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1.
河南黄河湿地位于黄河中下游,由西向东随地势变化,动植物物种组成及多样性变化复杂。于2011年至2015年对三门峡市、洛阳市以及焦作市的黄河湿地保护区维管植物和哺乳动物进行了全面调查,比较分析了三个区域间动植物多样性的差异,采用非趋势对应分析和聚类分析对物种组成数据进行排序和分类,结果显示:(1)三门峡、洛阳和焦作黄河湿地维管植物分别有130科、493属、1128种及变种,128科、470属、1049种及变种,90科、290属、542种及变种;三门峡黄河湿地哺乳动物有6目、15科、48种,洛阳黄河湿地哺乳动物有7目、18科、61种,焦作黄河湿地哺乳动物有6目、11科、34种;(2)从三门峡黄河湿地经洛阳黄河湿地再到焦作黄河湿地,维管植物多样性降低;(3)三门峡黄河湿地维管植物多样性和哺乳动物多样性与洛阳黄河湿地差异不显著,与焦作黄河湿地差异显著。研究结果丰富了河南黄河湿地保护区植物和动物多样性研究资料,同时也为保护区的保护管理和科研监测提供参考。  相似文献   

2.
Armillaria isolates were collected from a unique forest ecosystem in the Niobrara Valley Preserve in Nebraska, USA, which comprises a glacial and early postglacial refugium in the central plains of North America. The isolates were collected from diverse forest trees representing a unique mixture of forest types. Combined methods of rDNA sequencing and flow cytometric measurements of nuclear DNA content determined that all Armillaria isolates collected from the site were A. gallica.  相似文献   

3.
Aim  African forests are divided by an arid corridor which runs from the Horn of Africa to the Namib Desert. Several forest species occur in the forests of eastern Africa as well as in the Guineo-Congolian forest block. We evaluate the possibility that such species may have crossed the arid corridor along a route through the Kenyan Highlands and down the eastern drainages during climatologically favourable periods in the past.
Locations  Eastern Africa, Ivory Coast.
Methods  We used the termite species Schedorhinotermes lamanianus (Sjöstedt). This species occurs in lowland forests and woodland throughout Africa south of the Sahara. We sampled termites from 12 populations. We evaluated the differentiation between populations using amplified fragment length polymorphisms as well as morphometrical measurements.
Results  Genetic and morphometrical analysis demonstrated substantial differentiation between populations west and east of the arid corridor in Kenya. To the east of this corridor we found an increase of morphological distance with geographical distance. Schedorhinotermes lamanianus occurs not only along the coast but also at isolated locations (e.g. ground-water forests in foothills) within the arid hinterland.
Main conclusions  We interpret these populations as remnants of a wider distribution during wet climatic periods. At these times, populations of S. lamanianus were apparently able to establish along extensive gallery forests protruding into the arid belt of the Kenyan hinterland. There have been no connections between populations of this species east and west of the arid corridor across the Kenyan Highlands.  相似文献   

4.
Butterflies – who is coming, who is going? Immigration routes to Central Europe The majority of butterflies and burnet moths distributed in Central Europe today results from postglacial colonisation of this region mostly from expansions out of the well known Mediterranean refuge areas. The study region was mostly colonised west or east of the Alps, which represent a strong dispersal obstacle. Species being widespread under glacial conditions in Central Europe have retreated under the warm conditions of the Postglacial to the high mountain systems or the Arctic. Therefore, they are mostly restricted to the high altitudes of the Alps in Western Central Europe. Nevertheless, some species have even survived in lowland areas of Central Europe during glacial and inter‐/postglacial conditions, but these species are either better adapted to glacial or to inter‐/postglacial conditions.  相似文献   

5.
广西植物地理的基本情况和基本特征   总被引:5,自引:0,他引:5  
陆益新  梁畴芬   《广西植物》1983,(3):153-165
<正> 广西处于北纬20°54′—36°20′,东经104°28′—112°04′之间。全区总面积23万6千平方公里,约占全国面积的2.46%。本区西靠云贵高原,南部濒临海洋,地跨热带和亚热带。地势东南低、西北高,因而河流主要是由西北向东南流入南海。广西境内群山环绕,在群山之中往往出现一些不大的盆地,在西江干流上亦有若干局部的小平原。广西大部分地区属于古老的地块—华夏陆台,因此,在海拔高度上,除东北和西北部以及中部、东部、东南部的弧形山脉、勾漏山脉和十万大山在500米以上者外,其余地区一般在500米以下,属丘陵地。区内超过2000米的山峰有五座。岩溶地形广泛发育,散布于区内各地,形成千奇百怪的岩溶地貌,构成广西地貌的主要特征之一。  相似文献   

