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101.
In this paper a spatially implicit neutral model for explaining the edge effects between habitats is proposed. To analyze this model we use two different approaches: a discrete approach that is based on the Master equation for a one step jump process and a continuous approach based on the approximation of the discrete jump process with the Kolmogorov-Fokker-Planck forward and backward equations. The discrete and continuous approaches are applied to analyze the species abundance distributions and the time to species extinction. Moreover, with the aid of the continuous approach a realistic classification of the behavior of species in local communities is developed. The species abundance dynamics at the edge between two distinct habitats is compared with those located in the homogeneous interior habitats using species abundance distributions and the first time to species extinction. We show that the structure of the links between local community and the metacommunity plays an important role on species persistence. Specifically, species at the edge between two distinct metacommunities have higher extinction rate than those in the interior habitats connected only to one metacommunity. Moreover, the same species might be persistent in the homogeneous interior habitat, but its probability of extinction from the edge local community could be very high. 相似文献
102.
Hubbell’s neutral theory claims that ecological patterns such as species abundance distributions can be explained by a stochastic
model based on simple assumptions. One of these assumptions, the point mutation assumption, states that every individual has the same probability to speciate. Etienne et al. have argued that other assumptions on the speciation process could be
more realistic, for example, that every species has the same probability to speciate (Etienne, et al. in Oikos 116:241–258, 2007). They introduced a number of neutral community models with a different speciation process, and conjectured formulas for
their stationary species abundance distribution. Here we study a generalised neutral community model, encompassing these modified
models, and derive its stationary distribution, thus proving the conjectured formulas. 相似文献
103.
Nadja Kabelitz Jirina Machackova Gwenaël Imfeld Maria Brennerova Dietmar H. Pieper Hermann J. Heipieper Howard Junca 《Applied microbiology and biotechnology》2009,82(3):565-577
In order to obtain insights in complexity shifts taking place in natural microbial communities under strong selective pressure,
soils from a former air force base in the Czech Republic, highly contaminated with jet fuel and at different stages of a bioremediation
air sparging treatment, were analyzed. By tracking phospholipid fatty acids and 16S rRNA genes, a detailed monitoring of the
changes in quantities and composition of the microbial communities developed at different stages of the bioventing treatment
progress was performed. Depending on the length of the air sparging treatment that led to a significant reduction in the contamination
level, we observed a clear shift in the soil microbial community being dominated by Pseudomonads under the harsh conditions
of high aromatic contamination to a status of low aromatic concentrations, increased biomass content, and a complex composition
with diverse bacterial taxonomical branches.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
The online version of an erratum to this article can be found at http://dx.doi.org/.
An erratum to this article can be found at 相似文献
104.
Many factors affect the distribution of species richness. This study examines the relative influence of habitat heterogeneity,
climate, human disturbance, and spatial structure on the species-richness distribution of terrestrial vertebrates (amphibians,
reptiles, birds and mammals) in mainland Spain. The results indicate that spatial structure and environment exert similar
influences on species richness. For all four taxa, species richness increases southward and northward, being lower in the
center of the country, when controlled for other variables. This may be the result of a peninsular effect, as found in other
studies, and reflect the importance of historical events on species richness in the Iberian Peninsula. Climate is more important
than habitat heterogeneity in determining species richness. Temperature is positively correlated with amphibian, reptile,
and bird species richness, while mammalian species richness is highest at intermediate temperatures. This effect is stronger
in ectotherms than among endotherms, perhaps reflecting physiological differences. Precipitation positively correlates with
bird and mammalian species richness, but has no effect on ectotherm species richness. Amphibian species richness increases
with altitudinal range, and bird species richness with habitat diversity. Human population density is positively correlated
with bird and mammalian species richness, but does not affect ectotherm species richness, while amphibian and bird species
richness is highest at moderate levels of human land alteration (farmland). However, unexplained variance remains, and we
discuss that the effects of environmental variables on species richness may vary geographically, causing different effects
to be obscured on a national scale, diminishing the explanatory power of environmental variables. 相似文献
105.
Aquatic macrophytes provide essential spawning and nursery habitat for fish, valuable food source for waterfowl, migratory
birds and mammals, and contribute greatly to overall biodiversity of coastal marshes of the Laurentian Great Lakes. Two approaches
have been used to survey the plant community in coastal wetlands, and these include the grid (GR) and transect (TR) methods.
