Evolutionary history and precipitation seasonality shape niche overlap in Neotropical bat–plant pollination networks

Species interactions are one dimension of a niche. Niche overlap arises when two species share an interaction partner. In pollination systems, environmental and biotic factors affect niche overlap. Here, we explored the effects of climate seasonality, plant and bat richness, morphological traits, and phylogenetic distance in shaping the niche overlap of Neotropical bat–plant pollination networks. We examined a dataset of 22 bat–plant pollination networks in the Neotropical region. We measured niche overlap in bats and plants with the Morisita-Horn index (Ĉ_H) and used a SAR model to test the relationships between niche overlap and both abiotic and biotic factors. We found a lower niche overlap among bats in communities composed of phylogenetically distant bat species. Moreover, plant and bat overlap was lower in regions with higher precipitation seasonality. Our results indicate that climate seasonality and bat evolutionary history drive niche overlap in Neotropical bat–plant pollination interactions. These findings suggest that a higher precipitation seasonality promotes the emergence of temporal modules, which reduces niche overlap, likely due to seasonal species phenologies. Furthermore, the method used to record the interactions affects the degree of niche overlap. Interactions recorded with pollen samples tend to have higher niche overlap than direct observations. The responses of morphological traits and phylogenetic distances in bat niche overlap were uncoupled, suggesting an effect of historical processes independent of morphological traits. Our findings reinforce the importance of evolutionary history and ecological processes in imprinting patterns of interaction niche overlap.     

滇西北高原藏区小型兽类体表寄生蚤的生态位特征

为探讨云南西北高原藏区小型兽类体表寄生蚤的生态位特征,根据海拔和地形等自然环境特点,在德钦县选取42个调查样点,划分为5个垂直带,4种生境,采用铗夜法和笼日法捕获小兽,梳捡其体表寄生蚤,运用生态位宽度指数（B_i）和生态位重叠指数（NO）对其生态位特征进行分析。结果：共梳捡寄生蚤1275头,隶属4科9亚科17属33种,其中迪庆额蚤和云南栉眼蚤为优势种,常见种12种,稀有种19种。在海拔资源轴上,B_i值前三分别是特新蚤德钦亚种0.698、棕形额蚤0.690、斯氏新蚤川滇亚种0.667;生境资源轴上,B_i值前三分别是：无值大锥蚤0.630、特新蚤指名亚种0.57、特新蚤德钦亚种0.537;寄主资源轴上,B_i值前三为绒鼠怪蚤0.584、迪庆额蚤0.567、棕形额蚤0.553;多维生态位宽度来看,特新蚤德钦亚种和迪庆额蚤B_i值较大,分别为1.031、1.019。海拔、生境、寄主生态位重叠指数中,有意义的重叠种对分别占比35.6%、39.39%、9.28%;完全不重叠的种对分别占比26.89%、18.56%、51.14%;完全重叠的种对分别占比2.27%、13.26%和0.19%。三种生态因子中,优势种和常见种的生态位宽度值较大,对资源的利用能力和竞争能力较强。不同生态因子的生态位重叠指数格局不同,与资源轴本身有关。有意义的重叠和完全不重叠的种对占比较多,前者多为优势种、常见种、稀有种两两之间重叠,重叠指数越高,竞争关系越激烈;完全不重叠的种对多为稀有种之间,无资源利用竞争关系。总体来说,德钦县小兽体表寄生蚤种类丰富,生态位分化较为均匀,本研究可为该地蚤传疾病的监测防控提供生态学依据。     

Niche Overlap and Network Specialization of Flower-Visiting Bees in an Agricultural System

