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1.
Elevational gradients in species richness and endemism of selected plant groups in the central Bolivian Andes 总被引:13,自引:0,他引:13
I analyzed the distribution of Acanthaceae, Araceae, Bromeliaceae, Cactaceae, Melastomataceae, and Pteridophyta in 62 vegetation plots of 400 m2 along an elevational transect between 500 m and 2450 m, and at a nearby lowland site in western Santa Cruz department, Bolivia. These groups were selected because they are physiognomically distinctive, have high species numbers, are comparatively easy to identify, adequately reflect overall floristic relationships, include a wide range of life forms, and are small. The transect was located in the Tucumano-Boliviano biogeographic zone and included drought-deciduous (<850–1000 m), mixed evergreen (850–1000 m to 1800 m), and evergreen Podocarpus-dominated (>1800 m) forests. Elevational patterns of species richness were group-specific and probably related to the ecophysiological properties of each group. Species richness in Pteridophyta and Melastomataceae was correlated with moss cover (i.e., humidity), with elevation (i.e., temperatures) in Acanthaceae and epiphytic Bromeliaceae, with potential evapotranspiration (i.e., ecosystem productivity) in Araceae, and with light availability at ground level in terrestrial Bromeliaceae and Cactaceae. Community endemism generally increased with elevation, but showed a maximum at 1700 m for terrestrial Pteridophyta, and a nonsignificant decline for epiphytic Bromeliaceae and Cactaceae. Endemism was higher for terrestrial than for epiphytic taxa, and was lower among Pteridophyta compared to all other groups, reflecting different dispersal ability among taxonomic and ecological groups. Elevational zonation, tested against a null-model of random distribution of elevational limits, revealed a significant accumulation of upper and lower elevational range boundaries at 900–1050 m and at 1500–1850 m, corresponding to the elevational limits of the main physiognomic vegetation types. 相似文献
2.
Liparis indiraii spec. nova from India is close toL. alata
A. Rich. andL. atropurpurea
Lindl. 相似文献
3.
Isolda Luna Vega Othón Alcántara Ayala Raúl Contreras-Medina 《Biodiversity and Conservation》2004,13(14):2723-2739
The Ternstroemiaceae is a family of vascular plants with many taxonomic problems, basically in the delimitation of some of its species. Little is known about its world distribution and about the real state of conservation of its species. An analysis of the distribution patterns of the Mexican species was undertaken to provide information about the present status of species and possible conservation areas. Also, an analysis of the species richness, endemism centres, extension and location of the areas occupied by these species with a 1:50000 chart index was made. Finally, we propose some of the species of this family to be included in the IUCN Red List of Threatened Species and in the next Mexican Norma Oficial Mexicana 059. 相似文献
4.
It has been claimed that microbial taxa will not exhibit endemism because their enormous populations remove dispersal as an
effective constraint on geographical range. Here we review evidence that challenges this ubiquity hypothesis for the most
speciose group of microbial eukaryotes, the diatoms. Detailed taxonomic inventories using fine-grained morphological characteristics,
molecular markers, and crossing experiments have revealed that the geographic distribution of diatoms ranges from global to
narrow endemic. Records of human-mediated introductions of exotic species further provide a strong indication that geographic
dispersal was limiting in the past. Finally, recent studies have revealed that diatom community structure and diversity are
influenced by geographical factors independent of environmental conditions. Diatom communities are thus regulated by the same
processes that operate in macro-organisms, although possibly to a different degree, implying that dispersal limitation is
significant and the endemism observed in isolated areas is real. These results underscore the pressing need to (1) continue
research into diatom biology, ecology and the factors driving diatom species diversity and geographic distributions, and (2)
protect relatively isolated areas against further introductions of exotic species.
Special Issue: Protist diversity and geographic distribution. Guest editor: W. Foissner. 相似文献
5.
