两种绣线菊低温锻炼与脱锻炼处理对蛋白质表达的影响

通过2维双向电泳法,研究抗寒能力与光合能力不同的金山绣线菊与华北绣线菊,低温锻炼处理对蛋白质表达所产生的影响。结果表明,低温锻炼处理对2种绣线菊蛋白质表达的影响显著不同,在低温锻炼与脱锻炼处理中,金山绣线菊产生低温诱导特异蛋白,华北绣线菊没有低温诱导特异蛋白表达;蛋白质双向电泳图谱分析表明,华北绣线菊与金山绣线菊经过低温锻炼后发生蛋白质差异表达,经质谱鉴定其中的3种显著差异表达的蛋白质分别为2种未知新蛋白,2种未知蛋白的部分氨基酸序列分别为VSHLAGFSSNNPK、LKADKPTLLSEAK;DPNDHPNPFTVK、DGNGFFLYLLDPDSSK、NGDGMFLYLLDGLESK,另一种差异蛋白为抗坏血酸过氧化物酶;低温锻炼处理使绣线菊中与光合作用密切相关的蛋白质抗坏血酸过氧化物酶发生了显著的变化。     

海南岛东寨港几种红树植物种间生态位研究

采用3种常见的生态位宽度和生态位重叠计测公式,以外来种无瓣海桑扩散区的秋茄+桐花树群落演替系列作为资源轴,定量计测了几种红树植物的生态位宽度和重叠值.结果表明,各树种生态位宽度值排序为桐花树(3.8357)＞秋茄(3.3421)＞木榄(3.3180)＞白骨壤(3.0975)＞无瓣海桑(2.9137)＞海桑(2.5724)＞角果木(1.8523)＞红海榄(1.6897)＞海莲(1.0000),很好地表征了其生态适应性和分布幅度.各树种重叠值中,以秋茄、桐花树、木榄、白骨壤之间的生态位重叠较大,表明其间存在较强的资源利用性竞争.无瓣海桑生态位宽度处于中等程度,与中低潮滩红树植物海桑、桐花树、秋茄和白骨壤的重叠值相对较高,与红海榄、木榄有中度重叠,与角果木有少量重叠,与海莲完全没有重叠.     

Patterns of coexistence in sexual and asexual species of Cnemidophorus lizards

Summary The lizard genus Cnemidophorus (family Teiidae) contains sexual as well as parthenogenetic species. The theoretical two-fold fitness advantage of asexuality does not translate into any obvious distributional or numerical superiority of the parthenogenic species in the southwestern US and northern Mexico where their ranges overlap. I tested the prediction that the genetically diverse sexual species should have a higher between-individual niche width than a similar sympatric asexual species by studying the prey in stomach contents of sympatric and allopatric populations of C. tigris (sexual) and C. sonorae (asexual) in southern Arizona. The expectation proved true for niche breadths based on both prey length and prey taxa categories. The within-individual component of niche breadth was not different between species. Meaningful comparisons between species in sympatry and allopatry are confounded by the uncontrolled differences in the availability and diversity of food items between sites. Before the generality of these results can be assessed the study should be repeated in other areas where sexual and asexual species are syntopic and of similar body size.     

濒危植物百花山葡萄群落物种生态位特征与种间联结研究

以北京市Ⅱ级重点保护野生植物百花山葡萄(Vitis baihuashanensis M.S.Kang et D.Z.Lu)为研究对象,通过对其野生个体所在群落和人工扩繁个体所在群落进行样方调查,定量分析百花山葡萄自然群落的生态位特征和种间联结关系,对比人工群落的相关情况,探讨其濒危原因。结果显示:百花山葡萄自然群落总体呈正相关,物种正负关联比小于1,仍在向稳定群落发育;由于高大乔木和上层优势灌木截获了大量光照,以及高生态位重叠物种小花溲疏(Deutzia parviflora Bge.)、牛叠肚(Rubus crataegifolius Bge.)、短尾铁线莲(Clematis brevicaudata DC.)、五味子(Schisandra chinensis(Turcz.)Baill.)对各类资源的夺取,使百花山葡萄的营养生长受到明显限制。人工群落总体呈正相关,主要物种正负关联比大于1,目前处于相对较稳定状态;该群落缺乏高大乔木,光照充足,百花山葡萄与圆柏(Sabina chinensis(L.)Ant.)幼树等优势灌木呈不显著正相关,所受竞争压力相对较小,植株已进入生殖生长阶段。建议加强对百花山葡萄自然群落的人工抚育,适当疏枝、疏灌、疏藤,提高和改善百花山葡萄的光照条件,降低其他物种的资源竞争力度,以提高其在群落内的竞争能力,提升物种保护成效。     