6.
7.
三峡库区消涨带维管植物区系的初步研究   总被引:13,自引:4,他引:9  
三峡库区消涨带是指三峡库区范围内长江进一步充及其支流由于江(河)水水位季节性涨落。导致其沿江(河)两岸土地出现周期性淹没而自然形成的带状区域。该带维管植物区系具有以下特征;植物种类比较丰富,计有维管植物83科,240属,377种,26变种和2变型;地理成分复杂,联系广泛,温带成分占优势;区系组成表现进化性,生活型组成以多年生草本,一年生草本和灌木为主;地方特有成分不多,但中国特有种类比较丰富;带内不同区段物种丰富度有差异。干流多于支流,奉节以东多于奉节以西,带上部多于带中部和带下部;优势现象明显,表征类型丰富。  相似文献   

8.
Runck AM  Cook JA 《Molecular ecology》2005,14(5):1445-1456
Dynamic climatic oscillations of the Pleistocene dramatically changed the distributions of high latitude species. Molecular investigations of a variety of organisms show that processes of postglacial colonization of boreal regions were more complex than initially thought. Phylogeographical and coalescent analyses were conducted on partial sequences of the cytochrome b gene (600 bp) from 64 individuals of Clethrionomys gapperi from North Carolina, Pennsylvania, Minnesota, Idaho, Washington, British Columbia, Northwest Territories, and Alaska to test hypotheses relating to Pleistocene refugia and postglacial colonization routes. Three divergent clades (east, west, central) were identified with highest net divergence (dA = 5.2%) between the eastern and western clades. Populations from the recently deglaciated higher latitudes of Canada and Alaska are closely related to lower latitude populations of the central clade (dA = 1.2%) suggesting recent expansion from this midwestern region. No representatives from the east or west clade were found at latitudes higher than 50 degrees N, indicating that postglacial colonization occurred through a midcontinental route. The high latitude population from the Northwest Territories exhibited demographic patterns and genetic diversity consistent with a stable noncolonizing population. This population is found near the Mackenzie range, where the two continental ice sheets were believed to have coalesced. Molecular variation observed in this population may be the result of leading edge population diversifying in the continental corridor or may reflect the signal of a high latitude refugial population.  相似文献   

9.
This paper presents a numerical analysis of the distribution patterns in Europe and adjoining regions of 242 vascular plant species occurring in the Italian beech forests. The classification of a matrix of species and of 531 Operational Geographic Units (OGUs) led to recognition of 15 different phytogeographic elements (chorotypes). The joint distribution of the species belonging to each chorotype is shown by a chorogram, which is a geographic map obtained by computer processing of the distributional data. Some of the chorograms show the main distributional centers for the beechwood flora in southern Europe: northwestern Balkan Peninsula and eastern Alps, southern Balkan Peninsula, Maritime Alps, northern Apennines, southern Apennines. Only 20% of the species are limited to narrow areas in southern Europe, and were not able to expand considerably their ranges in postglacial times. Migration from the refugia and colonization of vast areas in central and northern Europe led to intensive speciation phenomena, occurring chiefly through the formation of neopolyploid species. Several south European, narrow-ranging species, can be considered as palaeopolyploids with relict character. There is a good relationship between distribution and ecology of the chorotypes.Abbreviations OGU Operational Geographic Unit - OGS Operational Geographic Set - OCS Operational Character Set  相似文献   

10.
In this study, we investigate the mechanisms driving biodiversity in floodplain forests with a comparison of the composition and dynamics in the warm-temperate floodplain forests of the lower Mississippi Valley and the cool-temperate floodplain forests of the lower Wisconsin and Rhine River Valleys. We employ data from original research, as well as from the literature. We compare species, genus, and family diversity across regions with respect to species richness, numbers of species per family and genus, and a similarity index. We examine these results within a historical context, as well as with respect to river-floodplain dynamics. We also compare productivity data and successional stages for each region. We find a lower species, genus, and family richness in the cool-temperate forests of the Rhine compared to the cool-temperate forests of the Wisconsin, a probable result of the lack of available refugia for Rhine species in times of glacial expansion. We find the highest richness in the lower Mississippi Valley, likely a result of climatic factors and the availability of refugia in this region. In each of the regions, floodplain forests are more diverse than their upland counterparts, demonstrating the role of river-floodplain dynamics in maintaining species diversity. Each region maintains a high and relatively similar level of productivity in the floodplain forests. They also experience similar stages of succession, although succession becomes more complex in the warm-temperate forests of the Lower Mississippi.  相似文献   

