Niche Overlap Index Research Articles

Antifungal modes of action of Saccharomyces and other biocontrol yeasts against fungi isolated from sour and grey rots

The aim of this study was to determine the putative modes of action of 59 viticultural yeasts (31 Saccharomyces and 28 non-Saccharomyces) that inhibited fungi isolated from sour and grey rot in grapes. Inhibition of fungal mycelial growth by metabolites, enzyme activities (laminarinases, chitinases), antifungal volatiles, competition for nutrients (siderophores, Niche Overlap Index (NOI)), inhibition of fungal spore germination and decreased germinal tube length and induction of resistance were assayed. Biofungicide yeasts were classified into “antifungal patterns”, according to their mechanisms of action. Thirty isolates presented at least two of the mechanisms assayed. We propose that inhibition of fungal mycelial growth by metabolites, laminarinases, competition for nutrients, inhibition of fungal spore germination and decreased germinal tube length, and antifungal volatiles by Saccharomyces and non-Saccharomyces viticultural yeasts is used as putative biocontrol mechanisms against phytopathogenic fungi. Twenty-four different antifungal patterns were identified. Siderophore production (N)and a combination of siderophore production and NOI>0.92 (M)were the most frequent antifungal patterns observed in the biofungicide yeasts assayed. Elucidation of these mechanisms could be useful for optimization of an inoculum formulation, resulting in a more consistent control of grey and sour rot with Saccharomyces and non-Saccharomyces biocontrol yeasts.

Food sources and trophic relationships of three decapod crustaceans: insights from gut contents and stable isotope analyses

Chinese mitten crab (Eriocheir sinensis), freshwater shrimp (Macrobrachium nipponensis) and red swamp crayfish (Procambarus clarkii) are important culture species in China and have world-wide introduced distributions. The trophic role of these three decapods has not been compared within a system although they consume plants, animals, and detritus and often co-occur in freshwater ponds. A combination of stable isotope measurements and gut content analysis was used to determine the main food sources and trophic niche of three benthic decapods, in commercial crab ponds around Lake Gucheng, China. Observation of the gut contents reflected a variety of prey items ingested by three decapods. Macrophytes made up the highest contribution to the volume of their gut contents, followed by forage fish, corn and mollusks. Stable isotope analysis supported a stronger relationship between crayfish and vegetable matter than with animal matter, while both crab and shrimp were the opposite. An isotopic mixing model indicated that about 60% of crab and shrimp production originated from animal matter, while only 40% of crayfish production was ascribed to consumption of animal matter. Although results from the mixing model corroborate the gut content findings in most cases, stable isotope results showed that three decapods obtained more energy for growth from animal matter than what would be estimated if gut analysis was used alone. Estimates of niche overlap indices indicated a high degree of dietary overlap among the three decapods examined, suggesting that shrimp and crayfish density should be controlled if considering economic benefits of pond aquaculture.

Implications of low food availability on resource partitioning among three species of Cichlidae (Pisces: Perciformes) in a Brazilian semi-arid reservoir

AimResource partitioning has been recognized as a major driver affecting fish communities, with the potential to reduce interespecific competition. This is the result of differences in feeding apparatuses and feeding mode, location of the fish species in the water column and swimming ability, as well as type and size of prey and its availability. The present study surveys a highly limited aquatic system in semi-arid Brazil with regard to habitat and food availability, with very low diversity of fish, and poor in underwater habitat structures and prey, with the objective of understanding resource partitioning among fish species under such conditions.MethodsThree species of Cichlidae (Pisces: Perciformes) were sampled during the dry and wet seasons and had their stomach contents analyzed to evaluate food consumption. The resource partition among fish species was evaluated based on Pianka’s niche overlap index and tested for significance against null models.ResultsIt was observed a low overlap among the study species in food resource use, with individuals tending to specialize to select some food items. This is likely the result of low natural variation in abundance of specific food items associated with fish preferences (both morphological and behavioral).ConclusionsThese results support evidence that, in Brazilian semi-arid aquatic systems, coexistence of fish species seems to be enhanced by the partition of food items at specific trophic levels. Within this context, flow variability would have a key hole in fish coexistence by promoting a high diversity of aquatic habitat elements available for colonization of fish and their prey. Furthermore, food resources available to fish play an important role in this dynamics since prey foods are expected to vary in abundance as the habitat changes.

Climate niche differentiation between two passerines despite ongoing gene flow.

