共查询到20条相似文献,搜索用时 15 毫秒
1.
云南温泉数量多,分布广,可划分为低温温泉、温泉、热泉和沸泉4种类型。生活在这些温泉中的蓝藻不仅群落类型不同,而且蓝藻区系与西藏、四川、印度等热带和亚热带地区具有一定的相似性。本文报道云南温泉蓝藻89种,分录于3纲4目7科21属。 根据不同温泉类型的生态环境,初步分析了温泉蓝藻的群落结构、区系组成、分布特点,并对生物物种多样性和环境因素的关系进行了讨论。 相似文献
2.
Diversity determinants have mostly been evaluated in high diversity areas, leaving behind regions with less species diversity such as drylands. Here we aim to analyze the patterns of plant diversity in tropical drylands in the southern Central Andes, and determine the importance of water, energy, and environmental heterogeneity as diversity determinants of the arid and semi-arid adapted flora. We examined the distribution of 645 native species from lowlands to 6000 m.a.s.l. in the north-western region of Argentina (NWA) and define hotspots of diversity within each NWA ecoregion. Diversity is concentrated in regions of middle elevation with intermediate values of water and energy, at the transition between arid and semi-arid regions. Furthermore, we showed that in tropical drylands energy input is as fundamental for plant diversity as water input is and, we found that the effects of these variables varied with elevation and, also with aridity. Water variables had the strongest effect on the flora in the arid high Andean ecoregions, where an increase in precipitation during the growing season stimulated species diversity. Energy only became more important than water when the arid adapted flora entered the low and semi-arid regions where energy increments reduce species diversity. Our analysis provides strong quantitative support for climate variables as the main determinants of plant diversity across different ecoregions of the southern Central Andes. Given the present climate change events, knowing how these variables affect the distribution of the arid adapted flora is crucial for planning strategies for achieve their present and future conservation. 相似文献
3.
The orchid flora of the Iberian Peninsula is relatively well known, but its biogeographical and diversity patterns have until now remained unanalysed. This work compares the richness of this flora with that of 27 other territories in different continents and at different latitudes, with the aim of establishing whether it is richer or poorer than might be expected. Latitude was found to be an excellent predictor of regional orchid species richness. With 122 taxa, the orchid flora of the Iberian Peninsula is more or less as diverse as that of other Mediterranean areas of similar latitude (e.g. France, Greece or Italy), but more diverse than other European or indeed North African orchid floras. In this study, the Iberian orchid species were assigned to eight monophyletic clades and the global distribution of these are mapped to establish continental affinities between the floras. A recent floristic account on the Iberian orchids was also used to assign the orchid taxa to habitats, and the relationship between the number of endemisms and their habitats was analysed. The patterns of endemism differed in different habitats. Very high levels of endemism were found in habitats peculiar to the Mediterranean Basin, indicating the relict status of its orchid flora. 相似文献
4.
The increasing urbanization of rural areas leads to a strong development of horticultural flora, which is the main source of alien and invasive plants. In order to assess the pool of cultivated species under different urbanization pressures, the diversity and distribution of horticultural flora were studied in 120 Mediterranean gardens belonging to three housing density types. The results showed a great richness and heterogeneity of this flora, and similarities in species composition between gardens of the same housing density types. Twenty-four percent of the cultivated species are well adapted to the Mediterranean climate, and 21 species known to be invasive on the French territory have emanated from gardens. Inventorying areas adjoining gardens would be useful in identifying escaped garden plants and to assess the associated risks for biological diversity. The results also suggested a detailed analysis of the influence of social, economic and regional factors on planting practices, in order to identify the drivers of these original floral patterns. 相似文献
5.
目的检测不同程度颅脑疾病患者肠道菌群分布情况, 探讨患者肠道菌群分布与疾病的关系, 为该类患者的治疗提供参考。 方法通过MiSeq PE2x300 bp高通量测序技术对21例重度颅脑损伤患者(G1组, GCS≤8分)和14例轻度颅脑损伤患者(G2组, GCS > 8分)粪便样本中细菌的16S rRNA基因V3-V4可变区进行定性分析, 并对两组患者肠道菌群进行生物学分类比较、多样性分析和组间物种差异分析。 结果两组患者肠道菌群多样性差异无统计学意义(均P > 0.05)。G1组患者肠道厌氧球菌属(Anaerococcus)、埃希菌-志贺菌属(Escherichia-Shigella)、链球菌属(Streptococcus)、肠球菌属(Enterococcus)、棒状杆菌属(Corynebacterium)数量高于G2组(均P < 0.05)。 结论颅脑疾病患者肠道菌群紊乱, 其肠道菌群丰度及多样性显著下降, 有害菌数量升高, 有益菌数量下降。 相似文献
6.