Different resource use strategies manifest as differences in the realized niches of species. Niche segregation may involve several dimensions of the niche, such as diet, space, and time. We measured the level of redundancy and complementarity of a bee–plant interaction network in an agricultural system. Because flower resource diversity is high and resource abundance associated with flowering phenology varies throughout the year, we hypothesized that trophic overlap in the community would be low (i.e., high niche complementarity). In contrast, we expected a combination of physiological constraints and exploitation competition to create high temporal overlap, leading to high redundancy in the time of use of floral resources. Dietary overlap was low (NO_ih?=?0.18): niches of 88% of species pairs had less than 30% overlap. In contrast, temporal overlap was intermediate (NO_ih?=?0.49): niches of 65% of species pairs had 30% to 60% overlap. Network analysis showed that bees separated their dietary niches and had intermediate complementary specialization (H₂′?=?0.46). In terms of their temporal niches (H₂′?=?0.12), bees were generalists, with high temporal redundancy. Temperature was not a key factor in the determination of niche overlap, suggesting that environmental factors do not likely have a primary role in determining high redundancy in the temporal use of floral resources. Rather, temporal overlap is likely associated with the timing of nectar production by flowers. Our results suggest that bees partition a wide variety of available floral resources, resulting in low dietary overlap and intermediate temporal overlap.     

若尔盖不同生境植物多样性与植物竞争强度和生态位重叠度的关系

植物多样性与植物竞争强度和生态位重叠度的关系会随环境发生变化。为探究上述关系在若尔盖地区的表现形式,于2021年8月对若尔盖地区典型的水生、湿生、湿生-中生和中生植物群落进行调查,构建了新的植物竞争强度（Competition intensity,CI）公式并进行测算,计算了植物群落的植物多样性指数（包括物种丰富度、Shannon-Weiner指数、Simpson指数和Pielou均匀度指数）和生态位重叠度（Niche overlap of species,NOS）,分析了植物群落物种多样性指数与CI和NOS的关系。结果表明：1）从水生到中生生境,植物多样性指数均呈增加趋势（P<0.05）;2）湿生-中生生境的CI显著高于湿生生境（P<0.05）,湿生生境的NOS高于水生生境（P<0.05）;CI与NOS无显著相关性,但在湿生生境中两者呈倒抛物线关系（P<0.05）。3）整体来看,植物群落的物种丰富度与CI呈抛物线关系（P<0.05）,与NOS无显著关系（P>0.05）;Shannon-Weiner指数、Simpson指数和Pielou均匀度指数均与NOS呈线性正相关（P<0.05）,与CI无显著关系（P>0.05）;从单个生境看,湿生-中生生境的Simpson指数、Shannon-Weiner指数和Pielou均匀度指数与CI呈线性负相关（P<0.05）,其余生境的上述多样性指数与CI无显著关系（P>0.05）;各生境的植物多样性指数均与NOS无显著相关性（P>0.05）。本研究表明,从水生到中生生境,若尔盖地区的植物多样性呈增加趋势,但植物多样性与物种竞争强度和生态位重叠度的关系较复杂。本研究结果有助于理解若尔盖高原植物多样性的形成机制。     

南麂列岛潮间带大型底栖动物群落优势种生态位

为了解南麂列岛潮间带大型底栖动物的群落特征及其物种间相互作用情况,于2012年5月至2013年2月对南麂列岛保护区内的12个资源位点(潮间带3个潮区的4个季节采样)进行了调查。共采集和鉴定出大型底栖动物354种,其中,18个优势种分别隶属于3门5纲12科。通过对优势种生态位的宽度、重叠度和相似比例的分析,发现:1)带偏顶蛤Modiolus comptus、条纹隔贻贝Septifer virgatus和异须沙蚕Nereis heterocirrata的生态位宽度较宽,均大于0.9;白条地藤壶Euraphia withersi和白脊藤壶Fistulobalanus albicostatus的生态位宽度则较窄,均小于0.5。2)各优势种群的生态位重叠度较低而生态位相似比例较高,生态位宽度值较高的物种对其他物种的生态位重叠值和生态位相似比例也较高,反之则较低。3)Bray-Curtis相似性聚类分析和非度量多维尺度排序(NMDS)结果表明,这些优势种基本属于同一生态类群,没有表现出明显的群落差异。经分析,潮间带大型底栖动物各优势种生态位宽度的分化是由于其对环境的适应能力和迁移能力的不同所导致的,而生态位重叠度较低情况的出现主要是由于各物种占据潮间带上不同的潮区,减小了种间竞争的压力。     