Ecological correlates of species differences in the Lake Tanganyika crab radiation

The endemic crabs of Lake Tanganyika include a phenotypically diverse clade that exhibits recent divergence and low phylogenetic species resolution. There are indications that ecological niche segregation has played a prominent role in the divergence of this clade. We used habitat surveys, gut content analyses and stable isotope analyses to test the extent to which morphological species are ecologically different. Our data show some interspecific segregation in depth, substrate type and mean stable isotope signatures. At the same time, a considerable level of ecological niche overlap is evident among species of Platythelphusa that coexist in rocky littoral habitats. We consider these results in the framework of adaptive radiation theory, and we discuss general ramifications for the maintenance of species diversity in Lake Tanganyika.     

Threshold facilitations of interacting species

The dynamics of species interactions are of central importance for the understanding of ecological coexistence, community structure and the effects of biological invasions. Using bark beetles that colonize the same habitat as an example, we explore species interactions in a resource-based model system with positive feedback between insect abundance and resource availability. The net interspecies interaction was found to be highly dynamic and may alternate in time between competition and mutualism. When both bark beetle species were able to kill trees (“aggressive”), our simulations showed strong facilitations between beetle species. This may lead to escape from control by competition, and increase the frequency of outbreaks of tree-killing. The frequency of net positive interactions varied with interaction strengths and the relative aggressiveness of the species and was highest when both species were strongly aggressive; which predicts disastrous outbreaks if, e.g., the European spruce bark beetle Ips typographus and the North American spruce beetle Dendroctonus rufipennis should become interacting species due to introductions. In imbalanced pairs, the relatively less aggressive species was facilitated more often than the aggressive species. Net positive interactions did not occur for strongly inferior species, but their survival was an increasing function of interaction strength with aggressive species and availability of resources. The benefits for the inferior species in the model are consistent with the structure of one aggressive and several less aggressive or non-aggressive species, which is common in bark beetle communities in many parts of the world.     

A comparison of realised niche relations of species in New Zealand and Britain

Summary Many plant species prominent in the native vegetation of the dry shingle banks at Dungeness (Britain) are also prominent as exotics in the dry Upper Clutha catchment (New Zealand). To examine the realised niche relations of these species, vegetation was sampled in the two areas. Inverse classification and ordination were used to determine the relative beta niches of the species in the two areas. There was little agreement; it seems that the exotic species in the Upper Clutha were pre-adapted to different niches from those in their native range.     

Idiosyncratic soil-tree species associations and their relationships with drought in a monodominant Amazon forest

Monodominant forests are characterized by the strong influence of a single species on the structure and diversity of the community. In the tropics, monodominant forests are rare exceptions within the generally highly diverse tropical forest biome. Some studies have shown that tree monodominance may be a transient state caused by successional and demographic variation among species over time. Working in a Brosimum rubescens Taub. (Moraceae) monodominant forest at the southern edge of Amazonia, we tested the hypotheses that local-scale variation in intra- and interspecific spatial patterns of dominant tree species is affected by i) demographic rates of recruitment and mortality following severe droughts, ii) local variation in edaphic properties, and iii) occupation of species in the vertical layer of the forest. We quantified intra- and interspecific spatial patterns and edaphic associations of the five most abundant species using aggregation and association distance indices, and examined changes over time. We found some support for all hypotheses. Thus, intra- and interspecific spatial patterns of most species varied over time, principally after severe drought, emphasizing species-level variability and their interactions in sensitivity to this disturbance, even as B. rubescens monodominance was maintained. While positive and negative spatial associations with edaphic properties provide evidence of habitat specialization, the absence of negative spatial associations of B. rubescens with edaphic properties indicates that this species experiences little environmental restriction, and this may be one of the factors that explain its monodominance. Spatial repulsion and attraction between species in the same and in different vertical layers, respectively, indicates niche overlap and differentiation, while changes over time indicate that the relationships between species are dynamic and affected by drought disturbance.     

