfer functions from the European data set indicate slightly different relationships of leaf physiognomy and environment compared with results obtained from other continents. 相似文献
10.
M. Fenner W. G. Lee J. Bastpw Wilson 《Biological journal of the Linnean Society. Linnean Society of London》1997,62(2):225-237
The biodiversity of floras has until recently been measured solely in terms of their species number or species density, with little regard to the breadth of phylogenetic diversity represented by the species. The latter is partly a function of the size of the flora, and partly of the pattern of distribution of the species into higher taxa. To determine whether floras differ in this respect, this study compares the frequency distribution of genus size in 20 island and regional floras. Certain floras (Cape Region, S.W. Australia, New Zealand, Hawaii) are found to have high concentrations of genera containing many species. Others are notably lacking in large genera (Java, Jamaica, Nepal, Niger), though this group tend to be family-rich. In floras with high endemism (Cape, New Zealand, Fiji, Jamaica, Hawaii), the level of endemism is consistently higher in larger genera. Possible reasons for the observed differences between floras are geographic and temporal isolation, level of habitat diversity, climatic history, volcanic, orogenic and tectonic events. Clusters of large genera may indicate recent speciation, possibly following the last glaciation. Genus size may be an important consideration when limited conservation resources have to be targetted to retain the maximum phylogenetic diversity in a threatened flora. 相似文献
11.
Mihai Emilian Popa 《古生物学报》2023,62(4):567-574
罗马尼亚白垩纪植物群以压型植物化石为代表, 其他植物化石类型则包括碎屑和搬运的类群, 并缺乏角质层和孢粉学记录。以压型为代表的白垩纪植物群主要分布在南喀尔巴阡山脉的几个盆地(包括Ha?eg、Rusca Montan?和Ruc?r盆地)、特兰西瓦尼亚(特兰西凡尼亚盆地)和多布罗吉亚(巴巴达格盆地), 在东喀尔巴提亚山脉也有少量分布。这些植物群的时代从Cenomanian到Maastrichtian, 其分类多样性包括蕨类植物(木贼类、真蕨类)、 裸子植物(松柏类)和被子植物(单子叶植物和双子叶植物)。从古植物地理学的角度来看, 罗马尼亚白垩纪植物群属于欧洲省Eurosinian地区, 分布在特提斯地区的北部框架上, 唯一的成煤植物群分布在Rusca Montan?盆地。 相似文献
12.
Aim To determine the relative contribution of species replacement and species richness differences to the emergence of beta‐diversity patterns. Innovation A novel method that disentangles all compositional differences (βcc, overall beta diversity) in its two components, species replacement (β‐3) and species richness differences (βrich) is proposed. The performance of the method was studied with ternary plots, which allow visualization of the influence of the relative proportions of shared and unique species of two sites over each metric. The method was also tested in different hypothetical gradients and with real datasets. The novel method was compared with a previous proposal based on the partitioning of overall compositional differences (βsor) in replacement (βsim) and nestedness (βnes). The linear response of βcc contrasts with the curvilinear response of βsor to linear gradients of dissimilarity. When two sites did not share any species, βsim was always 1 and β‐3 only reached 1 when the number of exclusive species of both sites was equal. β‐3 remained constant along gradients of richness differences with constant replacement, while βsim decreased. βrich had a linear response to a linear gradient of richness differences with constant species replacement, whereas βnes exhibited a hump‐shaped response. Moreover, βsim > βnes when clearly almost all species of one site were lost, whereas β‐3 < βrich in the same circumstances. Main conclusions The behaviour of the partition of βcc into β‐3 and βrich is consistent with the variation of replacement and richness differences. The partitioning of βsor into βsim and βnes overestimates the replacement component and underestimates richness differences. The novel methodology allows the discrimination of different causes of beta‐diversity patterns along latitudinal, biogeographic or ecological gradients, by estimating correctly the relative contributions of replacement and richness differences. 相似文献
13.
- Studies that analyse the structure of assemblages across relevant spatial scales can ascertain generalisable patterns and be used to guide efforts that allocate resources meant to conserve regional biodiversity. Beta diversity can shed light on the underlying factors that drive variation in assemblage structure including spatial and environmental influences. The purpose of this study was to address two questions: (1) Which is more important for the structuring of fish assemblages, spatial or environmental factors? (2) What is the dominant pattern underlying species turnover between fish assemblages, species addition (i.e. nestedness) or species replacement (i.e. spatial turnover)?