全球气候变化与人为活动等因素导致的生物多样性丧失,引起了全球各界对生物多样性保护的高度关注。传统生物多样性保护主要对物种、特有种、受威胁物种的种类组成及其分布模式开展研究,忽视了进化历史在生物多样性保护中的作用。云南是全球生物多样性热点地区的交汇区,生物多样性的保护历来受到广泛关注,为了更好地探讨云南生物多样性的保护措施,该研究以云南被子植物菊类分支物种为研究对象,基于物种间的演化关系,结合其地理分布,从进化历史的角度探讨物种、特有种、受威胁物种的种类组成及系统发育组成的分布格局,并整合自然保护地的空间分布,识别生物多样性的重点保护区域。结果表明:云南被子植物菊类分支的物种、特有种及受威胁物种的物种密度与系统发育多样性均显著正相关;通过零模型分析发现,由南向北标准化系统发育多样性逐渐降低;云南南部、东南部、西北部是云南被子植物菊类分支的重点保护区域,加强这些区域的保护,将最大化地保护生物多样性的进化历史和进化潜能。由此可见,融合进化历史信息的植物多样性格局分析不仅有助于更加深入地理解植物多样性的形成与演变,也为生物多样性保护策略的制定提供更多的思路。 相似文献
7.
利用大尺度的植物分布信息结合地理信息系统和数理统计分析,探讨了云南种子植物多样性的地理分布格局和多样性分化特点。结果表明,从科到属和种,植物多样性和区系分化强度的数据集离散程度均呈递增趋势。相对属和种而言,科的多样性的空间分异和高值区域并不明显,这可能与科、属、种所代表的不同地质历史时期有关;南部地区属和种的多样性明显高于除滇西北以外的大部分地区。种的多样性分布中心主要集中在滇西北地区、云南南部地区、哀牢山、无量山地区和昆明地区,这可能与生境异质性和热量条件有关。相对科而言,属的区系分化强度的空间分异更为明显,并与物种多样性的分布格局比较接近,暗示着植物多样性与区系分化之间的密切联系。相对科而言,属的区系分化中心高值区域更为明显。总体上,云南地区植物多样性的分布格局及其分化可能与其生境、热量条件和地质历史有关。 相似文献
8.
Global declines in biodiversity, together with widespread degradation of ecosystem services, have led to urgent calls to safeguard. Humans maintain plants around their houses to increase their quality of life. In the present study, 90 and 30 plots of 50 m 2 each were studied in urbanised and rural areas in Cameroon. In each plot, vascular plant species were identified and their coefficient of abundance–dominance was determined. Different diversity indices were calculated to compare the flora of urbanised and rural areas as well as the distribution of plants. A total of 119 species belonging to 95 genera and 45 families were sampled. Shannon–Weaver diversity index, Pielou and Sheldon values vary when taking into account not only erected or wooded plants, but also herbs and erected or wooded plants. Plots near houses in urban areas comprised weeds, ornamentals and fruits, whereas in rural areas medicinal or edible plants dominated. Based upon the results, we conclude that the use of plants as food, medicinal resources or for other purposes, might be helpful for biodiversity conservation, ecosystem services, the management of resources and to fight poverty. However, the composition of the flora is likely to change as urbanisation proceeds. 相似文献
9.
为了解日益恶化的喀斯特环境下叶附生苔类植物的分布状况,对广西中越边境喀斯特地区叶附生苔类植物多样性展开调查。结果表明,广西中越边境喀斯特地区有叶附生苔类植物5科15属43种,其中,九洲疣鳞苔(Cololejeunea yakusimensis)、巴氏薄鳞苔(Leptolejeunea balansae)、斯氏唇鳞苔(Cheilolejeunea streimannii)、麦氏细鳞苔(Lejeunea micholitzii)、巨齿细鳞苔(L.kodamae)和纤细细鳞苔(L.exilis)为广西苔藓植物新记录。该地区叶附生苔类植物区系具有热带性质和东亚分布特点。与邻近地区比较,该地区叶附生苔类植物与贵州茂兰的亲缘关系和区系关系最紧密。该地区叶附生苔类植物分布随海拔增加呈增加趋势。那坡老虎跳保护区、龙州和宁明弄岗保护区以及靖西龙邦镇风水林是叶附生苔类植物分布最丰富的地区,因此,建议应对这些地区的叶附生苔类植物进行优先保护。 相似文献
10.
