首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
This is the very first checklist of the terrestrial gastropods of Nepal. It includes 138 species and six subspecies, of which 22 species are endemic and four are introduced. It highlights 34 species recorded for the first time in Nepal and provides new distribution records for another 30 species.  相似文献   

2.
3.
4.
Studies of geographic distribution and physiological adaptations in theBromeliaceae of coastal Chile and Peru provide insights into the ecological patterns of habit selection and speciation. The hyperarid coastal Atacama and Peruvian Deserts along the Pacific coast of South America contain a surprisingly rich flora of bromeliad species. These include representatives of all threeBromeliaceae subfamilies: two terrestrialBromelioideae and two terrestialPitcairnioideae, all with rooted growth morphologies, and 14 species ofTillandsioideae (allTillandsia) with epiphytic and unrooted, terrestraial representatives. TheBromelioideae are represented by two species ofPuya Molina, one each in Peru and Chile. ThePitcairnioideae are represented by two genera,Deuterocohnia andPitcairnia, with one species each. The 14Tillandsia species are distributed in five subgenera which have successfully invaded the coastal deserts, and include both widespread and local endemics with xeromorphic adaptations. All theTillandsia species are epiphytic in the broad sense, but in addition to growing on plants, they are found growing on rocks (i.e. saxicolous or epilithic). Six species (T. purpurea, T. latifolia, T. capillaris, T. marconae, T. werdermanii, andT. landbeckii) have evolved a highly specialized substrate ecology where they grow essentially unrooted on sand (i.e. epiarenic). Nowhere in the world are bromeliads more dominant or have more biomass than in these coastal species growing on sand. Many of these species grow at the absolute limits of vascular plant tolerance, with the entire community consisting of a singleTillandsia species. Rooted, terrestrial bromeliads in the coastal lomas formations (allPitcairnioideae) include CAM, C3, and C3-CAM flexible taxa in their metabolic systems, the CAM species growing in the most arid sites along the coast and C3 species growing in the most mesic habitats within the center of the coastal fog belt where fog moisture input is highest. All of the epiphyticTillandsia species of the coastal desert region utilize CAM metabolism entirely or in part. At least two species,T. latifolia andT. tragophoba, utilize a flexible C3-CAM mode of carbon fixation. Whereas most of the desert-inhabitingTillandsia species have relatively narrow leaves covered by water absorbing trichomes on their surface,T. multiflora in northern Peru andT. tragophoba in northern Chile are tank-forming species where the bases of the leaves form a water-containing reservoir. The occurrence of the latter as a local endemic in hyperarid northern Chile is remarkable since it occurs thousands of kilometers south of its closest potential relatives in the central Andes.  相似文献   

5.
The abundance of terrestrial pteridophytes was studied in eight sites in Western Amazonia, all representing lowland tropical rain forest in non-inundated terrain ( tierra firme ). In each site, a sample plot ranging from 0.25 ha to 1.00 ha in area was inventoried and all terrestrial pteridophytes were recorded. In total, 27,000 individuals representing sixty-four species were encountered, with each plot having between fourteen and thirty-three species. The plots represented a gradient from nutrient-poor sandy soils to relatively fertile clay soils, and it was found that their floristic compositions clearly correlated with the differences in the soils. Two-thirds of the species were restricted either to poor, intermediate or rich soils, while less than a tenth were found growing on all soil types. Analyses of species lists from another twenty neotropical localities supported the result that some pteridophyte species associate, whereas other species are never found growing together. The floristic similarities among sites showed no relationship to the geographical distances between them, but rather reflected similarities in soils. It is concluded that pteridophytes are good indicators of such ecological conditions, and that when interpreting biogeographical patterns in the neotropical rain forests, it is important to take into account the distribution of edaphically different habitats.  相似文献   

6.
Climatic, morphological and cultural factors of the Chilean littoral in terrestrial environment and the geographic and bathimetric distribution of marine littoral species are analyzed, in relation to the oceanographic conditions of the coast. Disagreements between the marine and terrestrial latitudinal zonation are explained by the special littoral morphology and the thermic anomalies produced by the currents and by the coastal upwelling. For the littoral waters, the temperatures of North Chile are markedly colder than accepted in the literature in making biogeographic analysis, due to near isotherms parallel to the coast and because the information considered does not answer the strictly littoral conditions. In relation to bathimetric distribution, the subsuperficial layers show anoxic characteristics for the benthic elements at deepest 50 m in northern Chile (distributive barricade) and extremely low salinities in the patagonic region limiting the species distribution in the superficial layers. Three littoral biogeographic Provinces are defined for the South‐Ost Pacific.  相似文献   

