Large Niche Overlap Research Articles

Niche Dynamics Below the Species Level: Evidence from Evaluating Niche Shifts within Quercus aquifolioides

The role of ecological niches in lineage diversification has been the subject of long-standing interest of ecologists and evolutionary biologists. Specific responses to climate change can arise below the species level, resulting in differentiated adaptation or movement patterns within a given species. Thus, the urgent need to model potential responses to ongoing climate changes among genetically distinct populations within a species is increasingly recognized. In this study, we utilize the information of intraspecific variation within Quercus aquifolioides as a priori, and then focus on the potential distribution ranges and niche dynamics of its three intraspecific lineages (WSP, HDM, and Tibet) under current environmental conditions via ecological niche models (ENMs) and PCA-env ordination method, respectively. Our results indicated that the three lineages have occupied differentiated climatic niches. Although the three lineages have distinctly adaptive strategies for homogeneous environmental conditions, some lineages had sympatric projecting areas. The PCA-env demonstrated that the lineage pair WSP vs. HDM had the largest niche overlap while Tibet vs. HDM showed the smallest one. Moreover, the hypothesis of the niche was indistinguishable within the three lineages rejected, indicating the presence of niche divergence rather than niche conservatism below the species level. Our findings highlight the potential of modeling intraspecific responses to climate change and provide insights into lineage diversification within Q. aquifolioides, permitting the exploration of the information determined by niche evaluations and comparisons to understand plant diversification processes below the species level in biodiversity hotspots.

广西大石围天坑群草本植物多样性及其生态位变化规律

PDF HTML阅读 XML下载 导出引用 引用提醒 广西大石围天坑群草本植物多样性及其生态位变化规律 DOI: 10.5846/stxb202204251137 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（31960047）；珍稀濒危动植物生态与环境保护教育部重点实验室研究基金（ERESEP2019Z04）；广西重点研发计划项目（桂科AB21220057）；广西漓江流域景观资源保育与可持续利用重点实验室研究基金（LRCSU21Z0101） Diversity and niche characteristics of herbaceous plants in Dashiwei Tiankeng Group, Guangxi 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:研究不同发育时期天坑草本植物的多样性，能更好的理解草本层对天坑环境变化的响应机制。以广西大石围天坑群中不同发育时期天坑（初期、中期和后期）为研究对象，采用空间代替时间的方法，分析不同发育时期天坑草本植物多样性和生态位变化规律。结果表明：（1）广西大石围天坑群调查样地共记录到草本植物34科71属98种，以鳞毛蕨科、荨麻科、凤尾蕨科、菊科和禾本科为主。（2）后期天坑草本植物的Pielou's指数和Shannon-Wiener指数均显著高于初期天坑（P<0.05），表明随着天坑发育到后期，草本层物种数逐渐增多，物种分布更为均匀。（3）随着天坑的发育，草本层喜阴植物重要值下降，喜阳、半阴植物重要值上升，喜阳植物逐渐取代喜阴植物在群落中占据优势地位，草本层将经历喜阴植物-喜阴、半阴植物-喜阳植物的三个生态型转变过程。（4）各发育时期优势草本生态位相似性比例和生态位重叠平均值均<0.5，表明天坑不同发育时期对草本植物的生态位影响较小，各时期草本层总体呈现生态分化明显、种间竞争较弱的特点。（5）各发育时期优势草本生态位重叠值大、相对高度差小的种对数中，不同生态习性的种对数占比不同，中期天坑种对数远高于初期和后期天坑，表明不同发育时期中不同生态习性的草本对光能的竞争程度存在差异，中期天坑草本植物对光能竞争最为激烈。综上所述，广西大石围天坑群各发育时期草本层生态分化明显、群落结构稳定，后期天坑草本多样性最为丰富。 Abstract:Studying the diversity and niche characteristics of herbaceous plants in different developmental stages of Tiankeng can better understand the response mechanism of the herbaceous layer to the environmental changes and provide an important scientific basis for the protection of ecological environment and biodiversity resources in Tiankeng. In this study, the herbaceous in different developmental stages of Tiankeng (the earlier stage, middle stage, and later stage) were selected as the objects. We used the method of space instead of time to establish 168 herbaceous quadrates in Dashiwei Tiankeng Group, Guangxi and carried out investigations. Shannon-Wiener index, Simpson index, Pielou's index and Patrick index were used to evaluate the herb diversity at different developmental stages of the Tiankeng. The ecological niche characteristics (niche width and niche overlap) of main species in the herb layer of the different developmental stages of Tiankeng were calculated. The results showed that:(1) a total of 98 species of herbaceous plants belonging to 71 genera and 34 families were recorded in Dashiwei Tiankeng Group, Guangxi. The principal families were Dryopteridaceae, Urticaceae, Pteridaceae, Asteraceae and Poaceae. (2) Pielou's index and Shannon-Wienner index of herbs in the later development stage of Tiankeng were significantly higher than those in the earlier development stage of Tiankeng (P<0.05), indicating that with the Tiankeng developed to the later stage, the number of species in the herb layer increased and the species distribution pattern was steady. (3) With the development of Tiankeng, the importance value of sciophiles in herb layer decreased, while the importance value of heliophiles and semishade increased and the dominance was prevalent in heliophiles than sciophiles. The herb layer would go through three ecotype transition processes of sciophiles-sciophiles and semishade-heliophiles. (4) The average value of niche similarity and niche overlap of dominant herbs at each developmental stage of Tiankeng were lower than 0.5, indicating that different developmental stages of Tiankeng had a slight impact on the niche of herbs. The herbaceous layer had obviously ecological differentiation and weakly inter-specific competition. (5) In the species pairs of dominant herbs large niche overlap and small relative height at each development stage, the species pairs of different ecological habits accounted for different proportions. The species pairs of the middle development stage of Tiankeng was much higher than that of earlier and later development stages of Tiankeng. The results showed that herbaceous plants with different ecological habits at different development stages had different competition degrees for light energy. The herbs in the middle development stage of Tiankeng had the fierce competition for light. In a word, the herb layer of Dashiwei Tiankeng Group in Guangxi was obviously differentiated, the community structure was relatively stable, and the species diversity of the later development stage of Tiankeng in herb layer was rich. 参考文献 相似文献 引证文献