洮河自然保护区大峪沟林区紫果云杉群落木本植物种群生态位特征

基于群落调查数据,以样地代表多种资源的综合状态,物种重要值作为生态位的计测指标,利用Levins和Shannon生态位宽度,Schoener生态位相似和Pianka生态位重叠对洮河自然保护区大峪沟林区的紫果云杉群落木本植物种群生态位进行定量研究。结果表明：紫果云杉群落乔木层共有树种8种,隶属于4科6属,紫果云杉占绝对优势,岷江冷杉为次优势种;灌木层共有植物50种,隶属于16科25属,忍冬科的蓝靛果、葱皮忍冬和唐古特忍冬等以及蔷薇科的峨眉蔷薇和银露梅等构成了灌木层的主体,紫果云杉幼苗优势不明显,但生态位宽度最大。本研究表明,生态位宽度受物种生态特性及其分布和生境共同影响,重要值大的物种生态位宽度一般较大,生态位宽度大的物种之间生态位相似性和重叠性一般较大,并与其它物种重叠的概率高、重叠程度大,生态位宽度小的物种集中出现时也会出现较大的生态位重叠,同科或同属的物种间常有较大生态位相似和重叠。生态位宽度反映着种群的扩散潜力,生态位相似反映着群落的稳定性,生态位重叠反映着物种间存在或潜在的竞争程度。紫果云杉在乔、灌木层均有最大的生态位宽度,生态适应性最强,群落结构稳定,具有进一步扩散的可能。     

浙江江山公益林物种种间关系及CCA排序

利用浙江省江山市80个公益林固定小班监测数据,基于生态位理论、种间联结、CCA排序方法对研究区内群落优势种种间关系及其与环境的关系进行研究。结果表明:江山市公益林群落中杉木、檵木、紫萁分别在乔木、灌木、草本层中占优势地位;石栎与青冈、隔药柃与山苍子、蕨与海金沙的生态位重叠指数值分别在乔、灌、草本层中最大;而CCA协变量矩阵偏典范对应分析说明物种分布主要受海拔、坡度、坡向(光照强度)以及腐殖质厚度的影响,总体上可以对89.44%的环境因子进行解释。并且还表明,生态位宽度较大的物种其生态位重叠值较大,并在CCA排序图物种集中区分布。反之,生态位重叠较小,在CCA排序图中将偏离物种集中区;除此之外,在CCA排序图上,物种间的距离与其生态位重叠值的大小及种间联结均有密切的关联,若未存在显著的联结性,随物种间的生态位重叠值越高,其在CCA排序上的距离越近,若存在显著联结性,则正相关缩小距离,负相关拉大距离。     

北部湾北部生态系统结构与功能——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K-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。     

Niche characteristics of rodents by diverse disturbance in Alashan desert, Inner Mongolia, China

Four diverse disturbance types, namely, farmland, rotationally grazed grassland, overgrazed grassland and forbidden grazing grassland, were identified in the Alashan desert region of Inner Mongolia. Rodents were sampled in April, July and October in 2002 and 2003 using the trap-day method. Their spatial and temporal niches among the four disturbance types were assessed using the Shannon-Wiener niche breadth index and the Pianka niche overlap index. The Shannon-Wiener niche breadth index was the highest for Allactaga sibirica and Meriones meridianus (0.925 and 0.908, respectively), intermediate for Cricetulus eversmanni, Phodopus roborovskii and Citellus dauricus (0.789, 0.782 and 0.711, respectively), and lowest for Cardiocranius paradoxus (0.003). The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000, suggesting their spatial niche overlapped almost completely. Conversely, the spatial niche overlap index for Meriones unguiculatus, Cardiocranius paradoxus, and Salpingotus kozlovi was zero, thus indicating a complete absence of competition among them. In addition, the temporal niche breadth and overlap indices varied greatly in relation to disturbance types and season. The level of temporal niche overlap in spring and autumn was low while in summer it was high. For all disturbance types and for each season, the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest. __________ Translated from Acta Ecologica Sinica, 2005, 25(10): 2,637–2,643 [译自: 生态学报]     