A meaningful effort for the preservation of endemism would require a deep understanding of its related mechanisms and an accurate estimation of its spatial distribution. Here, we applied methods dedicated to species distribution modelling (SDM) to map an integrated index in India's Western Ghats biodiversity hotspot, the endemic tree richness, and to use it for recommendations of protected areas. We then rigorously compared SDM results with spatially explicit and multiscale comparison tools, among them the cutting-edge correlation map and profile (CMP) technique, to finally draw up an endemic richness map with improved accuracy.The endemic richness showed a sharply increasing southward gradient in the Western Ghats, mainly driven by the seasonality of the temperature and the precipitation's stability. This precise quantification of the tree endemism pattern in peninsular India helped in identifying vulnerable areas in terms of conservation of biodiversity as a whole. The Indian authorities recently used our recommendations to extend protected areas in the southern tip of the Indian peninsula to conserve this endemic richness. We believe that spatial analyses and multiscale comparison tools such as those presented here can help conservationists everywhere to better cope with the difficulties met in identifying zones for protected status. 相似文献
6.
7.
V. V. Sivarajan 《Plant Systematics and Evolution》1985,150(3-4):201-204
Thottea ponmudiana sp. nova from Kerala (India) can readily be distinguished from its closest allyTh. siliquosa and all the other known species of the genus by its yellow flowers with purple eyes, deeply lobed perianth with strongly reflexed margins, uniseriate stamens united in three bundles and strongly 4-angled, green, glabrescent fruits. 相似文献
8.
Phyllodiaptomus sasikumari, a new species of calanoid copepod is described from the material collected in several ephemeral ponds and pools in the Palghat
District of Kerala State, South India. 相似文献
9.
Carsten Hobohm 《Biodiversity and Conservation》2003,12(2):279-287
On the basis of 121 areas worldwide, the regressions of plantspecies–area relationships and of endemism–area relationships inlog–log space are calculated. These formulae form the basis forcalculating -values. -Valuesdetermine the ranking of biodiversity hotspots. In most cases, areas which havebeen published as biodiversity hotspots are characterized by high values of, i.e. by rich compositions of vascularplant species and high rates of endemism. 相似文献
10.
Pothos crassipedunculatus
Sivadasan & Mohanan (Araceae), a new species closely related to the SW. Indian endemic and little known speciesP. thomsonianus
Schott is described. It is characterized by the the non-ligulate, shortly vaginate petiole, thickly peduncled inflorescence, broadly ovate spathe and a sessile spadix. It is included in ser.Brevivaginati
Engler of sect.Allopothos
Schott. 相似文献
11.
An analysis of the distribution patterns of 124 Mexican gymnosperm species was undertaken, in order to detect the Mexican
areas with high species richness and endemism, and with this information to propose areas for conservation. Our study includes
an analysis of species richness, endemism and distributional patterns of Mexican species of gymnosperms based on three different
area units (states, biogeographic provinces and grid-cells of 1° × 1° latitude/longitude). The richest areas in species and
endemism do not coincide; in this way, the Sierra Madre Oriental province, the state of Veracruz and a grid-cell located in
the state of Oaxaca were the areas with the highest number of species, whereas the Golfo de México province, the state of
Chiapas and a grid-cell located in this state were the richest areas in endemic species. A weighted endemism and corrected
weighted endemism indices were calculated, and those grid-cells with high values in both indices and with high species richness
were considered as hotspots; these grid-cells are mainly located in Southern and Central Mexico. 相似文献
12.
Ten species of Lepadella Bory de St. Vincent, 1826, including one new species and one new form, are documented from North-Eastern India. Two of these species are new records from this country and six are new reports from N.E. region. Comments are also made on the status and distribution of various Indian taxa. 相似文献
13.
B. K. Sharma 《Hydrobiologia》1990,199(1):29-33
Nine species and subspecies of the genus Testudinella are reported from North-Eastern India. Of these, six are new to India and eight to the North-Eastern region. Remarks are made on their distribution. 相似文献
14.