Niche evolution underpins the generation and maintenance of biological diversity, but niche conservatism, in which niches remain little changed over time in closely related taxa, and the role of ecology in niche evolution are continually debated. To test whether climate niches are conserved in two closely related passerines in East Asia - the vinous-throated (Paradoxornis webbianus) and ashy-throated (P. alphonsianus) parrotbills - we established their potential allopatric and sympatric regions using ecological niche models and compared differences in their climate niches using niche overlap indices in background tests and multivariate statistical analyses. We also used polymorphism data on 44 nuclear genes to infer their divergence demography. We found that these two parrotbills occupy different climate niches, in both their allopatric and potential sympatric regions. Because the potential sympatric region is the area predicted to be suitable for both parrotbills based on the ecological niche models, it can serve as a natural common garden. Therefore, their observed niche differences in this potential sympatry were not simply rendered by phenotypic plasticity and probably had a genetic basis. Our genetic analyses revealed that the two parrotbills are not evolutionarily independent for the most recent part of their divergence history. The two parrotbills diverged c. 856,000 years ago and have had substantial gene flow since a presumed secondary contact c. 290,000 years ago. This study provides an empirical case demonstrating that climate niches may not be homogenized in nascent species in spite of substantial, ongoing gene flow, which in turn suggests a role for ecology in promoting and maintaining diversification among incipient species.

南黄海春季大型底栖动物优势种生态位分析

PDF HTML阅读 XML下载 导出引用 引用提醒 南黄海春季大型底栖动物优势种生态位 DOI: 10.5846/stxb201305311254 作者: 作者单位: 中国科学院海洋研究所,中国科学院海洋研究所,青岛市市市南区南海路7号中国科学院海洋研究所标本馆,青岛市市市南区南海路7号中国科学院海洋研究所标本馆 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点基础研究发展计划项目(973)(2011CB403605);国家自然科学基金面上项目(41176133) Niche analysis of dominant species of macrozoobenthic community in the southern Yellow Sea in spring Author: Affiliation: Institute of Oceanology,Chinese Academy of Sciences,Institute of Oceanology,Chinese Academy of Sciences,Institute of Oceanology,Chinese Academy of Sciences,Institute of Oceanology,Chinese Academy of Sciences 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:2011年4月对南黄海大型底栖动物进行定量采样调查,获得大型底栖动物105种,筛选获得优势种20种,隶属3门3纲17科。南黄海大型底栖动物优势种以运动、有颌、表层沉积物取食者相对丰度较高,占27.6%。对选取的20个优势种以Shannon-Wiener指数为基础进行了生态位宽度测定,以Pianka 重叠指数为基础进行了生态位重叠值分析,以平均边缘指数(OMI)和耐受指数(TOI)为基础分析了物种生态位与环境之间的相互关系。结果表明:南黄海大型底栖动物群落优势种生态位宽度变化范围为1.24-2.15,生态位宽度值较高的有薄索足蛤、蜈蚣欧努菲虫、掌鳃索沙蚕、浅水萨氏真蛇尾、黄海刺梳鳞虫和寡节甘吻沙蚕;优势种OMI指数变化范围为0.23-4.95,OMI指数值较高的有拟特须虫和细弱吻沙蚕;优势种耐受指数值变化范围为0.13-3.85,值较高的有深钩毛虫、寡鳃齿吻沙蚕和黄海刺梳鳞虫;优势种生态位之间的重叠值不均一,在0-0.95之间,长叶尖索沙蚕和掌鳃索沙蚕生态位重叠值较高,为0.95;平均边缘指数分析随机置换显著性检验表明:水深、水温、盐度、沉积物粒径、沉积物总有机碳和总氮与长吻沙蚕、细弱吻沙蚕、背蚓虫、角海蛹和浅水萨氏真蛇尾生态位之间的相互关系较显著(P < 0.05)。对群落优势种进行聚类和多维度排序分析,结果表明20个物种可分为广布种、典型生境种和特化种,主坐标分析反映了优势种在不同资源位点的分布状况,支持聚类和排序的结果。研究表明,优势种生态位的宽度、优势种之间的重叠值与物种摄食功能类群、生活型、资源位上的分布、物种数量及生境状况密切相关,反映了大型底栖动物群落中各物种对生境资源的不同利用能力。 Abstract:A quantitative survey to determine the composition of the macrobenthic communities in the southern Yellow Sea was conducted in April 2011. Over 100 species of macrobenthos were identified. Twenty dominant species, belonging to 17 families, 3 classes and 3 phyla, were determined via rank abundance curve analysis. Surface deposit feeding, motile, jawed feeders (27.6%) were the feeding group with the highest relative abundance values, while surface deposit feeding, sessile, tentaculate feeders were the least abundant (1%). The Yellow Sea Cold Water Mass benthic community was dominated by both carnivorous, motile, non-jawed species and carnivorous, motile, jawed feeders, making up 32.3% and 29.7% of the community composition. In the Mixed community the trophic groups were dominated by both surface deposit feeding, motile, jawed and burrowing, motile, non-jawed feeders (46% and 30%, respectively). Surface deposit feeding, motile, jawed feeders (32.8%) was the most abundant macrobenthos category in the Eurythermal community, while in the Yangtze River Estuary community burrowing, motile, non-jawed and surface deposit-feeding, motile, non-jawed feeders represented 43.8% and 31.3% of the total abundance, respectively. The Shannon-Wiener Niche Breadth index, the Pianka Niche Overlap index, the outlying mean index (OMI) and the tolerance index (TOL) were used to analyze the relationships of the dominant species and environmental factors. Four indices were significantly different among species. Thyasira tokunagai, Onuphis geophiliformis, Nine palmata, Ophiura sarsii vadicola, Ehlersileanira hwanghaiensis and Glycinde gurjanovae had large niche breadths. The OMI varied from 0.23 to 4.95. Paralacydonia paradoxa and Glycera tenuis had higher values of OMI (4.95 and 4.78) than that of any other species and the most marginal niche positions of all the dominant species examined. N. palmata (0.23) and Kuwaita heteropoda (0.38) had relatively non-marginal niche positions, and occurred in average conditions across the sampled sites. The tolerance index ranged from 0.13 to 3.85. Sigambra bassi (3.85), Nephtys oligobranchia (2.46) and E. hwanghaiensis (2.25) were the main contributors to the tolerance index. OMI analysis indicated that two species with lower tolerances (narrower niche breadths; more specialized species) were G. tenuis and Paramphicteis angustifolia. Niche overlaps varied from 0 to 0.95. Scoletoma longifolia and N. palmata had a niche overlap value close to 0.95. The significance of the OMI analysis random permutation test demonstrates that niche segregation of Glycera chirori, G. tenuis, Notomastus latericeus, Ophelina acuminate and O. sarsii vadicola is effective along a given environmental gradient (e.g., depth, water bottom temperature, salinity, median sediment size, total organic carbon and total nitrogen). Using hierarchical clustering (CLUSTER) with between-group linkage and non-metric multidimensional scaling (NMDS), the 20 dominant species were classified into three groups: generalist species, typical habitat species and specialist species. We also used Principal Coordinates Analysis to visualize the distribution patterns of dominant species in different habitats. Niche breadth and niche overlap of each species were strongly related to functional feeding groups, habit/behaviors of species, spatial distribution, species abundance and habitat conditions. This reveals the differing abilities of species to effectively utilize their environmental resources. 参考文献 相似文献 引证文献