7.
There is an urgent need for comprehensive national databases on alien plant species, especially in developing countries. Despite the fact that plant invasions are considered a major threat to biodiversity, they have been poorly studied or not considered a conservation priority in South America. We aim to assess alien plant distribution in Chile, using the first comprehensive public alien plant database, and discuss the implications of using herbarium records to develop national databases of alien plants. We used herbarium records to assemble a comprehensive national database of alien plants. We calculated the number of alien and native species and specimens recorded in each 10 × 10 km cell. We evaluated sampling efforts and tested for relationships between alien and native species collections, as well as other spatial patterns along the latitudinal gradient. Alien and native species richness was positively correlated. Alien plants were mostly collected in central Chile, with few species collected in both the extreme north and south. However, native plants were strongly collected in central Chile, as well as in both extremes of the country. Alien and native plants followed the same pattern of accumulation along the latitudinal gradient, with native plants being relatively more collected than alien plants. Herbarium records provide valuable baseline information to evaluate plant species distribution. However, there are important gaps in this database, (e.g. variable sampling effort for alien and native plants, incomplete information on life-history traits). Given scientists and land managers increasing demand for baseline information and the high cost of collecting such data in developing countries, herbarium records should be used more frequently for research and management of plant invasions.  相似文献   

8.
安徽祁门地区蕨类植物区系研究   总被引:4,自引:0,他引:4  
安徽祁门地区蕨类植物共有107种(包括变种、变型),隶属于28科56属,其中发现安徽地理分布新记录种1个,即丝带蕨(Drymotaenium miyoshianum)。该区的蕨类植物优势科为鳞毛蕨科(Dryopte ridaceae)、水龙骨科(Polypodiaceae)和蹄盖蕨科(Athyriaceae);优势属为鳞毛蕨属(Dryopteris)、卷柏属(Selaginella)和复叶耳蕨属(Arachniodes)。属的地理成分以泛热带为主,亚热带和温带分布次之;种的地理分布则以中国-日本分布和中国特有分布为主。祁门蕨类植物区系在区系区划上应属于典型的华东地区。该区的蕨类植物生态类型以土生为主。种的相似性分析和属的聚类分析表明:该区系与三清山和天童山的关系密切,而与白石砬子等关系疏远。  相似文献   

9.
10.
The geographical extent of exotic plant species is a major component of invasiveness, which has been explained by intrinsic attributes of the plants, such as growth rate, reproductive type, life form, and biogeographical origin. We assessed quantitatively life cycle and biogeographical origin as determinants of the geographical distribution of naturalized plants in continental Chile, using minimum residence time (MRT) as an estimator of introduction date. We assembled a database with information on 428 plants (principally herbs) in continental Chile, corresponding to 61% of the exotic naturalized flora. For each species we recorded: (1) minimum residence time (introduction date or first recorded date in the country); (2) biogeographical origin (American, Eurasian, others); (3) life cycle (annual, perennial, others); (4) number of Chilean regions occupied by the plant. We found that 82 species (19%) have been recorded in only one region of Chile, while only three species have been found in all 13 regions of the country. About 89% of the species (381) have been found only in central Chile (Regions IV to VIII), while the remaining 11% (47) are found only in the northern (Regions I to III) or southern parts of the country (Regions IX to XII). We detected significant differences in regional spread of naturalized plants according to minimum residence time: those species with shorter MRT had more limited spread ranges than those with longer MRT. Biogeographical origin and life cycle did not explain geographical extent in Chile. This study shows that historical factors are more important than biological ones in determining the geographical extent of naturalized plants in continental Chile. Thus, caution should be exercised when assigning value to biological attributes that may confer invasiveness to naturalized plants.  相似文献   

11.
Easy, economic, precise species authentication is currently necessary in many areas of research and diagnosis in molecular biology applied to conservation studies of endangered species. Here, we present a new method for the identification of three fox species of the Lycalopex genus in Chile. We developed an assay based on high‐resolution melt analysis of the mitochondrial cytochrome B gene, allowing a simple, low cost, fast, and accurate species determination. To validate the assay applicability for noninvasive samples, we collected fecal samples in the Atacama Desert, finding unexpectedly one species outside of its known distribution range. We conclude that the assay has a potential to become a valuable tool for a standardized genetic monitoring of the Lycalopex species in Chile.  相似文献   