Niche and interspecific association of dominant tree species in Michelia odora community

In order to understand the interspecific and ecological relationships of Michelia odora (extremely small population) community and strengthen the protection of wild M. odora resources in Junzifeng Nature Reserve, we studied the niche characteristics and interspecific associations of dominant tree species. The results showed that M. odora, Machilus chekiangensis, Schima superba, and Alniphyllum fortunei had obvious niche breadth advantages, which were the constructive species of the community. Among the 190 groups of species pairs among the 20 dominant tree species, 50.5% of species pairs had niche overlap value greater than 0.5. The degree of ecological niche differentiation among species was general. M. odora had large niche overlap with other 19 species, indicating a competitive risk when resources were insufficient. The overall associations of dominant tree species were significantly positive, indicating the community was at the late stage of relatively stable succession. The results ofχ2 test, asso-ciation coefficient, and Pearson correlation coefficient showed that all the significance ratios of interspecific association were lower, and that the independence among species was relatively strong. There was a positive correlation between interspecific association and niche overlap. The M. odora community was relatively mature, with full utilization of resources and stable interspecific relationship. To promote the rejuvenation and create a good habitat of M. odora population, the population size with large overlap with M. odora niche and significant negative association could be appropriately limited, while that with positive interaction could be increased.

Environmental filtering rather than dispersal limitation dominated plant community assembly in the Zoige Plateau.