Chironomidae larvae (Diptera) of Neotropical floodplain: overlap niche in different habitats.

The niche overlap between trophic groups of Chironomidae larvae in different habitats was observed between trophic groups and between different environments in Neotropical floodplain. For the evaluation we used the index of niche overlap (CXY) and analysis of trophic networks, both from the types and amount of food items identified in the larval alimentary canal. In all environments, the larvae fed on mainly organic matter such as plants fragments and algae, but there were many omnivore larvae. Species that have high values of food items occurred in diverse environments as generalists with great overlap niche and those with a low amount of food items with less overlap niche were classified as specialists. The largest number of trophic niche overlap was observed among collector-gatherers in connected floodplain lakes. The lower values of index niche overlap were predators. The similarity in the diet of different taxa in the same niche does not necessarily imply competition between them, but coexistence when the food resource is not scarce in the environment even in partially overlapping niches.

Does hatchery-reared Siniperca chuatsi (Actinopterygii, Perciformes) compete significantly with two wild Siniperca populations for diets in a shallow lake?

This study aimed to evaluate whether hatchery-reared Siniperca chuatsi (HSC) competes significantly with wild Siniperca populations in a shallow lake. Two wild Siniperca fishes, S. chuatsi and Siniperca kneri, along with HSC, were collected in the shallow Biandantang Lake, and their diets were determined using both stomach contents and stable isotope analyses. The stomach contents showed that shrimps and fish were the major food items of HSC and wild Siniperca fishes, but their dietary composition and percentage contribution revealed significant differences. Isotopic mixing model analysis suggested similar conclusions that contribution proportions of end members were significantly different. The niche overlap index on the basis of prey importance from stomach content analysis indicated that there was not significant diet overlap between hatchery-reared and wild Siniperca populations in winter and summer. Similar results were found in winter based on the prey contributions from isotopic mixing model outputs, but meaningful diet overlap was observed in summer. Our findings demonstrated that HSC did not have apparent feeding competition with wild Siniperca fishes during the critical periods of the early stocking stages, suggesting that moderate stocking of HSC may not have a negative effect on the variability of wild Siniperca populations.