Plant community structure,connectance, niche limitation and species guilds within a dune slack grassland

Species phytomass in 40 mm×40 mm quadrats was used to examine community structure in four homogeneous areas of vegetation in sand dune slacks. There were from 9 to 16 common species in the samples, and most parameters of community structure were found to relate consistently to species number. We used covariance between all species at increasing dimensions of aggregations of quadrats to suggest that sociological interaction between species existed at scales of around 200 mm diameter. Generalised variance was of no help in this enquiry. We show that a connectance estimation arrived at from these parameters is, although a real feature of the analysis, apparently unrelated to connectance as understood in the food web literature. There is strong evidence that guild structure, sociological interaction and niche limitation increase with increasing number of species present, so that most diverse assemblage can be said to have a definite community structure.     

Interspecific competitive interactions between pairs of fungal species in natural substrates

The role of interspecific competition in fungal communities in natural substrates is poorly understood because fungi do not form easily definable populations. A new approach to investigating fungal competition, using natural substrates containing a range of known biomass concentrations of each of two species, is described. Relative competitive success of each species is assessed over time in terms of propagule production and substrate colonisation by each species. In an agricultural soil Mucor hiemalis usually out-competed Trichoderma harzianum. After 27 days, the success of both species in the mixtures was independent of the initial biomass concentration of either species, although the success of T. harzianum in these mixtures was substantially inhibited relative to the T. harzianum monocultures. In a forest soil, T. polysporum maintained a competitive advantage over M. hiemalis, and induced M. hiemalis to produce propagules rather than mycelia. Coexistence of both species always occurred in both experiments, and in the forest soil experiment the two-species mixtures all contained a higher total microbial biomass than the monocultures of either species by day 47, suggesting some niche differentiation.     

Commonness of Amazonian palm (Arecaceae) species: Cross-scale links and potential determinants

The mechanisms that cause variation in commonness (abundances and range sizes) of species remain debated in ecology, and a repeatedly observed pattern is the positive relation between local abundances and larger scale range sizes. We used the Amazonian palm species (Arecaceae) to investigate the dependence between and potential determinants of commonness across three (local, landscape, continental) spatial scales. Commonness at the smaller scales (local abundance, landscape frequency) was estimated using data from 57 transects (5 × 500 m) in primary, non-inundated (terra firme) rainforest in a western Amazonian landscape, while commonness at the largest scale (continental range size) was estimated from digitized distribution maps. Landscape frequency was positively related to both local abundance and continental range size, which, however, were not related to each other. Landscape frequency was positively related to topographic niche breadth. Stem height correlated with continental range size and was the only species life-history trait related to any commonness measure. Distance from the study area to a species' range centre did not influence any of the commonness measures. The factors determining commonness in the Amazonian palm flora appear to be scale-dependent, with the unrelated local scale abundance and continental range size probably being controlled by different driving factors. Interestingly, commonness at the intermediate, landscape scale seems linked to both the smaller and the larger scale. Our results point towards topographic niche breadth at the smaller scales and stem height, possibly reflecting species' dispersal potential, at the continental scale as important determinants of commonness.     

Interspecific competition between two species of the bean weevil

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Contributions from the Entomological Laboratory, Kyoto University, No. 110.     

Linking nitrogen partitioning and species abundance to invasion resistance in the Great Basin

Resource partitioning has been suggested as an important mechanism of invasion resistance. The relative importance of resource partitioning for invasion resistance, however, may depend on how species abundance is distributed in the plant community. This study had two objectives. First, we quantified the degree to which one resource, nitrogen (N), is partitioned by time, depth and chemical form among coexisting species from different functional groups by injecting ¹⁵N into soils around the study species three times during the growing season, at two soil depths and as two chemical forms. A watering treatment also was applied to evaluate the impact of soil water content on N partitioning. Second, we examined the degree to which native functional groups contributed to invasion resistance by seeding a non-native annual grass into plots where bunchgrasses, perennial forbs or annual forbs had been removed. Bunchgrasses and forbs differed in timing, depth and chemical form of N capture, and these patterns of N partitioning were not affected by soil water content. However, when we incorporated abundance (biomass) with these relative measures of N capture to determine N sequestration by the community there was no evidence suggesting that functional groups partitioned different soil N pools. Instead, dominant bunchgrasses acquired the most N from all soil N pools. Consistent with these findings we also found that bunchgrasses were the only functional group that inhibited annual grass establishment. At natural levels of species abundance, N partitioning may facilitate coexistence but may not necessarily contribute to N sequestration and invasion resistance by the plant community. This suggests that a general mechanism of invasion resistance may not be expected across systems. Instead, the key mechanism of invasion resistance within a system may depend on trait variation among coexisting species and on how species abundance is distributed in the system.     