11.
The schizothoracine Gymnocypris chilianensis is restricted to the Shiyang, Ruoshui and Shule Rivers, listed from east to west, along the northeast edge of the Tibetan Plateau. This distribution provides a valuable system to test hypotheses about postglacial colonization. We used mitochondrial DNA sequence data (a control region and the cytochrome b gene; 1894 bp) to assess the phylogeographic structure of this species based on 278 specimens sampled from throughout the species' entire geographical range. We found three lineages corresponding geographically to the three rivers, suggesting three independent glacial differentiation centers within the northeast edge of the Tibetan Plateau. The phylogenetic analysis suggested that the Shiyang River population forms a lineage that separated from the other populations of G. chilianensis at the basal phylogenetic split within this species. The molecular data further demonstrated a clear pattern of decreasing genetic diversity from the eastern Shiyang River towards the central Ruoshui River and western Shule River lineages, a pattern consistent with sequential western colonization. We therefore propose a phylogeographic scenario for G. chilianensis of a gradual westerly expansion from the Shiyang River population along the northeast edge of the Tibetan Plateau, with subsequent allopatric evolution at approximately 0.37 and 0.05 million years ago (Ma), through at least two glacial maxima. Together with the genetic evidence reported in other species, our findings suggest that this common biogeographic pattern emphasizes the importance of the northeastern edge region of the Tibetan Plateau as a hotspot of genetic diversity for some taxa.  相似文献   

12.
浙江省珍稀濒危植物物种多样性保护的关键区域   总被引:29,自引:0,他引:29  
浙江省植物资源丰富,有野生维管植物215科1196属3283种,其中包含了我国特有属49个,浙江省特有植物约200余种,许多物种十分稀少,并受到严重威胁,亟待保护。但浙江省需优先保护的植物物种的分布并不是均匀的,有些地区的重要保护对象比较集中,对这些地区我们应该给予更多的保护。本文根据维管植物物种多样性、珍稀濒危植物的物种数量及个体数量特征、受威胁状况以及浙江省特有植物的分布情况,提出了浙江省珍稀濒危植物保护的7个关键区域:以西天目山为中心的浙西北山区,以古田山为中心的浙西山区,以九龙山为中心的浙西南山区,以凤阳山-百山祖为中心的浙南山区,以括苍山为中心的浙东山区,以天台山为中心的浙东丘陵,以普陀山为中心的舟山群岛。最后提出了浙江省植物物种多样性保护的几点建议。  相似文献   

13.
Most phylogeographic studies examine organisms that do not have transcontinental distributions and therefore the genetic and temporal effects of barriers across an entire continent cannot be assessed with respect to a single species. We examined the phylogeographic structure, lineage age, and historical demography using sequences from the mtDNA cytochrome b gene of the widespread North American racer (Coluber constrictor), one of the few abundant transcontinental snakes that occurs throughout many diverse biomes. Our results indicate that this complex is comprised of six lineages differing greatly in geographic extent, with the largest (a central US clade) being approximately 26 times greater than the smallest (a lineage restricted to the Florida Panhandle and nearby portions of adjacent States). Most of the six lineages appear to be separated at previously identified genetic barriers for several vertebrates with similar ranges. Lineage diversification in this species began in the late Miocene, separating populations in the Florida Peninsula from the remainder of the US. Diversification of lineages continued throughout the Pliocene and early Pleistocene. Four of the six lineages occur east of the Mississippi River, with only two distinctly young ( approximately 1.5 mya) lineages found west of the Mississippi River (one occurs west of Continental Divide). All methods of demographic inference, including the mismatch distribution, Fu and Li's D and Tajima's D , and Bayesian skyline plots revealed population expansion occurring in the mid-to-late Pleistocene for every lineage, regardless of size or proximity to formerly glaciated areas. Population expansion for lineages found east of the Mississippi River occurred earlier and was much greater than those found west of the River.  相似文献   