北部湾北部生态系统结构与功能研究VI：浮游动物空间生态位及其分化

根据2006-2007年北部湾北部海域4个航次调查资料，采用<em>K</em>-优势度曲线法对浮游动物种（类）群进行排序分析，运用Levins公式和Pianka指数分析了主要优势种（类）群的生态位宽度值和生态位重叠程度，并通过除趋势典范对应分析（DCCA）研究生态位分化状况。结果表明，该海区浮游动物优势种（类）群按生态位宽度值可划分为广生态位、中生态位和窄生态位三大类型。其中，广生态位的种（类）群如肥胖软箭虫、亚强次真哲水蚤、长尾类幼体等具有较强的生态适应性，生活范围较广；窄生态位的种（类）群，对环境的适应性较差，对海流和水团等环境因素的变化具有指示意义。生态位宽度能够反映种（类）群丰度季节变化，但不能反映具体丰度大小。北部湾北部全年主要优势种（类）群的生态位宽度值介于0.08-0.77之间，并且各优势种（类）群的生态位宽度差异较大，种对间生态位重叠值介于0.02-0.89之间，平均生态位重叠指数为0.45，种（类）群之间利用资源环境的互补性较强，这与海域内生境多样化并且各优势种对环境适应能力的差异存在一定联系。DCCA分析表明，影响浮游动物分布的主要因子是水深、温度和盐度，其次是叶绿素a和溶解氧。;The concept of ecological niche had remained as one of the core ideas in ecological research for almost a century, which was closely linked with interspecific competition, resource utilization had played an important role in the study of community composition and function,of the relationships among species,biodiversity,community succession and population evolution. Based on four seasonal investigations (Spring 2007, Summer 2006, Autumn 2007 and Winter 2006) in northern Beibu Gulf from 2006 to 2007, the niche breadth, niche overlap, spatial differentiation and environment effects on the abundance and spatial distribution of zooplankton were studied with qualitative and quantitative methods. The cumulative top 80% of zooplankton dominant populations were selected by the K-dominant curve method, then the niche breadths and their overlaps of zooplankton were measured using the formulas proposed by Levins Niche Breadth index and the Pianka Niche Overlap index, and the spatial niche differentiation was studied by using Detrended Canonical Correspondence Analysis (DCCA) method. The results showed that the zooplankton dominant species in northern Beibu Gulf were classified in to three groups, <em>i e.,</em> wide niche breadth groups (<em>B</em>_i=0.60-0.77), middle niche breadth groups (<em>B</em>_i=0.30-0.60), narrow niche breadth groups (<em>B</em>_i=0.08-0.30) based on the niche breadth value. The niche breadths of zooplankton such as <em>Sagitta enflata</em>, <em>Subeucalanus subcrassus</em> and Macrura larvae were wider, which was related with their own characteristics and the capability of adapting environment, while the species whose niche breadths were narrower such as <em>Doliolum denticulatum</em> and <em>Dolioletta gegenbauri</em> will be considered as an indicative significance for ocean currents and water masses. Niche breadth could reflect the zooplankton abundance with the seasonal dynamic changes,and also could objectively reflect the species in the habitat in which the distributions of degree but it could not reflect the Accurate zooplankton abundance. The niche breadth values of dominance zooplankton species ranged between 0.08 and 0.77 in the whole year and The niche breadth difference among the dominant populations was great; The niche overlap values of dominance zooplankton species ranged between 0.02 and 0.89 in the whole year and the average niche overlap index was 0.45, there was strong complementarity in terms of the utility of resource among zooplankton populations, which had certain relationship with northern Beibu Gulf habitat diversification and the strong complementarity in terms of the utility of resource among zooplankton populations. The Detrended Canonical Correspondence Analysis result showed that depth, temperature and salinity had more important influence on the species spatial distribution than Chlorophyll a and dissolved oxygen.

Melittopalynology and Trophic niche analysis of Apis cerana and Apis mellifera in Yunnan Province of Southwest China

The present study reports results of qualitative melittopalynological analyses of 34 honey samples of Apis cerana and Apis mellifera between 2011 and 2012 in Mengzi (China Yunnan) and the trophic niche analysis of two bee species on pollen food resources. A diverse spectrum of 17 pollen types from 14 families was identified with the Asteraceae and Myrtaceae being most frequent at non-nectar flow and the Lythraceae being most frequent at main nectar flow of pomegranate. The results of trophic niche analysis to Apis cerana and Apis mellifera are these, at non-nectar flow, the Niche breadth are 0.65 and 0.57, respectively; at nectar flow, the values are 0.41 and 0.24, respectively. Trophic niche overlap index, the value of nectar flow(0.68) is greater than non-nectar flow(0.61). Interspecific competition index, the value of nectar flow(0.92) is also greater than non-nectar flow(0.77). These results may promote the development of local beekeeping and help scholars assessing the impact of introduced bees on native bees in China.

Foraging ecology and niche overlap in pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales from waters of the U.S. mid‐Atlantic coast

AbstractA complementary approach of stomach content and stable isotope analyses was used to characterize the foraging ecology and evaluate niche overlap between pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales stranded on the U.S. mid‐Atlantic coast between 1998 and 2011. Food habits analysis demonstrated both species were primarily teuthophagous, with 35 species of cephalopods, and 2 species of mesopelagic fishes represented in their overall diets. Pianka's Index of niche overlap suggested high overlap between whale diets (On= 0.92), with squids from the families Histioteuthidae, Cranchidae, and Ommastrephidae serving as primary prey. Pygmy sperm whales consumed slightly larger prey sizes (mean mantle length [ML] = 10.8 cm) than dwarf sperm whales (meanML= 7.8 cm). Mean prey sizes consumed by pygmy sperm whales increased with growth, but showed no trend in dwarf sperm whales. Significant differences were not detected inδ15N andδ13C values of muscle tissues from pygmy (10.8‰ ± 0.5‰, −17.1‰ ± 0.6‰), and dwarf sperm whales (10.7‰ ± 0.5‰, −17.0‰ ± 0.4‰), respectively. Isotopic niche widths also did not differ significantly and dietary overlap was high between the two species. Results suggest the feeding ecologies of the pygmy and dwarf sperm whales are similar and both species occupy equivalent trophic niches in the region.