乌鲁木齐达坂城山区地衣生态位特征的研究

为揭示达坂城山区地衣对生境资源的利用状况及竞争程度,该研究在野外设置30个样方并调查其物种盖度数据,利用生态位宽度、生态位重叠指数及排序分析,探讨达坂城山区地衣的生态位特征及环境影响因子。结果表明:(1)达坂城山区生态位最宽的为丽黄鳞衣(Rusavskia elegans)和内卷野粮衣(Circinaria contorta),对不同环境具有较强的适应性,其他地衣物种生态位宽度较窄,对环境资源利用程度低。(2)物种间生态位重叠值整体偏低,生态位重叠值较高的物种对极少,地衣物种生态位分化程度高,物种间竞争不激烈。(3)生态位较宽的物种与多数物种之间都存在生态位重叠,但重叠值较低; 一些生态位较窄的物种与其他物种之间的生态位重叠值较高; 生态位重叠和生态位宽度之间并无直接的线性关系。(4)地衣物种沿海拔梯度分布具有差异,海拔、光照强度、湿度、风速和人为干扰是本地区地衣群落物种生态位特征差异的主导环境因子。综上所述,达坂城山区地衣物种由于生境资源的竞争占据各自独特的生态位,形成了生态位的分化,群落较为稳定,沿海拔梯度的生境条件差异是物种差异分布的重要原因。该研究可为地衣群落构建研究提供理论依据,并对该地区地衣物种的多样性和生境保护具有重要意义。     

古浪县北部荒漠植被主要植物种的生态位特征

利用Shannon-Wiener生态位宽度公式和Pianka生态位重叠公式,计测分析了甘肃省古浪县北部荒漠植被主要植物种在不同植被演替阶段的生态位宽度和生态位重叠。结果表明:在流动沙地上花棒的生态位宽度最大,其次是沙蒿;在半固定沙地上白刺的生态位宽度最大;在固定沙地上,不论是封育植被还是未封育植被中均是花棒的生态位最宽。同一植物种的生态位随着植被演替阶段的变化而发生变化,这种变化反映了不同演替阶段下的植被恢复效果。优势种的生态位重叠大,生态位宽的物种对重叠值也大,相同物种对在不同演替阶段的生态位重叠不一致。有些物种生态位宽度窄,但重叠值大,是由荒漠植被区物种分布存在生境斑块现象造成的。     

Micro-habitat niche differentiation contributing to coexistence of Eucryptorrhynchus scrobiculatus Motschulsky and Eucryptorrhynchus brandti (Harold)*

Temporal, spatial, and trophic niche differentiation usually occurs among species living in similar habitats which can reduce interspecific competition under limited resources. Eucryptorrhynchus scrobiculatus and Eucryptorrhynchus brandti are sympatric and closely related species and are host-specific to Ailanthus altissima (Mill.) Swingle in China. However, the possibility of niche differentiation between the two species is not clear. Therefore, we investigated the density of the two weevils temporally, spatially, and trophically (plant parts of A. altissima) at Lingwu farm and Haojiaqiao town, Lingwu city, Ningxia Hui Autonomous Region. No differences were found in temporal Levin’s niche breath index values ranging from 3.74 to 3.95 and temporal Pianka’s niche overlap values (0.98–0.99). There was little differentiation in the vertical spatial niche. The vertical distribution of E. scrobiculatus was mainly located from 0?cm (ground) to over 250?cm on tree-of-heaven. Eucryptorrhynchus brandti was found predominantly from 0.1 to 50?cm to over 250?cm on tree-of-heaven. The overlap of the cardinal direction spatial niche was 0.90–0.98, indicating no significant overlap in the cardinal direction at Lingwu farm and Haojiaqiao town. Significant differentiation of trophic niche occurred with E. scrobiculatus feeding on 1-year-old branches, perennial branches, and petioles, while E. brandti feed on the stem.     

Niche characteristics of rodents by diverse disturbance in Alashan desert,Inner Mongolia,China

Four diverse disturbance types,namely,farmland,rotationaUy grazed grassland,overgrazed grassland and forbidden grazing grassland,were identified in the Alashan desert region of Inner Mongolia.Rodents were sampled in April,July and October in 2002 and 2003 using the trap-day method.Their spatial and temporal niches among the four disturbance types were assessed using the Shannon-Wiener niche breadth index and the Pianka niche overlap index.The Shannon-Wiener niche breadth index was the highest for Allactaga sibirica and Meriones meridianus (0.925 and 0.908,respectively),intermediate for Cricetulus eversmanni,Phodopus roborovskii and Citellus dauricus (0.789,0.782 and 0.711,respectively),and lowest for Cardiocranius paradoxus (0.003).The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000,suggesting their spatial niche overlapped almost completely.Conversely,the spatial niche overlap index for Meriones unguiculatus,Cardiocranius paradoxus,and Salpingotus kozlovi was zero,thus indicating a complete absence of competition among them.In addition,the temporal niche breadth and overlap indices varied greatly in relation to disturbance types and season.The level of temporal niche overlap in spring and autumn was low while in summer it was high.For all disturbance types and for each season,the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest.     