Identifying the mechanisms that underlie the assembly of plant communities is critical to the conservation of terrestrial biodiversity. However, it is seldom measured or quantified how much deterministic versus stochastic processes contribute to community assembly in alpine meadows. Here, we measured the decay in community similarity with spatial and environmental distance in the Zoige Plateau. Furthermore, we used redundancy analysis (RDA) to divide the variations in the relative abundance of plant families into four components to assess the effects of environmental and spatial. Species assemblage similarity liner declined with geographical distance (p < .001, R 2 = .6388), and it decreased significantly with increasing distance of total phosphorus (TP), alkali‐hydrolyzable nitrogen (AN), available potassium (AK), nitrate nitrogen (NO3 +–N), and ammonia nitrogen (NH4 +–N). Environmental and spatial variables jointly explained a large proportion (55.2%) of the variation in the relative abundance of plant families. Environmental variables accounted for 13.1% of the total variation, whereas spatial variables accounted for 11.4%, perhaps due to the pronounced abiotic gradients in the alpine areas. Our study highlights the mechanism of plant community assembly in the alpine ecosystem, where environmental filtering plays a more important role than dispersal limitation. In addition, a reasonably controlled abundance of Compositae (the family with the highest niche breadth and large niche overlap value with Gramineae and Cyperaceae) was expected to maintain sustainable development in pastoral production. These results suggest that management measures should be developed with the goal of improving or maintaining suitable local environmental conditions.

Retrospective stable isotopes of vertebrae reveal sexual ontogenetic patterns and trophic ecology in oceanic whitetip shark, Carcharhinus longimanus.

There is a common phenomenon in nature whereby some animals have differences in their ontogenetic changes in dietary preferences between sexes, especially apex predators. These reflect changes in the needs of development during their lifetimes. Apex predators potentially have diverse dietary niches and a large impact on the trophic dynamics within ecosystems. However, the difference in life history between males and females often leads to increased difficulty in management and conservation. In this study, 25 oceanic whitetip sharks, Carcharhinus longimanus, were collected from the central and eastern tropical Pacific. Retrospective stable isotope analysis of vertebrae was used to evaluate the potential ontogenetic differences in feeding habits and niche width between sexes. Results showed that C. longimanus had a wide range of δ13C values (−18.1 to −12.3‰) and δ15N values (8.9–14.8‰). However, males and females had similar trophic positions with large niche overlap at similar growth stages. Both sexes had increasing δ13C values but relatively constant δ15N values along the vertebrae. These results indicated that male and female C. longimanus may share similar feeding strategies and movement patterns. The results presented in this study enhance our understanding of sexual ontogenetic patterns and ecological role of C. longimanus and highlighted the applicability of vertebrae for characterizing shark life‐history traits.

Identifying niche and fitness dissimilarities in invaded marine macroalgal canopies within the context of contemporary coexistence theory

Contemporary coexistence theory provides a framework for predicting invasiveness and impact of Invasive Non-Native Species (INNS) by incorporating differences in niche and fitness between INNS and co-occurring native species. The widespread invasive kelp Undaria pinnatifida is considered a high-risk INNS, although a robust evidence base regarding its invasiveness and impact is lacking in many regions. Invaded macroalgal canopies at nine coastal sites in the southwest UK were studied over three years to discern whether Undaria is coexisting or competing with native canopy-forming species across different habitat types. Spatial, temporal and depth-related trends in species distributions and abundance were recorded within intertidal and subtidal rocky reef as well as on marina pontoons. A primary succession experiment also examined competitive interactions between species. In rocky reef habitats, Undaria had lower fitness compared to long-lived native perennials, but was able to coexist due to niche dissimilarity between species. In contrast, Undaria was likely to be competing with short-lived native annuals on rocky reef due to large niche overlap and similar fitness. In marina habitats, Undaria dominated over all other canopy formers due to low niche diversification and higher fitness. Generalisations on INNS impact cannot be made across habitats or species, without considering many abiotic factors and biotic interactions.

Diet composition of the lizard Podarcis lilfordi (Lacertidae) on 2 small islands: an individual-resource network approach.