Alimentación de dos especies de anfibios (Anura: Hylidae) en la estación de bajas temperaturas y su relación con la acumulación de energía en Santa Fe, Argentina

Feeding of two amphibian species (Anura: Hylidae) during the low temperatures season and its relationship with energy storage in Santa Fe, Argentina. In environments with thermal and pluvial seasonality such as those of the Middle Paraná River floodplain (Province of Santa Fe, Argentina), most amphibian species reproduce during the warm season and drastically diminish their activity during winter. Even though, a few species remain active during the cold season, such as Hypsiboas pulchellus that has its reproductive peak during the autumn-winter period (and the consequent energy demand). The objective of this study was to analyze and compare the feeding and development of fat bodies during the low temperature season for H. pulchellus and Dendropsophus nanus. We analyzed entire gastrointestinal tract contents of both species (H. pulchellus = 110 specimens; D. nanus = 114 specimens) and applied an index (IRI%) that combines prey abundance, volume and frequency to describe frogs diets; we used fat bodies weights as indicators of stored energy reserves. We compared diet between species with a niche overlap index (Ojk: 0-1) and used null models to ascribe statistical significance to evaluate overlap; and we analyzed variation in empty guts proportions through months and between species. Also, using ANCOVAs we explored differences in fat bodies, number and volume of prey consumed along months, between species and sexes. The most important preys in H. pulchellus diet during the cold season were Araneae (IRI% = 34.96), Chironomidae (IRI% = 33.08), Tipulidae (IRI% = 11.44) and Gryllidae (IR1% = 7.31); while for D. nanus, Chironomidae (IR1% = 48.14), Tipulidae (IRI% = 18.41), Psychodidae (IRI% = 7.44) and Araneae (IRI% = 7.34). Diet overlap between species was elevated (Ojk=0.78) and higher than expected by chance (mean simulated indices: Ojk = 0.04; p[observed > or = expected]<0.01; p[observed < or = expected] = 1). In H. pulchellus there was a monthly variation in number of prey per gut, while in D. nanus there was a difference in fat bodies development between sexes. Fat bodies development, number of prey per gut and preys volume also varied between species. Despite diet similarity between H. pulchellus and D. nanus, each species showed a different strategy to accumulate energy and support their activity during the cold season. The low rate of gastrointestinal emptiness in H. pulchellus (< 10% in any analyzed month) together with the poor development of their fat bodies, allows us to point out that, to sustain the breeding elevated energy demands, this species continues with a high feeding rate even at the low temperatures of cold season. On the other hand, the rate of gastrointestinal emptiness of D. nanus was higher than that of H. pulchellus (May = 17.24%, July = 22.22% and August = 35.71%), while their fat bodies were well developed. Thus, D. nanus would depend more on their stored reserves to sustain the energy demands of being active during the low temperatures season and hence would reach the reproductive season in spring-summer in good body condition.

Comparison of growth, nutritional utilisation patterns, and niche overlap indices of toxigenic and atoxigenic Aspergillus flavus strains

The effects of temperatures (20–30 °C) and water activity (0.90–0.99 aw) on the lag phase duration, mycelial growth, and nutritional utilisation patterns of two toxigenic (AFL1+ & AFL2+) and three atoxigenic (AFL1−, AFL2−, & AFL3−) Aspergillus flavus strains were evaluated in vitro. Both temperature and aw and their interactions had a significant influence on the growth and nutritional utilisation patterns (p < 0.05). There were no significant differences between toxigenic and atoxigenic strains in terms of lag phase prior to growth and mycelial growth rates. Based on carbon source (CS) utilisation patterns, toxigenic and atoxigenic strains' niche size was greater at higher temperatures and in wetter conditions. Additionally, based on niche overlap indices (NOIs), regardless of temperature, when water was freely available, atoxigenic and toxigenic strains co-existed. However, under moisture stress, the nutritional competitiveness was variable. Temporal carbon utilisation sequences (TCUS) of toxigenic and atoxigenic strains were compared. At 0.99 aw most CS sources were utilised by the strains and the time to detection (TTD) of each strain was shortest on monosaccharides at the same level of aw. Conversely, under moisture stress the least number of CS was utilised. The current study has demonstrated that carbon utilisation patterns are equally important as are other determinants of competitiveness and that growth rate alone is not a key attribute which determines competitiveness.