14.
The differences in rainfall and temperature between the east and west sides of the northern GaoligongMts. leads to distinct differences in the plant diversity and floristic characteristics between the two sides . Recorded taxa on the east side include 1 475 native species and 192 varieties (or subspecies) belonging to 580 genera in 152 families and for the west side include 1 804 native species and 186 varieties ( or subspecies) belonging to 659 genera in 162 families . Based on the statistics and analysis of families, genera, and species, a comparative floristic study on the seed plants for the east side and the west side of the northern Gaoligong Mts. was carried out. The results are as follows: 1) The present flora on the east and west sides of the northern Gaoligong Mts . have the same floristic origins, but the relative contribution from these different sources has changed through time . The result is that the floristic similarity of families, genera, and species between the east side and the west side has decreased through time; 2) The floristic characteristic of seed plants for the west side has become more greatly influenced by tropical floristic elements than has that of the east side, and the influence by the temperate floristic elements has become less influenced on the west side but greater on the east side; 3) The flora of the west side is more closely linked with that of the eastern Himalayans than is the flora of the east side, and the flora of the east side is more closely linked with the other floras farther to the east. Owing to the obstruct of the Gaoligong Mts. ridge itself, it is seemingly difficult for the species interchange between the two sides of the northern Gaoligong Mts. ; 4) The ecological-geographical environment has made it more conducive to species conservation and the speciation on the west side than on the east side, so the west side is not only a refuge for some ancient floristic elements but also as a cradle of some new species.  相似文献   

15.
We present an analysis of local species richness in neotropical forests, based on a number of 0.1 ha samples of woody plants collected by the late Alwyn Gentry. For each of 69 forests, soils were analysed and climatic data were collated. Using transformed independent variables and interaction terms, multiple regression equations were developed that explained the greatest possible amount of variation in species richness, and the best equations were selected on the basis of regression diagnostics. The best models are presented for (a) all neotropical forests, (b) forests west of the Andes (transandean) and (c) east of the Andes (cisandean), and for various subsets based on elevation and annual rainfall. For the whole dataset, and for most subsets, annual rainfall and rainfall seasonality were the most important variables for explaining species richness. Soil variables were correlated with precipitation — drier forests have more nutrient-rich soils. After the inclusion of rainfall variables, available soil nutrient concentrations contributed little to explaining or accounting for additional variation in species numbers, indicating that tropical forest species richness is surprisingly independent of soil quality. The results are consistent with the hypothesis that plants in mature tropical forests may obtain nutrients through the process of direct cycling, in which mineral nutrients are extracted from litterfall before they enter the soil. The strong relationship between community species richness and rainfall patterns has implications for biodiversity conservation. Wet forests with an ample year-round moisture supply harbour the greatest number of woody plant species and should be a focus of conservation efforts.Died 3 August 1993.  相似文献   

16.
Ecoregions are increasingly being used as a framework for conservation planning. The Mid-Boreal Uplands Ecoregion stretches across Canada from Manitoba to British Columbia. From the perspective of conservation and to understand the dynamics of plant diversity and community composition in a common wetland type, we examined the plant communities and environmental variables in 80 wooded moderate-rich fens within this ecoregion. Regional diversity totalled 273 species, with 86 bryophytes and 187 vascular plants. Total diversity was greatest in Manitoba and decreased in a longitudinal trend west through Saskatchewan and Alberta. This may be related, in part, to orographic precipitation at Manitoba sites and a gradient of growing degree days. Richness of locally rare vascular plants exhibited a clear west to east gradient. Ten species of provincially rare vascular plants were observed across the ecoregion, but without pattern. Ordinations and other analyses revealed distinct plant communities for all three locations, with vascular plant assemblages more discrete than bryophyte assemblages. Bryophyte diversity increased with latitude and longitude, whereas vascular plant diversity decreased. Additionally, elevation, precipitation, surface water alkalinity, water temperature, percent overstory density, and peat organic C played a role in determining species richness and community composition. Overall, species composition and diversity in a single wetland type exhibited continuous change across multiple political jurisdictions at the ecoregion scale. Conservation plans for wetlands at the ecodistrict scale may be preferable.  相似文献   

17.
Understanding how past climate changes affected biodiversity is a key issue in contemporary ecology and conservation biology. These diversity changes are, however, difficult to reconstruct from paleoecological sources alone, because macrofossil and pollen records do not provide complete information about species assemblages. Ecologists therefore use information from modern analogues of past communities in order to get a better understanding of past diversity changes. Here we compare plant diversity, species traits and environment between late-glacial Abies, early-Holocene Quercus, and mid-Holocene warm-temperate Carpinus forest refugia on Jeju Island, Korea in order to provide insights into postglacial changes associated with their replacement. Based on detailed study of relict communities, we propose that the late-glacial open-canopy conifer forests in southern part of Korean Peninsula were rich in vascular plants, in particular of heliophilous herbs, whose dramatic decline was caused by the early Holocene invasion of dwarf bamboo into the understory of Quercus forests, followed by mid-Holocene expansion of strongly shading trees such as maple and hornbeam. This diversity loss was partly compensated in the Carpinus forests by an increase in shade-tolerant evergreen trees, shrubs and lianas. However, the pool of these species is much smaller than that of light-demanding herbs, and hence the total species richness is lower, both locally and in the whole area of the Carpinus and Quercus forests. The strongly shading tree species dominating in the hornbeam forests have higher leaf tissue N and P concentrations and smaller leaf dry matter content, which enhances litter decomposition and nutrient cycling and in turn favored the selection of highly competitive species in the shrub layer. This further reduced available light and caused almost complete disappearance of understory herbs, including dwarf bamboo.  相似文献   