Effective conservation of biodiversity in the face of increasing human impacts and global environmental changes requires accurate measurement of key trends and alternative management actions at landscape scales. Past ecological conditions are certainly important key factors in determining the present species diversity patterns and the inclusion of such factors (e.g. by historical cartographic data) can dramatically improve the predictive power of ecological models. In this paper we applied a retrogressive approach with the aim of simulating secondary forest regrowth effects on plant species diversity using present field data and historic land-use maps. The field data from an extensive sample were here used to model the temporal species richness change among the forest areas in the last 60 years. In order to rebuild the past species pool matrix using present field data and historical land use map, we applied a nearest neighbour selection using spatial query. Species-based rarefaction curves were derived for the two dates (1954 and 2010); the two datasets have been interpolated using inverse distance weighted algorithm, obtaining two maps showing the distribution of plant species richness for the two dates.The results showed that the cessation of human pressure on semi-natural areas and the consequent forest recovery, resulted in a decrease of vascular plant as a woodland flora replaces the open habitats flora. This study also showed that secondary forest regrowth and its effect on plant species diversity may be revealed by a retrogressive analysis, which represent a valid support in case of high uncertainty or absence of historical data. 相似文献
11.
肠道菌群在维持宿主免疫和消化系统功能方面发挥着重要作用,肠道菌群的多样性和丰富度是衡量宿主健康状况的重要生理指标。性激素对动物生长发育发挥重要作用,但其对肠道菌群构成影响的相关实验研究相对较少。本研究以模式生物小鼠(Mus musculus)为对象,探究性激素的变化对小鼠肠道菌群构成的影响。采用外科手术方式建立小鼠去势模型,通过16S r RNA高通量测序技术,研究性激素对小鼠肠道菌群构成的影响。研究结果表明,雌性小鼠和雄性小鼠去势后,性激素水平显著下降。肠道菌群在门水平上,正常小鼠和去势小鼠肠道细菌群落均由拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、埃普西隆杆菌门(Epsilonbacteraeota)、髌骨细菌门(Patescibacteria)、放线菌门(Actinobacteria)、软壁菌门(Tenericutes)、脱铁杆菌门(Deferribacteres)、酸杆菌门(Acidobacteria)和蓝藻细菌门(Cyanobacteria)组成,主要菌群为厚壁菌门和拟杆菌门物种,两门占物种相对丰度百分比... 相似文献
12.
对植物多样性垂直分布格局及其维持机制的研究可以有效揭示植物物种多样性分布特征及其环境影响因子。本文通过野外调查、查阅标本并结合相关文献资料,对天山南坡中段种子植物区系沿海拔梯度的分布格局进行了系统研究。结果显示,在大区域尺度上,科属种的物种丰富度随海拔升高均呈先增加后减少的趋势,且最高值出现在中低海拔1900~2000 m处;不同生活型植物沿海拔梯度的变化格局有所不同,其中,乔木、一年生草本、藤本及寄生植物表现出随海拔升高物种丰富度逐渐降低的趋势,灌木、多年生草本及二年生草本植物物种丰富度则呈先增加后减少的变化趋势;从植物区系地理成分来看,世界分布所占的比重沿海拔梯度升高呈先增加后减少的趋势;温带地理成分所占的比重沿海拔梯度升高呈缓慢上升趋势;古地中海地理成分所占的比重沿海拔梯度升高呈先增加后减少然后再增加的变化趋势;热带地理成分所占的比重沿海拔升高呈逐渐下降的趋势;东亚地理成分所占的比重沿海拔梯度升高呈先增加后减少然后再增加的变化趋势。对该分布格局与当地干旱的气候条件及海拔梯度上热量和水分条件的变化相适应。 相似文献
13.