Dietary overlap and niche partitioning of sympatric harbour porpoises and Dall’s porpoises in the Salish Sea

Ecological theory regarding the coexistence of similar species predicts resource partitioning will arise through competition and lead to different ecological niches. The diets of harbour porpoises (Phocoena phocoena) and Dall’s porpoises (Phocoenoides dalli) in the Salish Sea were investigated for evidence of resource partitioning between these ecologically similar species. Stomach contents of 36 harbour porpoises and 11 Dall’s porpoises were analysed and ten and six fish taxa were identified in each, respectively. Pacific herring (Clupea pallasi) was important in the diet of both porpoise species and walleye pollock (Theragra chalcogramma) was second in importance in the Dall’s porpoises. Pacific herring was estimated to contribute 60% to the total caloric intake of harbour porpoises. In addition to herring, Pacific hake (Merluccius productus), walleye pollock and a species of Pyschrolutidae were present in the diet of both porpoise species. Pianka’s Index of niche overlap indicated substantial dietary overlap between the porpoise species based on measures of prey frequency of occurrence and prey percent numerical abundance. These results seem contrary to predictions from ecological theory. However, habitat and activity pattern differences between the two porpoise species exist and represent other dimensions of niche that likely contribute to resource partitioning in ways that were not strongly evident in stomach contents. Dall’s porpoises, which prefer deeper water habitat in the Salish Sea than harbour porpoises, may feed more on walleye pollock which spawn in deep water. Dall’s porpoises are also known to feed at night when lipid-rich mesopelagic prey such as Myctophidae and Bathylagidae, both present in the Dall’s porpoise samples, migrate upwards from depths in excess of 200m. In contrast shiner perch, present only in harbour porpoise samples, is a species associated with shallow nearshore habitats. Resource partitioning is also likely to occur in accordance with seasonal prey availability.

Seedling recruitment factors in low‐diversity Hawaiian wet forest: towards global comparisons among tropical forests

Recruitment limitations determine forest community regeneration patterns. Source limitation and dispersal limitation contribute to overall seed limitation, while environmental conditions and habitat associations influence establishment limitation. Several hypotheses have made contradictory predictions for how the relative importance of these limitations should vary with diversity. However, comparative data have not been available for low‐diversity tropical forests. We quantified recruitment limitations using 2.5 yrs of seed rain and seedling distribution data collected within a 4 ha forest dynamics plot in low‐diversity native‐dominated Hawaiian wet forest. We further quantified seedling irradiance and substrate habitat associations and niche overlap (using Pianka's niche overlap index). Additionally, we compared recruitment limitations and the frequency of seedling habitat associations across forests using the few available published data from sites employing similar field and analytical methods. In Hawaiian wet forest, seed dispersal more strongly limited recruitment than did establishment limitation across species, with 11 of 18 species completely seed limited (i.e., no seeds found). However, the relative importance of limitations varied greatly among species. For the three most abundant species, habitat conditions more strongly limited regeneration than did seed arrival, especially for the dominant canopy species, Metrosideros polymorpha, which was not seed limited. Most species were significantly associated with specific ranges of irradiance and/or substrates. Although habitat associations may indicate niche differentiation, Hawaiian species also showed significant niche overlap. Across the three forests compared, community‐wide mean seed and establishment limitation values were similar, despite wide variation in diversity. However, recruitment limitations differed strongly among species within forests due to species' life‐history differences. While seed limitation in Hawaiian forest was as high as in high‐diversity forests, mechanisms may differ; seed limitation in Hawaii may arise from loss of pollinators and dispersers rather than from a high proportion of rare species as occurs in high‐diversity forests. The strong habitat associations in Hawaiian forest relative to high‐diversity forests supported theoretical expectations that lower species diversity should increase the importance of habitat associations. However, these habitat associations were not linked to niche differentiation in Hawaii. Our findings suggest that high recruitment limitation may facilitate coexistence despite niche overlap in low‐diversity Hawaiian forest.

Resource partitioning in three syntopic forest-dwelling European bat species (Chiroptera: Vespertilionidae)

Resource partitioning in syntopic bats is mainly studied through comparative ecomorphology and behavioural ecology. We used simultaneous radio-tracking of syntopic forest-dwelling bats, the western barbastelle (Barbastella barbastellus), Bechstein’s bat (Myotis bechsteinii) and the brown long-eared bat (Plecotus auritus) to analyse individual and species-specific foraging habitat and roost site selection. We estimated niche partitioning through Euclidean distance analyses to landscape elements and through Pianka’s niche overlap index for roost types. We analysed a total of 2278 fixes and 54 roosts of 15 bats. Western barbastelles and Bechstein’s bats foraged significantly closer to the forest than brown long-eared bats. Female barbastelles also foraged significantly closer to forest tracks, which were avoided by female brown long-eared and Bechstein’s bats. Female and male brown long-eared bats were found close to open habitats, which were avoided by the other two species. We found a high niche overlap in terms of roost height, but low overlap in terms of roost type and roost tree species among the three bat species. Individual niche variation may allow these specialised forest-dwelling bat species to minimise competition when foraging and roosting in syntopy.