18.
Invader traits (including plant growth form) may play an important, and perhaps overlooked, role in determining macroscale patterns of biological invasions and therefore warrant greater consideration in future investigations aimed at understanding these patterns. To assess this need, we used empirical data from a national‐level survey of forest in the contiguous 48 states of the USA to identify geographic hotspots of forest plant invasion for three distinct invasion characteristics: invasive species richness, trait richness (defined as the number of the five following plant growth forms represented by the invasive plants present at a given location: forbs, grasses, shrubs, trees, and vines), and species richness within each growth form. Three key findings emerged. 1) The hotspots identified encompassed from 9 to 23% of the total area of our study region, thereby revealing many forests to be not only invaded, but highly invaded. 2) Substantial spatial disagreement among hotspots of invasive species richness, invasive trait richness, and species richness of invasive plants within each growth form revealed many locations to be hotspots for invader traits, or for particular growth forms of invasive plants, rather than for invasive plants in general. 3) Despite eastern forests exhibiting higher levels of plant invasion than western forests, species richness for invasive forbs and grasses in the west were respectively greater than and equivalent to levels found in the east. Contrasting patterns between eastern and western forests in the number of invasive species detected for each growth form combined with the spatial disagreement found among hotspot types suggests trait‐based variability in invasion drivers. Our findings reveal invader traits to be an important contributor to macroscale invasion patterns.  相似文献   

19.
Climate is often singled out as the primary range limiting factor at large scales, while other environmental factors, notably soil, are thought to predominate at smaller scales. However, the postglacial migrational lag hypothesis controversially suggests that many species are strongly dispersal‐limited and still expanding from their ice age refugia. We investigated the importance of postglacial migrational lag, climate, and soil as range determinants for 47 widespread forest plant species across nemoral Europe (47.0–60.0°N, west of 24.0°E) using regression modeling, information‐theoretic model selection, multi‐model inference, and variation partitioning. Migrational lag was represented by a measure of accessibility to recolonization from ice age refugia. Twelve species were largely ubiquitous and not analyzed further. For the remaining species, there was strong support for climate, soil, and accessibility to postglacial recolonization. Accessibility accounted for a small to moderate amount of variation, but its model‐averaged regression coefficient was stronger than those for climate or soil for 11 species and the second or third strongest coefficient for an additional 10 species. The resulting odds ratios were greater than one for 33 out of 35 species, i.e. adjusted for climate and soil, prevalence for the far majority of the 35 non‐ubiquitous species increased with increasing accessibility. There were no differences among growth forms in the importance of accessibility. In contrast, compared to non‐boreal species, accessibility had little importance for species with wide boreal distributions, as expected from their more widespread, northern glacial distributions. In conclusion, even the ranges of many widespread forest plant species are probably still moderately to strongly limited by postglacial migrational lag. Therefore, although species ranges are also strongly influenced by climate, we cannot expect most forest plant species to closely track the expected 21st century climatic changes.  相似文献   

20.
A phylogenetic analysis of mitochondrial DNA (mtDNA) restriction sites was used to examine the geographic history of the Cyprinodon nevadensis complex of pupfishes, a group of four species (seven extant subspp.) in two endorheic (closed) basins of the Death Valley System in California and Nevada (Owens River Valley and Ash Meadows-Death Valley). The mtDNA results suggest that the group contains mtDNAs from two divergent clades. One such clade is represented by the mtDNAs of the Owens Valley pupfish (C. radiosus) and the existing species in the Colorado River (C. macularius), while the other includes the mtDNAs of the Ash Meadows-Death Valley species (C. nevadensis, C. salinus, and C. diabolis) and a species located much farther to the east (C. fontinalis from the Guzman Basin, Chihuahua, Mexico). These results, together with evidence from other studies, suggest two separate invasions of the Death Valley System by pupfishes carrying phylogenetically divergent mtDNAs. The C. nevadensis complex apparently is either an artificial group or else it is monophyletic and its genetic history includes loss of the original mtDNA in either Owens Valley or Ash Meadows-Death Valley following genetic introgression after an invasion by a pupfish carrying a divergent mtDNA.  相似文献   

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