普陀山主要植物种生态位特征

利用样地调查方法,以物种重要值作为资源状态指标,应用Levins生态位宽度公式和Levins生态位重叠公式对普陀山主要植物种进行了生态位宽度和生态位重叠计算。结果表明:普陀山主要植物群落中,青冈(Cyclobalanopsis glauca)、茶(Camellia sinensis)、薹草(Carex tristachya)的生态位宽度分别在乔、灌、草本层中占有优势地位;而且,各层植物种之间有着不同程度的重叠,表现为草本层>乔木层>灌木层;总体上,各植物种的生态位重叠较小,生态位分化明显,资源利用方式分化较大;分布频度是影响植物种生态位宽度、生态位重叠大小的主要因素之一,分布频度越大,则生态位宽度越大,与其他植物种形成生态位重叠的机率也越大。     

Are howler monkey species ecologically equivalent? Trophic niche overlap in syntopic Alouatta guariba clamitans and Alouatta caraya

According to the principle of competitive exclusion, niche differentiation allows the stable coexistence of closely related species. We analyzed dietary profile and diversity, and dietary overlap between syntopic brown howlers (BR; Alouatta guariba clamitans) and black and gold howlers (BLG; A. caraya) in the Atlantic Forest of NE Argentina, with the objective of evaluating the degree of trophic niche overlap and potential interspecific competition for food. During 12 months, we collected data on feeding behavior of two groups of each howler species using the scan sampling method, together with data on food availability. Both at the group‐ and species‐level, we analyzed feeding behavior in terms of monthly percentages of time spent feeding on each food type and specific food item, dietary diversity (Shannon index H′), and we estimated dietary overlap using the percentage index and the Morisita–Horn index (C_H). Across months, both howlers showed species‐specific preferences for certain food items, and BLG had a more diverse diet (mean±SE, H′=2.77±0.08) than BR (H′=2.39±0.09). However, diets of both species overlapped extensively (percentage index=45.64±2.97%; C_H=0.6±0.05) and diets of conspecific groups did not overlap more than diets of groups of different species. Given their high degree of trophic overlap, syntopic BR and BLG meet one of the conditions necessary for interspecific food competition to occur. Although at present we lack direct evidence for interspecific competition in these howler species, we conclude that high levels of niche overlap may have an important role in maintaining the essentially parapatric distribution of howler species throughout the Neotropics. Am. J. Primatol. 72:173–186, 2010. © 2009 Wiley‐Liss, Inc.     

What makes a plant species specialist in mixed broad-leaved deciduous forests?

Knowledge about relationships between specialization degree of species, i.e. the width of their realized niche and functional traits, may have important implications for the assessment of future population developments under environmental change. In this study, we used a recently introduced method to calculate ecological niche widths of plant species in mixed broad-leaved deciduous forests and to investigate the dependence between niche widths of plants and their functional traits and Ellenberg indicator values. The research is based on a dataset of 4556 phytosociological relevés of mixed broad-leaved deciduous forests in Slovenia. We calculated theta indices for 326 species, which ranks them along a continuous gradient of habitat specialization. For 272 species, we compiled 26 functional traits and Ellenberg indicator values. We found some significant correlations between theta indices of species and their functional traits and Ellenberg indicator values; habitat specialists thrive primarily on the highest altitudes, on colder, dry sites and achieve the age of first flowering later than generalists. They also have smaller seed diameter, lower leaf dry matter content, lower mean canopy height and bigger specific leaf area than generalists. Two species groups, chamaephytes and spring green species, are particularly characterized as specialist species. The added value of our work is in complementing the knowledge about the niche differentiating along different environmental gradients and species coexistence in mixed broad-leaved deciduous forests.     