鄂西南木林子常绿落叶阔叶混交林恢复过程中优势树种生态位动态

PDF HTML阅读 XML下载 导出引用 引用提醒 鄂西南木林子常绿落叶阔叶混交林恢复过程中优势树种生态位动态 DOI: 10.5846/stxb201202260255 作者: 作者单位: 湖北省林业科学研究院,湖北民族学院,湖北民族学院,湖北省林业科学研究院,湖北省林业科学研究院,湖北省林业科学研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 湖北省林业重点科研项目(2004KJ03,2006KJ08) Niche dynamics during restoration process for the dominant tree species in montane mixed evergreen and deciduous broadleaved forests at Mulinzi of southwest Hubei Author: Affiliation: Hubei Academy of Forestry,Hubei University for Nationalities,Hubei University for Nationalities, Enshi,Hubei Academy of Forestry,Hubei Academy of Forestry,Hubei Academy of Forestry 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:运用Shannow-wiener生态位宽度指数和Pianka生态位重叠指数,分析了鄂西南木林子常绿落叶阔叶混交林恢复过程中优势树种生态位动态。结果表明:大穗鹅耳枥(Carpinus fargesii)、四照花(Cornus kousa var. Chinensis)、青冈(Cycloblanopsis glauca)生态位总宽度较大,且在5个不同恢复时期均有分布。恢复期14a、35a、60a、85a和110a生态位宽度最大的树种分别为白马桑(Weigela japonica var. sinica)、大穗鹅耳枥、四照花、光皮桦(Betula luminifera)和尾叶冬青(Ilex wilsonii)。随着群落的恢复,优势落叶树种生态位宽度表现出下降趋势,优势常绿树种则呈上升趋势。当恢复到顶极群落阶段,乔木层常绿和落叶树种生态位接近,灌木层常绿灌木占据较大生态位。随着群落的恢复,优势落叶树种与其它树种的生态位重叠值呈波动性下降趋势,优势常绿树种表现为波动性上升趋势,群落全部树种间生态位重叠程度呈小幅度波动性下降趋势。相同或相似生活型的演替早期种间的高生态位重叠,意味着种间对资源利用的相似性和竞争关系,演替后期种与其它树种间的生态位重叠的增加,意味着不同生活型树种在水平空间重叠而在垂直空间分化,这是不同树种对有限环境资源充分利用的一种机制。 Abstract:The niche dynamics during natural restoration process of dominant tree species in montane mixed evergreen and deciduous broadleaved forests at Mulinzi of Southwest Hubei were analyzed by means of Shannow-wiener niche breadth index and Pianka niche overlap index. The results showed that the total breadth of niche of Carpinus fargesii, Cornus kousa var. Chinensis and Cycloblanopsis glauca were higher and theses tree species were found in all five restoration stages. Weigela japonica var. sinica, Carpinus fargesii, Cornus kousa var. Chinensis, Betula luminifera and Ilex wilsonii were the species with the largest niche breadth for the restoration stage of 14, 35, 60, 85 and 110 years respectively. There was a general trend that the niche breadth of dominant deciduous tree species decreased with increasing degree of community restoration, while that of dominant evergreen tree species was on the contrary. When the community restored to its climax stage, the niche of evergreen species in tree layer was close to that of deciduous trees, and that of evergreen species in shrub layer occupied a larger niche; this was a spatial pattern for better sharing of natural resources. With increasing restoration degree of community, the niche overlap between dominant deciduous tree species and other tree species had a trend of fluctuant decrease; while that of dominant evergreen tree species had a trend of fluctuant increase; and the niche overlap among all tree species in communities had a tendency of slightly waved decrease. The results showed that higher niche overlap among the early-succession species with same or similar life form meant a similar or competing requirement on resources. The increase of niche overlap among the late-succession species and other tree species represented a horizontally spatial overlap but vertically spatial differentiation; this is a full use mechanism of different tree species regarding limited resources in their environment. 参考文献 相似文献 引证文献