目的 比较首发抑郁症患者与健康人群肠道菌群的差异,探讨抑郁症患者肠道菌群和抑郁症状间的关系,为抑郁症的发病机制研究及治疗提供一定的理论依据。 方法 选择2019年10月至2020年9月我院收治的首发抑郁症患者及健康人群为研究对象,分为抑郁组(n = 23)和健康组(n = 31)。对研究对象肠道菌群16S rRNA基因中V4−V5区域片段进行基因测序,使用汉密尔顿抑郁量表对两组对象抑郁症状进行评估。检测两组对象肠道菌群α多样性、β多样性和组间差异。 结果 首发抑郁症患者与健康人群肠道菌群多样性差异无统计学意义(均P>0.05)。两组对象肠道拟杆菌门和拟杆菌纲的相对丰度差异有统计学意义(均P<0.05)。两组对象芽胞杆菌目等的相对丰度差异有统计学意义(P<0.05)。在属水平和种水平上,两组对象分别有28个菌属和40个菌种的丰度差异有统计学意义(均P<0.05)。LEfSe分析显示,拟杆菌科、艾克曼菌科等10种菌科是造成两组对象肠道菌群差异的主要细菌。 结论 首发抑郁症患者与健康人群肠道菌群多样性未发现显著差异,但抑郁症患者肠道菌群结构与健康人群相比发生了改变,主要体现在拟杆菌属等细菌在抑郁症患者肠道中的相对丰度显著上升。 相似文献
14.
The Balkan Peninsula is recognized as an important centre of plant diversity. Despite the fact that Croatia contains more than 50% of all Balkan species of vascular flora, the knowledge of the spatial distribution, α-diversity and relation to the conservation efforts have never been summarized and presented. A spatial analysis was performed on several data-sets containing a number of records and a number of species per grid cell. Results show that the Croatian flora consists of 4507 species and 1159 subspecies. The residuals around the linear regression used as a measure of the species richness indicate that Croatia had the highest residual value among the 40 European countries sampled and highest stress on the biodiversity value of the Apennine, the Iberian and the Balkan peninsulas. On the basis of half a million findings and their spatial distributions, we observed that within one grid cell (35 km 2) 542 species could be expected. A number of records based on the herbarium specimens, literature and field observation and related spatial distribution were discussed. The spatial distribution of α-diversity indicates that the national hot spots were more consistent with the important plant areas network than with the network of officially protected areas. 相似文献
15.
湖北植被尤其是鄂西地区,在近代以来备受植物学家的关注。该研究基于植物标本、文献资料与野外调查成果,整理出湖北兰科植物名录,结合湖北的地形与气候特征分析了湖北兰科植物的分布格局、区系及多样性特征。结果表明:湖北兰科植物主要分布在西南、西北、东北及东南部山区,以鄂西山地最为丰富,中南部江汉平原最少,900~1 200 m中海拔地段丰富度最高;物种多样性由南至北、由西至东呈递减趋势,鄂西南与鄂西北之间具有最大相似性;除拟兰亚科(subfam.Apostasioideae)外的5个亚科湖北均有分布,计有15族54属141种,单种属和寡种属分别占总属数的50.00%和33.33%;湖北兰科植物东亚分布成分占40.43%,中国特有种占总种数的41.84%,东亚区系主体突出,中国特有成分所占比例较大,其中中国—日本成分占优势;温带属性较强,亚热带向温带过渡特征明显,有25个热带分布属及27个温带分布属,热温比为0.93,种级水平的热带分布类型占8.51%,温带分布类型占91.49%;一些稀缺种在台湾与湖北的间断分布,表明两者植物区系有较强的关联性;湖北兰科植物区系与西南及横断山区联系密切,是与东部地区植物区系交流的中转站。 相似文献
16.
Aim To establish how well the terrestrial flora of the Antarctic has been sampled, how well the flora is known, and to determine the major patterns in diversity and biogeography. Location Antarctica south of 60° S, together with the South Sandwich Islands, but excluding South Georgia, Bouvetøya and the periantarctic islands. Methods Plant occurrence data were collated from herbarium specimens and literature records, and assembled into the Antarctic Plant Database. Distributional patterns were analysed using a geographic information system. Biogeographical patterns were determined with a variety of multivariate statistics. Results Plants have been recorded from throughout the Antarctic, including all latitudes between 60° S and 86° S. Species richness declines with latitude along the Antarctic Peninsula, but there was no evidence for a similar cline in Victoria Land and the Transantarctic mountains. Multi‐dimensional scaling ordinations showed that the species compositions of the South Orkney, South Shetland Islands and the north‐western Antarctic Peninsula are very similar to each other, as are the floras of different regions in continental Antarctica. They also suggest, however, that the eastern Antarctic Peninsula flora is more similar to the flora of the southern Antarctic Peninsula than to the continental flora (with which it has traditionally been linked). The South Sandwich Islands have a flora that is very dissimilar to that in all Antarctic regions, probably because of their isolation and volcanic nature. Main conclusions The Antarctic flora has been reasonably well sampled, but certain areas require further floristic surveys. Available data do, however, allow for a number of robust conclusions. A diversity gradient exists along the Antarctic Peninsula, with fewer species (but not fewer higher taxa) at higher latitudes. Multi‐dimensional scaling ordination suggests three major floral provinces within Antarctica: northern maritime, southern maritime, and continental. Patterns of endemism suggest that a proportion of the lichen flora may have an ancient vicariant distribution, while most bryophytes are more recent colonists. 相似文献
17.