12.
13.
The sedge-feeding moth Bactra verutana Zeller, 1875 (Lepidoptera: Tortricidae: Olethreutinae: Bactrini), described from Dallas, Texas, USA, is widespread, recorded throughout much North America, Central and South America, including the Caribbean, and Africa. The species is recorded for the first time from Chile based on specimens collected in the coastal valleys of the Atacama Desert, where its larvae feed on Cyperus corymbosus Rottb. var. subnodosus (Nees & Meyen) Kük. (Cyperaceae). A single DNA barcode haplotype, which is widespread in USA, was found in two Chilean specimens sequenced.  相似文献   

14.
In this paper, the very first checklist of the freshwater leeches of Maloe More Strait, a special part of Lake Baikal, is presented. It includes 14 free-living and parasitic species, of which four species belong to endemic Baikal genera – two species from Baicalobdella and one species each from Baicaloclepsis and Codonobdella. The checklist highlights six potentially new morphological species recorded for the first time in the area. The exact systematic position is stated for all leech species. Each species from the list is provided with information on taxonomic synonymy, data on its geographic distribution, and ecological characteristics. New species records are additionally provided with brief morphological characteristics and photos of their external morphology.  相似文献   

15.
Belmonte  G.  Potenza  D. 《Hydrobiologia》2001,(1):171-176
In the Ponto-Mediterranean Province, the geographical distribution of 19 species plus 1 variety belonging to the family Acartiidae has been studied. The study utilised cartographic techniques of terrestrial biogeography and the entire Province was subdivided in 1375 squares. The geographic distributions obtained derived from data published during the last 126 years. The first result was that about 3/4 of the area considered has never been sampled, and only about 8% of the entire area has been repeatedly sampled (at least seasonally). Long time-series of sampling are known only from very few sites. The species considered belong to three genera. Species distributions are discontinuous either in space or in time. Three species are endemic. The historical analysis suggests that four species arrived in the Province recently (two of them are Lessepsian migrants; the others have been introduced by human activities). Two species appear to have crossed the Suez Canal from the Mediterranean to the Red Sea (anti-Lessepsian migration). Two species are considered to be ante-Lessepsian (they were tropical species present in the Mediterranean before the Suez Canal opening). The doubtful presence of two species in the Mediterranean is discussed. At the present time, it seems that the distribution of many species is rapidly changing, probably as a consequence of the anthropogenic influence on communication between areas of the Province, and supported by the ability of Acartiidae to cross geographic barriers, mainly as resting stages.  相似文献   

16.
The Atacama Desert of northern Chile is considered one of the most arid and extreme environment on Earth. Its core region was described as featuring “Mars-like” soils that were at one point deemed too extreme for life to exist. However, recent investigations confirmed the presence of diverse culturable actinobacteria. In the current review, we discuss a total of 46 natural products isolated to date representing diverse chemical classes characterized from different actinobacteria isolated from various locations in the Atacama Desert. Their reported biological activities are also discussed.  相似文献   

17.
We implicate ecological processes in assembly patterns of Egyptian desert rodents using spatial variation of distribution and composition of local assemblages. We also compare our assemblages to prior analyses of North American and Australian small mammal communities in terms of species richness and representation of trophic groups.We studied patterns of occurrence of 29 rodent species among 335 collecting events in 308 sites using museum specimen records resulting from a country-wide survey. The studied taxa vary greatly in their natural histories and ecology. Fully 69% of studied species (20) were localized in 30 or fewer sites (9% of all sites). Site incidence was closely correlated with the geographic range size of species, while local abundance of a species showed little relationship to its geographic range. The species richness of local assemblages ranged from a lone species at 73 sites to 11 species at 3 sites. A total of 214 different combinations were recorded of which 164 (77%) were unique to a single site. G. gerbillus was both the most abundant and most ubiquitous species. Coexistence with other species was positively correlated with incidence and geographic range size. Body mass distribution was remarkably uniform for the fauna as a whole, and influenced the geographic distributions and abundance of individual species.Our sites have low species richness and substantial variability in species composition, which also characterize desert rodent communities elsewhere. Habitat requirements, exclusive distributions of sibling species, low primary productivity, and Egypt's location all influenced species assembly. The Egyptian and Australian deserts supported higher proportions of low richness assemblages compared to North America. As in North America, Egyptian sites were dominated by granivorous species.  相似文献   