Panayiotis Trigas Gregoris Iatrou Giorgos Karetsos 《Biodiversity and Conservation》2007,16(2):357-376
The family Caryophyllaceae includes world-wide 86 genera and approximately 2100 species. Greece is one of its most important
centres of diversity and endemism. A total of 428 Caryophyllaceae taxa are distributed in Greece, 161 of them being endemic
to the Greek political territory. The endemic element represents approximately 5% of the global diversity of the family at
the species level. The aim of this paper is to discuss the distribution patterns of the Greek endemic Caryophyllaceae, as
well as those with a limited distribution range to the neighbouring areas of the Balkans and Anatolia, on the basis of the
phytogeographical regions of Greece in order to identify the important regions for their conservation. The majority of the
Greek endemic Caryophyllaceae (64.6%) are distributed in only one single phytogeographical region, or even a smaller area
indicating the extremely restricted distribution ranges of the endemic plants in Greece. Actually 83 Greek endemic Caryophyllaceae
can be grouped on cytotaxonomic criteria. Most of them belong to the category of schizoendemics (91.6%), indicating that the
endemism of Caryophyllaceae in Greece has mainly originated in an active way. Cluster analysis has been used to classify the
phytogeographical regions according to their floristic similarities. Two iterative complementarity methods were used to evaluate
the importance of each phytogeographical region in the conservation of the endemic Caryophyllaceae in Greece. Peloponnisos,
Kriti-Karpathos and Sterea Ellas are the most important phytogeographical regions in this respect, followed by North Central
and North East. When adding the Balkan-Aegean-Anatolian endemics to the analysis, Peloponnisos, North Central, Kriti-Karpathos,
North East and Eastern Aegean result as the most important areas. In every case, an elevated number of sites are required
for the conservation of Caryophyllaceae in Greece, reflecting the great dissimilarities in the floristic composition of the
various phytogeographical regions. The results provided by the different methods are compared. A catalogue of the Greek endemic
Caryophyllaceae is appended. 相似文献
15.
The genera Staurstrum Meyen and Staurodesmus Teil. (Desmidiacea) in Karnataka and Goa States (India)
We report 63 species of Staurastrum Meyen and one of Staurodesmus Teil. from 52 water bodies of Karnataka State and Goa region (1976–77). They include 9 new taxa. The majority are new to S. India. 相似文献
16.
Kelly CM Barker NP Villet MH Broadley DG Branch WR 《Molecular phylogenetics and evolution》2008,47(3):1045-1060
This study constitutes the first evolutionary investigation of the snake family Psammophiidae--the most widespread, most clearly defined, yet perhaps the taxonomically most problematic of Africa's family-level snake lineages. Little is known of psammophiid evolutionary relationships, and the type genus Psammophis is one of the largest and taxonomically most complex of the African snake genera. Our aims were to reconstruct psammophiid phylogenetic relationships and to improve characterisation of species boundaries in problematic Psammophis species complexes. We used approximately 2500 bases of DNA sequence from the mitochondrial and nuclear genomes, and 114 terminals covering all psammophiid genera and incorporating approximately 75% of recognised species and subspecies. Phylogenetic reconstructions were conducted primarily in a Bayesian framework and we used the Wiens/Penkrot protocol to aid species delimitation. Rhamphiophis is diphyletic, with Rhamphiophis acutus emerging sister to Psammophylax. Consequently we transfer the three subspecies of Rhamphiophis acutus to the genus Psammophylax. The monotypic genus Dipsina is sister to Psammophis. The two species of Dromophis occupy divergent positions deeply nested within Psammophis, and we therefore relegate Dromophis to the synonymy of Psammophis. Our results allow division of the taxonomically problematic Psammophis 'sibilans' species complex into two monophyletic entities, provisionally named the 'phillipsii' and 'subtaeniatus' complexes. Within these two clades we found support for the status of many existing species, but not for a distinction between P.p. phillipsii and P. mossambicus. Additionally, P. cf. phillipsii occidentalis deserves species status as the sister taxon of P. brevirostris. 相似文献
17.
M. Sivadasan 《Plant Systematics and Evolution》1986,153(3-4):165-170
Amorphophallus nicolsonianus species nova, with cylindrical or napiform corms, is the only representative of the sect.Rapyogkos in India. All the other hitherto known species of this region have globose or depressed globose corms. The new species is related to some Indochinese species and toA. hildebrandtii (
Engl.)Engl. & Gehrm. from Madagascar. 相似文献
18.
19.
20.
A list is provided of all 358 taxa ofErythroxylum described from the Neotropics through the year 2000, including type specimen citations, probable synonymy, geographic distribution,
and designation of 41 new lectotypes and one new neotype. The list includes 187 accepted species, eight accepted varieties,
27 infraspecific names of uncertain status, and 136 synonyms. A searchable specimen database and type image archive may be
accessed at www.fieldmuseum.org/research_collections/database.htm.
T. Plowman, deceased 7 January 1989. 相似文献