基于两个不同资源轴上苔藓植物生态位分析

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。     

岩溶穴居性陆氏石山苣苔群落物种组成与生态位分析研究

根据对陆氏石山苣苔模式产地的实地调查与取样,采用定量分析的方法,研究了其模式产地草本植物群落中重要值排名前20的物种优势度、生态位宽度、生态位重叠值以及环境土壤肥力值。结果表明:(1)陆氏石山苣苔在其模式产地中具有明显的优势度,且在Levins、Hurblert生态位宽度指数测度下均排位第二,表明对原生环境中资源的利用程度高,但Pianka生态位重叠显示当产生竞争关系时陆氏石山苣苔总是处于竞争劣势,竞争能力薄弱。(2)岩溶洞穴环境中不同空间上的环境资源存在明显差异,导致物种间的生态位重叠值与种间关系的复杂性,需依据物种的生物学特性和对环境的需求进行区别研究。(3)陆氏石山苣苔模式产地的资源环境因素彼此之间存在一定的相互关系,这构成了一种保护机制,从而缓解了陆氏石山苣苔因其自身竞争力薄弱产生的生存压力,建议后期工作中应优先加强对其环境的保护。     

烟台近海浮游动物优势种空间生态位研究

根据2018年春、夏季烟台近海海域的调查资料,以浮游动物优势种(类)为研究对象,运用Levins公式和Pianka指数分析了浮游动物优势种(类)的生态位宽度和生态位重叠程度,采用冗余分析(RDA)研究了影响浮游动物优势种(类)空间生态位分化的主要因素。研究结果表明,浮游幼虫和桡足类是烟台近海浮游动物群落结构的主要组成群体,春、夏季浮游动物优势种(类)更替率为73.33%。依据烟台近海浮游动物优势种(类)的生态位宽度值,可将其划分为广生态位、中生态位和窄生态位三大类群,广生态位种类为浮游动物优势种(类)的主要构成群体,春季代表种类有短角长腹剑水蚤(Oithona brevicornis)、拟长腹剑水蚤(Oithona similis)等,夏季代表种类有小拟哲水蚤(Paracalanus parvus)、克式纺锤水蚤(Acartia clausi)等。生态位重叠指数与物种分布的环境位点的重合情况密切相关,广生态位种类之间的生态位重叠程度要高于窄生态位种类与其他种类之间的生态位重叠程度。RDA分析表明,春季影响浮游动物优势种(类)空间生态位分化的主要因素为海水温度、盐度和无机氮(DIN),夏季为海水盐度、叶绿素a(Chl a)、无机氮(DIN)和活性磷酸盐(PO_4-P)。     

舟山长白海域主要游泳动物生态位及其分化研究

基于2016年10月（秋季）和2017年4月（春季）舟山长白海域的渔业资源调查数据,运用生态位宽度、生态位重叠及冗余分析等方法,研究了主要游泳动物的生态位,种间生态关系及生态位分化。结果显示：春、秋季主要游泳动物分别11种与8种,两季生态位宽度值差异均较大,其中春季广生态位种、中生态位种均为3种,而秋季均为2种,窄生态位种分别为5种与4种。相对重要性指数（IRI）与生态位宽度值（B_i）之间呈显著正相关。生态位重叠程度不均衡,秋季主要游泳动物的生态位重叠程度较高,O_ik > 0.6的种对数占总种对数的42.86%;春季的重叠程度较低,仅占总种对数的21.82%。RDA分析得出温度、盐度为影响主要游泳动物分布的直接因素,而溶解氧、悬浮物和pH等则为重要因素,主要游泳动物在这些资源维上存在生态分化现象。综上,分布在毗邻杭州湾口且位于著名的岱衢洋的主要游泳动物种类总体营养级较低却生态宽度值较大,大黄鱼（Larimichthys crocea）、黄姑鱼（Nibea albiflora）等一些传统的高营养级、典型特色经济种类却沦为生态位宽度极小的一般种或少有种,群落种类显著减少,资源量下降,群落结构与功能退化,稳定性下降。因此,加强游泳动物资源修复、保护与管理十分迫切且具有重要意义。