18.
Nucleotide sequence data from the mitochondrial cytochrome b gene were used to evaluate the phylogenetic relationships among mouse opossum species of the genus Thylamys. Based on approximately 1000 bp in five of the six species of the genus and including different localities for some of the species, we concluded that T. macrura from the subtropical forests of eastern Paraguay is the most primitive taxon. Subsequent radiation of the genus is explained mainly via founder effect speciation. This evolutionary scenario would account for the speciation of T. pusilla, T. venusta, T. pallidior, and T. elegans in the Chaco, southern Bolivia and northern Argentina, the Andean Altiplano, the Coastal Desert of Chile, and coastal Perú, respectively. Calibration of a molecular clock set the Pleistocene as the period for the differentiation of Thylamys species. The molecular results confirm the strong genetic connection between populations that inhabit the "pre-cordillera" of northern Chile (T. pallidior) and the canyons that run through the Atacama Desert to the lowlands in northern Chile. Our results confirm the occurrence of two Thylamys species in Chile, T. pallidior and T. elegans, within and south to the Atacama Desert, respectively.  相似文献   

19.
Aim To identify the bioclimatic niche of the endangered Andean cat (Leopardus jacobita), one of the rarest and least known felids in the world, by developing a species distribution model. Location South America, High Andes and Patagonian steppe. Peru, Bolivia, Chile, Argentina. Methods We used 108 Andean cat records to build the models, and 27 to test them, applying the Maxent algorithm to sets of uncorrelated bioclimatic variables from global databases, including elevation. We based our biogeographical interpretations on the examination of the predicted geographic range, the modelled response curves and latitudinal variations in climatic variables associated with the locality data. Results Simple bioclimatic models for Andean cats were highly predictive with only 3–4 explanatory variables. The climatic niche of the species was defined by extreme diurnal variations in temperature, cold minimum and moderate maximum temperatures, and aridity, characteristic not only of the Andean highlands but also of the Patagonian steppe. Argentina had the highest representation of suitable climates, and Chile the lowest. The most favourable conditions were centrally located and spanned across international boundaries. Discontinuities in suitable climatic conditions coincided with three biogeographical barriers associated with climatic or topographic transitions. Main conclusions Simple bioclimatic models can produce useful predictions of suitable climatic conditions for rare species, including major biogeographical constraints. In our study case, these constraints are also known to affect the distribution of other Andean species and the genetic structure of Andean cat populations. We recommend surveys of areas with suitable climates and no Andean cat records, including the corridor connecting two core populations. The inclusion of landscape variables at finer scales, crucially the distribution of Andean cat prey, would contribute to refine our predictions for conservation applications.  相似文献   

20.
Aim To quantify the vulnerability of habitats to invasion by alien plants having accounted for the effects of propagule pressure, time and sampling effort. Location New Zealand. Methods We used spatial, temporal and habitat information taken from 9297 herbarium records of 301 alien plant species to examine the vulnerability of 11 terrestrial habitats to plant invasions. A null model that randomized species records across habitats was used to account for variation in sampling effort and to derive a relative measure of invasion based either on all records for a species or only its first record. The relative level of invasion was related to the average distance of each habitat from the nearest conurbation, which was used as a proxy for propagule pressure. The habitat in which a species was first recorded was compared to the habitats encountered for all records of that species to determine whether the initial habitat could predict subsequent habitat occupancy. Results Variation in sampling effort in space and time significantly masked the underlying vulnerability of habitats to plant invasions. Distance from the nearest conurbation had little effect on the relative level of invasion in each habitat, but the number of first records of each species significantly declined with increasing distance. While Urban, Streamside and Coastal habitats were over‐represented as sites of initial invasion, there was no evidence of major invasion hotspots from which alien plants might subsequently spread. Rather, the data suggest that certain habitats (especially Roadsides) readily accumulate alien plants from other habitats. Main conclusions Herbarium records combined with a suitable null model provide a powerful tool for assessing the relative vulnerability of habitats to plant invasion. The first records of alien plants tend to be found near conurbations, but this pattern disappears with subsequent spread. Regardless of the habitat where a species was first recorded, ultimately most alien plants spread to Roadside and Sparse habitats. This information suggests that such habitats may be useful targets for weed surveillance and monitoring.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号