Despite it is widely accepted that intrapopulation variation is fundamental to ecological and evolutionary processes, this level of information has only recently been included into network analysis of species/population interactions. When done, it has revealed non-random patterns in the distribution of trophic resources. Nestedness in resource use among individuals is the most recurrent observed pattern, often accompanied by an absence of modularity, but no previous studies examine bipartite modularity. We use network analysis to describe the diet composition of the Balearic endemic lizard Podarcis lilfordi in 2 islets at population and individual levels, based on the occurrence of food items in fecal samples. Our objectives are to 1) compare niche structure at both levels, 2) characterize niche partition using nestedness and modularity, and 3) assess how size, sex, season, and spatial location influence niche structure. At population-level niche width was wide, but narrow at the level of the individual. Both islet networks were nested, indicating similar ranking of the food preferences among individuals, but also modular, which was partially explained by seasonality. Sex and body size did not notably affect diet composition. Large niche overlap and therefore possibly relaxed competition were observed among females in one of the islets and during spring on both islets. Likewise, higher modularity in autumn suggests that higher competition could lead to specialization in both populations, because resources are usually scarce in this season. The absence of spatial location influence on niche might respond to fine-grained spatio-temporally distribution of food resources. Behavioral traits, not included in this study, could also influence resource partitioning.

Analysing the ecological niche of water quality of key species in the aquatic ecosystem in Jinan City

The construction of hydrogeological cities in China has attracted attention from researchers worldwide. This study surveyed the major urban hydroecological river channels and selected 59 stations for hydroecological field sampling. The Ecopath model was used to screen for key river species, and niche analysis was performed to study the niche breadth and overlap between the key species and water quality factors. Sixteen key fish species were screened out; Pseudorasbora parva had the highest niche breadth (2.952). Of the 16 screened key species, Carassius auratus had the largest niche overlap (11.977). Seven key zooplankton species were screened out. Phryganella nidulus had the highest niche breadth (2.070). Of the seven screened key species, P. hemisphaerica had the largest niche overlap (9.065). Of the nine screened key species, Bithynia fuchsiana had the largest niche overlap. These findings provide a reliable theoretical basis for ecological restoration, and serve as a methodological reference for sustainable water resources management.