Temporal niche overlap among insectivorous small mammals

Being active in the same environment at different times exposes animals to the effects of very different environmental factors, both biotic and abiotic. In the present study, we used live traps equipped with timing devices to evaluate the potential role of biotic factors (competition and food abundance) on overall overlap in the temporal niche axis of 4 insectivorous small mammals in high-elevation grassland fields ('campos de altitude') of southern Brazil. Based on resources availability (invertebrates), data on animal captures were pooled in 2 seasons: 'scarcity' (June 2001-September 2001) and 'abundance' (November 2001-May 2002) seasons. We tested for non-random structure in temporal niche overlap among the species in each season. These species were the rodents Oxymycterus nasutus (Waterhouse, 1837), Deltamys sp., Akodon azarae (Fischer, 1829), and the marsupial Monodelphis brevicaudis Olfers, 1818. The studied community was mainly diurnal with crepuscular peaks. Simulations using the Pianka index of niche overlap indicated that the empirical assemblage-wide overlap was not significantly different from randomly generated patterns in the abundance season but significantly greater than expected by chance alone in the scarcity season. All the species showed an increase in temporal niche breadth during the abundance season, which appears to be related to longer daylength and high nocturnal temperatures. Patterns on both temporal niche overlap and temporal niche breadth were the opposite to those that we were expecting in the case of diel activity patterns determined by competition for dietary resources. Therefore, we conclude that competition did not seem to be preponderant for determining patterns of temporal niche overlap by the studied community.

Ecological distribution and spatial niche of pheasants in the Karst mountains of southwest Guangxi Province, China

The Karst mountain area along the Sino-Vietnam border of southwest Guangxi has been designated a "Global Biodiversity Hotspot" since 2003. We conducted a survey of pheasant species in this area, with seven species recorded, namely Chinese Francolin (Francolinus pintadeanus), Bar-backed Partridge (Arborophila brunneopectus), Mountain Bamboo Partridge (Bambusicola fytchii), Chinese Bamboo Partridge (Bambusicola thoracica), Red Junglefowl (Gallus gallus), Silver Pheasant (Lophura nycthemera) and Common Pheasant (Phasianus colchicus). Analysis and comparison of the distribution and spatial niche of these seven pheasant species revealed that Red Junglefowl had the widest spatial niche, while Chinese Francolin had the narrowest. The spatial niche overlap index was high between Chinese Francolin and the Common Pheasant, Chinese Bamboo Partridge, and Red Junglefowl. With narrow distribution range, small population, and lower ecological adaptability, it is likely that the Bar-backed Partridge is the most vulnerable pheasant species in this area. The results suggest more research and conservation measures are required for pheasant habitat protection in the Karst areas of southwest Guangxi.

Climate niche shift in invasive species: the case of the brown anole

Anolis sagrei, a Cuba and Bahama native lizard, is a successful invader in Florida and adjacent areas. Herein, we focus on conservatism in its climate niche axes and possible congruencies with its natural history properties. The not mutually exclusive hypotheses of the present study explaining its northern range limit are: (1) climatic conditions within species' native and invasive ranges are identical; (2) the species is pre-adapted to novel conditions as a result of historical climate variations; and (3) only some niche axes limit the species' invasive distribution and the observed pattern is explained by an interplay between the potential niche within its native range and life-history. Species distribution models for native and invasive distributions were built on ten bioclimatic variables. Using Schoener's niche overlap index, the degree of niche conservatism among variables was identified. Significances of hypothesis (1) were tested using null-model approaches. Possible climatic pre-adaptations were evaluated by comparing its actual tolerance within its invasive range with that of the Last Glacial Maximum (LGM) within its native range (hypothesis 2). Results of (1) and (2) are discussed in relation to natural history, approaching hypothesis 3. We detect varying overlaps in niche axes, indicating that natural history properties are associated with conservative niche axes. Climatic comparisons with LGM of native and current conditions of invasive range suggest that pre-adaptations are unlikely. Possible shifts in the fundamental niche of the species may have been facilitated by enhanced genetic diversity in northern invasive populations. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 943–954.

Isolates of Thermoanaerobacter thermohydrosulfuricus from decaying wood compost display genetic and phenotypic microdiversity

In this study, 12 strains of Thermoanaerobacter were isolated from a single decaying wood compost sample and subjected to genetic and phenotypic profiling. The 16S rRNA encoding gene sequences suggested that the isolates were most similar to strains of either Thermoanaerobacter pseudethanolicus or Thermoanaerobacter thermohydrosulfuricus. Examination of the lesser conserved chaperonin-60 (cpn60) universal target showed that some isolates shared the highest sequence identity with T.thermohydrosulfuricus; however, others to Thermoanaerobacter wiegelii and Thermoanaerobacter sp. Rt8.G4 (formerly Thermoanaerobacter brockii Rt8.G4). BOX-PCR fingerprinting profiles identified differences in the banding patterns not only between the isolates and the reference strains, but also among the isolates themselves. To evaluate the extent these genetic differences were manifested phenotypically, the utilization patterns of 30 carbon substrates were examined and the niche overlap indices (NOI) calculated. Despite showing a high NOI (>0.9), significant differences existed in the substrate utilization capabilities of the isolates suggesting that either a high degree of niche specialization or mechanisms allowing for non-competitive co-existence, were present within this ecological context. Growth studies showed that the isolates were physiologically distinct in both growth rate and the fermentation product ratios. Our data indicate that phenotypic diversity exists within genetically microdiverse Thermoanaerobacter isolates from a common environment.