Limitation to plant species coexistence at a point: a study in a New Zealand lawn

Abstract. Limitation in the number of species that can coexist at a single point was examined by point-quadrat sampling of a lawn. Three treatments were examined: Control, Herbicide-treated to remove grasses, and Mechanically perturbed to remove all plants, with 10 replicates of each. The Control plots showed an almost constant degree of niche limitation, variance in richness between points being half that expected under the null model. The herbicided plots showed a significantly lesser degree of niche limitation for the first three months after herbiciding, even though the degree of plant overlap had already recovered by the first sampling time. Six weeks after mechanical perturbation, there was no evidence of niche limitation, but the extent of, and statistical evidence for, niche limitation increased until, 10 months after perturbation, community structure was as strong as in the Control.     

Grinnellian and Eltonian niches and geographic distributions of species

In the recent past, availability of large data sets of species presences has increased by orders of magnitude. This, together with developments in geographical information systems and statistical methods, has enabled scientists to calculate, for thousands of species, the environmental conditions of their distributional areas. The profiles thus obtained are obviously related to niche concepts in the Grinnell tradition, and separated from those in Elton's tradition. I argue that it is useful to define Grinnellian and Eltonian niches on the basis of the types of variables used to calculate them, the natural spatial scale at which they can be measured, and the dispersal of the individuals over the environment. I use set theory notation and analogies derived from population ecology theory to obtain formal definitions of areas of distribution and several types of niches. This brings clarity to several practical and fundamental questions in macroecology and biogeography.     

Food resource and temporal partitioning amongst a guild of predatory agroecosystem-inhabiting ant species

Prey diversity and temporal foraging patterns of six abundant,predatory ant species were investigated seasonally in an agroecosystem with two main vegetable crops.Pheidole sp.demonstrated the highest predation success and therefore appears to be the dominant species while Tapinoma melanocephalum showed the lowest success under the natural field conditions.Investigation of prey diversity and temporal activity patterns with the null model tests of niche overlap revealed a significant overlap indicating that t...     

Nest-niche differentiation in two sympatric columbid species from a Mediterranean Tetraclinis woodland: Considerations for forest management

Studies of niche partitioning among Columbid species have mainly addressed food habits and foraging activities, while partitioning in relation to nest-niche differentiation has been little studied. Here we investigate whether two sympatric columbid species—Woodpigeon (Columba palumbus) and Turtle dove (Streptopelia turtur)—occupy similar niches. A total of 74 nests were monitored: 37 nests for each species. The study, conducted in June 2016, attempted to determine the factors that may play a role in nest-niche differentiation among the two sympatric columbid species in a Moroccan Thuya (Tetraclinis articulata) forest. We used Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) to test the relevance of nest placement, proximity of food resources, forest edge and human presence variables in the nest distribution of the two species. The results show substantial niche segregation in the T. articulata nest-trees selected by Woodpigeons and Turtle doves, with selection depending primarily on the tree size and nest height. Observed nest-niche partitioning may diminish the potential for competition between these species and enhance opportunities for their coexistence. Management policies and practices aimed at ensuring the presence of mixed-sized class of Thuya trees must be prioritized. We recommend additional studies designed to: (1) reproduce the same experimental approach on other Mediterranean Thuya forests to improve our understanding of the effects of different levels of anthropogenic disturbance on the breeding behaviour of these two game species; (2) better understand the spatio-temporal dynamics of Woodpigeon and Turtle dove coexistence in the region; and (3) better identify the spatio-temporal extent of the effect of forest management on Woodpigeon and Turtle dove site occupancy.     

九龙山濒危植物南方铁杉的生态位研究

采用生态位理论研究了南方铁杉在九龙山群落中的地位。结果表明：乔木层中,南方铁杉（Tsuga tchekiangensis）、猴头杜鹃（Rhododendron simiarum）、木荷（Schima superba）生态位宽度较大,它们之间的生态位相似性比例值较高,生态位重叠值较大;灌木层中,南方铁杉、猴头杜鹃、朱砂根（Ardisia crenata）、木荷、三角枫（Acer buergerignum）的生态位宽度较大,南方铁杉与这几个树种之间的生态位相似性比例值较高,生态位重叠值较大;这些分析结果为珍稀濒危植物南方铁杉种群数量的扩增具有一定的理论价值。