- We examined fish beta diversity in southeastern Oklahoma by sampling 65 wadeable stream reaches and measuring 30 environmental factors at each sampling location across the Muddy Boggy River drainage. Variation in fish assemblage structure was partitioned between environmental and spatial predictors using partial redundancy analysis. Overall species turnover was calculated and separated into its two additive components of spatial turnover and nestedness to determine which of these two accounted for the most turnover across the drainage.
- Spatial and environmental factors combined accounted for 25.5% of fish beta diversity. Environmental factors alone accounted for 20.1%, while spatial factors alone only accounted for 3.5% of the variation among assemblages.
- Nine environmental factors were significantly related to fish beta diversity: (1) elevation; (2) stream order; (3) stream width; (4) % riffle habitat; (5) water temperature; (6) conductivity; (7) turbidity; (8) % gravel substrate and (9) current velocity.
- Overall species turnover was driven mostly by spatial turnover rather than nestedness. This pattern was found to be the same across multiple spatial scales (entire drainage, sub‐drainages, mainstems) and despite several techniques used to extract turnover coefficients.
- These results suggest that fish assemblages—particularly in headwater streams—are structured by environmental filtering and that these assemblages tend to be compositionally distinct, rather than being nested derivatives of one another.
14.
Lara G. Melchior Denise de C. Rossa‐Feres Fernando R. da Silva 《Ecology and evolution》2017,7(7):2403-2413
15.
基于物种分布或群落组成的嵌套格局(嵌套分布格局)是岛屿生物地理学和群落生态学的重要前沿研究领域和核心问题之一。嵌套分布格局最初起源于岛屿物种组成的研究, 是指物种较贫乏岛屿中的物种是物种较丰富岛屿中的物种的一个适当子集的分布模式。深入了解嵌套分布格局及其影响机制对生物多样性保护具有重要意义, 并可用于指导管理工作。近40年来, 嵌套分布格局备受生态学家和保护生物学家的关注, 并且在分析方法、影响机制、生物多样性保护应用等方面都取得了一系列重要进展。本文通过对文献的系统检索和归纳总结, 从4个方面对嵌套分布格局的最新研究进展进行了综述: (1)发展历史及其研究现状; (2)分析方法, 包括各个嵌套指数和零模型的优点与局限; (3)影响机制及其检验方法; (4)在生物多样性保护与管理中的应用。最后, 我们对该领域进行了归纳总结并对以后的发展方向提出了针对性建议, 包括选择最适合的嵌套指数和零模型进行嵌套分析、同时对多种嵌套理论假说进行验证、开展更多关于功能嵌套和谱系嵌套的研究、推动嵌套分布格局与其他相关领域的融合。本文对于深入了解嵌套分布格局的前沿进展, 以及推动国内该领域的快速发展将有重要意义。 相似文献
16.
Mutualistic interactions between animals and plants vary over time and space based on the abundance of fruits or animals and seasonality. Little is known about this temporal dynamic and the influence of biotic and abiotic factors on the structure of interaction networks. We evaluated changes in the structure of network interactions between bats and fruits in relation to variations in rainfall. Our results suggest that fruit abundance is the main variable responsible for temporal changes in network attributes, such as network size, connectance, and number of interactions. In the same way, temperature positively affected the abundance of fruits and bats. An increase in temperature and alterations in rainfall patterns, due to human induced climate change, can cause changes in phenological patterns and fruit production, with negative consequences to biodiversity maintenance, ecological interactions, and ecosystem functioning. 相似文献
17.
内蒙古阿拉善地区分布着超过20万km2的典型戈壁生态系统, 且这些戈壁生态系统正遭受着持续性气候变暖与极端天气的影响。然而, 土壤、气候、空间变量等因子对阿拉善戈壁大尺度植物β多样性及其关键组分的相对影响还没有得到系统研究。本文通过对阿拉善典型戈壁生境的276个样方进行植物群落组成调查, 并结合气候、土壤等数据, 探讨了地理距离和环境因子对阿拉善戈壁区植物群落β多样性及其组分的影响。研究表明: (1)在阿拉善戈壁区, 随着地理距离的增加, 植物群落β多样性及物种周转组分显著增加, 而且β多样性主要源于物种周转组分, 物种嵌套组分的贡献非常有限; (2)偏Mantel分析显示环境因子和地理距离对β多样性及其物种周转组分均有显著的单独作用; 方差分解结果进一步表明, 环境因子和地理距离共同解释了植物β多样性及其物种周转组分10.84%-17.67% (Bray-Curtis)和15.47%-24.81% (Sørensen)的变异, 但环境因子可以单独解释更多的变异(6.62%-9.97% (Bray-Curtis)和8.98%-14.51% (Sørensen))。在众多环境因子中, 气温日较差、土壤含水量和地表砾石盖度对植物群落β多样性和物种周转组分的贡献更大。以上结果表明, 环境过滤、扩散限制以及其他未知过程可能共同影响阿拉善戈壁区植物群落β多样性格局, 其中环境过滤可能具有更大的影响。 相似文献
18.