We analysed the geographic distribution of 645 species of marine benthic algae along the Atlantic coast of Europe and Pacific coast of temperate South America to test for the existence of an association between geographic range size and latitude (Rapoport's Rule) and for three key components of the explanations offered for it. We found that species in high diversity areas are characterized by small geographic ranges and by low specific growth rates as compared to species with large geographic ranges, thus supporting the Rapoport-rescue hypothesis. However, the pattern is not related to species' tolerances, to abiotic conditions or to climatic variability. Further, the inverse latitudinal diversity pattern shown by the marine algal flora of temperate Pacific South America, and the opposite patterns shown by tropical and subantarctic species within this flora, stressed that small geographic ranges are linked to high diversity areas in general, and not only in relation to the pole to tropic species diversity gradient. 相似文献
18.
以大尺度的物种分布信息为基础,对滇西北地区种子植物物种多样性的地理分布格局及其与植物区系分化之间的关系进行分析.结果表明:(1)滇西北地区的种子植物物种多样性从南到北呈递增趋势;(2)无论是在属的水平上,还是在科的水平上,植物区系分化强度从南到北均呈单调递增格局;(3)区系分化强度较大的区域主要集中在地形复杂的北部地区;(4)物种多样性随着区系分化强度的增强而增加;(5)物种多样性地理分布格局的形成可能与滇西北地区的地质历史、地形以及由此引起的植物区系分化有关. 相似文献
19.
青海湖鸟岛地区草地群落共出现种子植物 6 3种 ,隶属 4 3属 ,19科 ,以北温带成分为主 ;从湖滨到典型地带性植被 ,物种多样性指数变化可以分为两大类型 ;随着高度增加 ,物种多样性呈现倒U型变化 ,沿着水平梯度物种多样性基本上逐渐增加。可以分为禾草、豆科固氮植物、非禾本科草类和半灌木功能组 ,物种水平与功能组水平的多样性、均匀度和丰富度相关系数分别为 0 2 79,0 4 36 ,0 0 19,均没有达到显著相关 ,功能组水平的多样性指数具有与物种水平不同的性质 相似文献
20.
The karst landform in southern China is renowned for its high levels of species diversity and endemism. Globally, karst ecosystems are under threat from unsustainable anthropogenic disturbance and climate changes and are among the most threatened ecosystems worldwide. In this study, we used the typical karst endemic genus in southern China, Primulina Hance, as a model to identify areas within the karst landform with high diversity and to investigate congruence between phylogenetic and species‐based measures of diversity. Using phylogenetic information and species distribution data, we measured geographical patterns of diversity with four metrics: species richness (SR), corrected weighted endemism (CWE), phylogenetic diversity (PD), and phylogenetic endemism (PE). Our results revealed a high spatial congruence among SR, PD, and PE, with hotspot areas identified in the Nanling Mountains (i.e., north Guangdong and northeast Guangxi) and southeast Yungui Plateau (i.e., north and southwest Guangxi), whereas the hotspots of CWE are comparatively uniform throughout the geographic extent. The categorical analysis of neo‐ and paleoendemism identified a pattern of mixed neo‐ and paleoendemism in numerous grid cells, suggesting that karst areas in southern China have acted as both “museums” and “cradles” of plant evolution. Conservation gap analysis of hotspots revealed that the majority of prioritized hotspots (>90%) of the genus are outside of protected areas, therefore indicating the limited effectiveness of national nature reserves for the karst flora. Overall, our results suggest that the karst flora merits more conservation attention and SR can be an effective surrogate to capture PD in conservation planning. 相似文献
|