基于两个不同资源轴上苔藓植物生态位分析

PDF HTML阅读 XML下载 导出引用 引用提醒 基于两个不同资源轴上苔藓植物生态位分析 DOI: 10.5846/stxb201608101638 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 河南省科技攻关（132102110133）；河南省教育厅科学技术研究重点项目（14A180013） Ecological niche of bryophytes based on two resource axes 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:分别以群丛类型和生长基质类型（包括树生、石生、土生）作为资源轴，对小秦岭56个样方中苔藓植物的生态位特征进行分析和对比。结果表明：（1）两种资源轴上苔藓物种的生态位特征存在一定差异，不同资源轴上，苔藓物种生态位宽度排序发生一定改变。两种资源轴上，青藓属（Brachythecium）均具有较大的生态位宽度，而酸土藓属（Oxystegus）和叶苔属（Jungermania）在不同资源轴上生态位宽度差异较大。（2）对比两种资源轴上的生态位重叠值，生长基质类型明显高于群丛类型；在不同资源轴上，个别物种生态位重叠值排序还会发生明显改变。树平藓属（Homaliodendron）与金灰藓属（Pylaisiella）在两种资源轴上表现出完全相反结果。（3）与维管植物相似，生态位宽度较大的苔藓物种生态位重叠值高，生态位宽度小的苔藓物种也会有较大生态位重叠。 Abstract:Bryophytes, which are relatively primitive species among higher plants, are an important component of biodiversity. The ecological adaptability of species varies based on resource space. This study was conducted in the small Xiaoqinling Mountains Nature Reserve, which was located in Lingbao in Western Henan Province. This location was rich in plant resources; the geographical coordinates are 34°23'-34°31'N, 110°23'-110°44'E. Using stratified sampling and a coastal wave height setting, fifty-six 20 m × 20 m representative sample plots were selected, and the trees, shrubs, herbs, and bryophytes were surveyed and sampled. The multiple regression tree method was used for the 56 plots. Elevation, slope, and aspect were independent variables, and 405 vascular plants in the 56 plots were used to determine the importance value of these dependent variables for community classification. The 56 sample plots were divided into five cluster types and defined as different resource bases, according to the determination of bryophyte epiphytic substrates, which were divided into trees and rocks characteristic of different resource niches. In two different resource axes, 15 types of importance values were chosen. The largest included the order Jungermanniales. Mosses included both acrocarpous and pleurocarpous types. The niche breadth and overlap values of the 15 selected groups were determined using the Shannon-Wiener niche index and Levins niche overlap value. The effects of association between substrate types (trees, rock, and soil) as resource axes on the niche characteristics of bryophytes were examined and compared among the 56 sites. The results showed the following: (1) The two resource axes of niche characteristics of bryophytes differed. On different resource axes, breadth varied among different bryophyte species. In particular, the breadth of Brachythecium was greater. The breadths of Oxystegus and Jungermania in the two types of resource axes differed. In the two resource axes, Brachythecium had a larger niche breadth, ecological adaptability, and environmental utilization ability, whereas the niche width of Homaliodendron was smaller, narrower, and exhibited weaker ecological adaptability. Oxystegus and Jungermania niche widths differed between the resource axes. (2) The niche overlap values of the substrate for the two resource axes were significantly higher than those of association types. The niche overlap order of individual species on different resource axes also differed. Homaliodendron and Pylaisiella showed the opposite results. (3) Similar to that observed in vascular plants, in bryophyte species, niche overlap was high with large niche breadth. Bryophyte species with small niche breadth could also exhibit large niche overlap. For example, Brachythecium had a large niche breadth, whereas the other species had large niche overlap values. However, Oxystegus and Fissidens exhibited niche widths that were small, although they still exhibited large niche overlap values, thereby demonstrating that a certain degree of similarity existed in the use of both resources. 参考文献 相似文献 引证文献

Environmental niche variation and evolutionary diversification of the Brachypodium distachyon grass complex species in their native circum-Mediterranean range.

• We conducted environmental niche modeling (ENM) of the Brachypodium distachyon s.l. complex, a model group of two diploid annual grasses (B. distachyon, B. stacei) and their derived allotetraploid (B. hybridum), native to the circum-Mediterranean region. We (1) investigated the ENMs of the three species in their native range based on present and past climate data; (2) identified potential overlapping niches of the diploids and their hybrid across four Quaternary windows; (3) tested whether speciation was associated with niche divergence/conservatism in the complex species; and (4) tested for the potential of the polyploid outperforming the diploids in the native range.• Geo-referenced data, altitude, and 19 climatic variables were used to construct the ENMs. We used paleoclimate niche models to trace the potential existence of ancestral gene flow among the hybridizing species of the complex.• Brachypodium distachyon grows in higher, cooler, and wetter places, B. stacei in lower, warmer, and drier places, and B. hybridum in places with intermediate climatic features. Brachypodium hybridum had the largest niche overlap with its parent niches, but a similar distribution range and niche breadth.• Each species had a unique environmental niche though there were multiple niche overlapping areas for the diploids across time, suggesting the potential existence of several hybrid zones during the Pleistocene and the Holocene. No evidence of niche divergence was found, suggesting that species diversification was not driven by ecological speciation but by evolutionary history, though it could be associated to distinct environmental adaptations.