Virginie Millien;Chengxiu Zhan;Yanxia Li;Jiang Wang;Yanping Wang; 《Global Ecology and Biogeography》2024,33(9):e13885
A nested pattern (nestedness) in species composition is a frequent signature of insular communities. However, it remains unclear whether the drivers of nestedness are consistent across multiple island systems. Here, we investigated the pattern and drivers of taxonomic, functional and phylogenetic nestedness in terrestrial mammal assemblages from 10 distinct island systems (archipelagos). 相似文献
19.
Sandra Navarro-Mayoral;Francisco Otero-Ferrer;Victoria Fernandez-Gonzalez;Néstor E. Bosch;Yolanda Fernández-Torquemada;Fiona Tomás;Jorge Terrados;Luis Miguel Ferrero Vicente;Yoana del Pilar-Ruso;Fernando Espino;Fernando Tuya; 《Ecology and evolution》2024,14(12):e70708
Identifying drivers that shape biodiversity across biogeographical regions is important to predict ecosystem responses to environmental changes. While β-diversity has been widely used to describe biodiversity patterns across space, the dynamic assembly of species over time has been comparatively overlooked. Insights from terrestrial and marine studies on temporal β-diversity has mostly considered environmental drivers, while the role of biotic mechanisms has been largely ignored. Here, we investigated patterns of temporal variation in β-diversity of seagrass-associated amphipods. We conducted a study in three biogeographical regions across a temperate to subtropical latitudinal gradient (approximately 2000 km, 13° of latitude in total). In each region, we randomly selected three Cymodocea nodosa meadows, totaling nine meadows sampled seasonally (i.e., four times per year) from 2016 to 2018. We partitioned temporal β-diversity into its turnover (i.e., species replacement) and nestedness (i.e., differences in species composition caused by species losses) components and addressed the relative influence of both temporal variation in habitat structure (i.e., biotic driver) and environmental conditions on the observed β-diversity patterns. Our study revealed high temporal β-diversity of amphipod assemblages across the three biogeographical regions, denoting significant fluctuations in species composition over time. We identified species turnover as the primary driver of temporal β-diversity, strongly linked to temporal variability in local habitat structure rather than to regional climatic drivers. Subtropical Atlantic meadows with high structural stability over time exhibited the largest turnover rates compared with temperate Mediterranean meadows, under lower structural stability, where nestedness was a more relevant component of temporal β-diversity. Our results highlight the crucial role of habitat stability in modulating temporal β-diversity patterns on animals associated with seagrasses, stressing the importance of monitoring variations in habitat structure over time for developing management plans and restoration actions in the context of diversity loss and fragmentation of ecosystems. 相似文献
20.
A full understanding of the origin and maintenance of β-diversity patterns in a region requires exploring the relationships of both taxonomic and phylogenetic β-diversity (TBD and PBD, respectively), and their respective turnover and nestedness components, with geographic and environmental distances. Here, we simultaneously investigated all these aspects of β-diversity for angiosperms in China. Specifically, we evaluated the relative importance of environmental filtering vs dispersal limitation processes in shaping β-diversity patterns. We found that TBD and PBD as quantified using a moving window approach decreased towards higher latitudes across the whole of China, and their turnover components were correlated with latitude more strongly than their nestedness components. When quantifying β-diversity as pairwise distances, geographic and climatic distances across China together explained 60 and 53% of the variation in TBD and PBD, respectively. After the variation in β-diversity explained by climatic distance was accounted for, geographic distance independently explained about 23 and 12% of the variation in TBD and PBD, respectively, across China. Overall, our results suggest that environmental filtering based on climatic tolerance conserved across lineages is the main force shaping β-diversity patterns for angiosperms in China. 相似文献