Tropical Forests Are Non-Equilibrium Ecosystems Governed by Interspecific Competition Based on Universal 1/6 Niche Width

Tropical forests are mega-diverse ecosystems that display complex and non-equilibrium dynamics. However, theoretical approaches have largely focused on explaining steady-state behaviour and fitting snapshots of data. Here we show that local and niche interspecific competition can realistically and parsimoniously explain the observed non-equilibrium regime of permanent plots of nine tropical forests, in eight different countries. Our spatially-explicit model, besides predicting with accuracy the main biodiversity metrics for these plots, can also reproduce their dynamics. A central finding is that tropical tree species have a universal niche width of approximately 1/6 of the niche axis that echoes the observed widespread convergence in their functional traits enabling them to exploit similar resources and to coexist despite of having large niche overlap. This niche width yields an average ratio of 0.25 between interspecific and intraspecific competition that corresponds to an intermediate value between the extreme claims of the neutral model and the classical niche-based model of community assembly (where interspecific competition is dominant). In addition, our model can explain and yield observed spatial patterns that classical niche-based and neutral theories cannot.

Niche comparisons: toward a new approach for analysing competition and organizational performance in the international construction market

Over the past few decades, studies on competition and organizational performance in the international construction market have been prolific. Construction companies are founded, then grow, compete, evolve, and die in the international landscape, a common process from an ecological perspective. However, few studies have considered the international construction market from this perspective. Using niche theory, which was initially populated in the field of natural bio-ecology and then introduced to business management and economics, a NW/O-L (niche width/overlap and location) framework is established in this study. With this framework, the niche evolution of the top 225 international contractors is explored along two dimensions—product and geography. The effects of a proper niche on an international construction company’s performance are also investigated using the cluster analysis method. It was discovered that, despite fluctuations over time, the contractor’s niche is highly related to its performance in the international construction market. The most appropriate niche for international construction contractors is a wide niche width, with a small niche overlap and with its location near to the market centre with comparatively more market resources. However, only a few contractors can survive in this niche, as the majority of contractors are in a narrow niche width, with a comparatively large niche overlap and far from the market centre. Contractors which do not fit either of these two niches have proved to be poor performers in this study.

Niche Separation by Mink and River Otters: Coexistence in a Marine Environment

We studied habitat selection and niche separation by mink (Mustela vison) and sympatric river otters (Lutra canadensis) living in a coastal environment in Prince William Sound, Alaska, during summer 1991. We hypothesized that exposure to wave action, depth of tidal zone, substrate composition, and availability of cover were important habitat variables in selection of sites by mink at the terrestrial - marine interface. We also hypothesized that because of high resource abundance, little resource partitioning would occur between mink and river otters in the marine environment, leading to a large niche overlap. We employed step-wise logistic regression to develop a model separating feeding sites of mink, based on trails and latrines, from random sites. This model identified vegetated slope, tidal slope, overstory (old-growth forest), under-story (brush), small rocks, and exposure to wave action as the variables characterizing sites selected by mink. Mink selected (use > availability) shallow vegetated slopes and tidal slopes. Mink also selected sites that were more protected from wave action and with more overstory cover, but avoided (use < availability) beaches with small rocks as the main substrate, which is likely to be correlated with low availability of food. Analysis of niche overlap identified exposure and overstory as two variables that differ significantly between these two mustelids. Niche overlap including all habitat variables was 48%. Removal of exposure and overstory from this calculation resulted in 78.5% overlap. River otters selected sites with high exposure to wave action, whereas mink selected sites with low and medium exposure. Otters selected sites with high overstory cover, whereas mink showed less preference for such sites. Therefore, we have recorded niche separation in a marine environment, but were unable to attribute it to competition. Moreover, pronounced resource partitioning occurred even when food was abundant.

Effects of predator-specific defence on community complexity

Some properties of community structure are explored using co-evolutionary theory. We consider mathematical models of food webs in which all species in a community adopt foraging behaviours and antipredator behaviours that maximize individual fitness. If the antipredator behaviour of a prey is effective against all its enemies, the number of prey—predator links in a food web must be less than the sum of the numbers of prey and predator species. However, if an increase in a prey's attention to one type of predator decreases its attention to another type of predator, there may be no limit on the number of predator species using a common set of prey species. Predator-specific defence allows a much more complex community structure than non-specific defence. Predator-specific defence more frequently allows a large niche overlap between predators than does non-specific defence. The high connectivity of some fish communities in Lake Tanganyika may be an example of this phenomenon.