These methods have been used to identify the average species richness at different sites, but their suitability for determining
total species richness of a site has not been tested. In this paper, we compare the performance of these two established methods
with that of the Stratified method (ST), which uses the sampler’s judgment to guide them to different habitat zones within
the wetland. We used the three protocols to compare species richness of six coastal wetlands of the Great Lakes, three pristine
marshes in eastern Georgian Bay (Lake Huron) and three degraded wetlands in Lake Ontario, Canada. The greatest species richness
was associated with the ST method, irrespective of wetland quality. The ST method was also more efficient (fewer quadrats
sampled), and revealed the most number of unique (those found with only one method) and uncommon species (those found in <5%
of the quadrats). Despite these statistical differences, we found that sampling method did not significantly affect the performance
of a recently developed index of wetland quality, the Wetland Macrophyte Index. These results have important implications
for designing macrophyte surveys to track changes in biodiversity and wetland quality. 相似文献
106.
Aung Swe Rajesh Jeewon Stephen B. Pointing Kevin D. Hyde 《Biodiversity and Conservation》2009,18(6):1695-1714
Nematode-trapping fungi are ubiquitous in terrestrial habitats in dung, soils, litter and woody debris and they also occur
in freshwater, but only one species has been found in marine habitats. The purpose of this study was therefore to investigate
whether nematode-trapping fungi occurred in mangrove habitats. To achieve this we assessed the diversity of nematode-trapping
fungi on decaying litter from mangroves, freshwater and terrestrial habitats (22 sites) in Hong Kong. Composite samples (n = 1,320) of decaying litter (wood and leaves) were examined and a total of 31 species of nematode-trapping fungi belonging
to four genera, Arthrobotrys, Monacrosporium, and Dactylella were recorded. Twenty-nine species reported in this study are new records for Hong Kong and 16 species are new records from
mangrove habitats worldwide. Nematode trapping fungi are therefore present in marine environments. Commonly encountered taxa
were Arthrobotrys oligospora and Monacrosporium thaumasium which are abundant in all habitats. A. oligospora, M. thaumasium and Arthrobotrys musiformis were frequent (F > 10%). Twenty-six species were rare (0.16–9.32%). Species richness and diversity was higher in terrestrial than in freshwater
and mangrove habitats (ANOVA, P < 0.001). A higher mean diversity was observed on decaying leaves as compared to decaying wood in all habitats (P < 0.001). Based on Shannon diversity index, it was also observed that taxa characterized by adhesive nets were more frequent
in all habitats. This can be explained by the fact that these taxa may have a better competitive saprotrophic ability which
would allow them to compete favourably in nutrient limited environments. Abiotic factors that could be linked to differences
in species diversity between decaying wood and leaves are also discussed. 相似文献
107.
Adam Felton Joern Fischer David B. Lindenmayer Rebecca Montague-Drake Arianne R. Lowe Debbie Saunders Annika M. Felton Will Steffen Nicola T. Munro Kara Youngentob Jake Gillen Phil Gibbons Judsen E. Bruzgul Ioan Fazey Suzi J. Bond Carole P. Elliott Ben C. T. Macdonald Luciana L. Porfirio Martin Westgate Martin Worthy 《Biodiversity and Conservation》2009,18(8):2243-2253
Recent reviews of the conservation literature indicate that significant biases exist in the published literature regarding
the regions, ecosystems and species that have been examined by researchers. Despite the global threat of climatic change,
similar biases may be occurring within the sub-discipline of climate-change ecology. Here we hope to foster critical thought
and discussion by considering the directions taken by conservation researchers when addressing climate change. To form a quantitative
basis for our perspective, we assessed 248 papers from the climate change literature that considered the conservation management
of biodiversity and ecosystems. We found that roughly half of the studies considered climate change in isolation from other
threatening processes. We also found that the majority of surveyed scientific publications were conducted in the temperate
forests of Europe and North America. Regions such as Latin America that are rich in biodiversity but may have low adaptive
capacity to climate change were not well represented. We caution that such biases in research effort may be distracting our
attention away from vulnerable regions, ecosystems and species. Specifically we suggest that the under-representation of research
from regions low in adaptive capacity and rich in biodiversity requires international collaboration by those experienced in
climate-change research, with researchers from less wealthy nations who are familiar with local issues, ecosystems and species.
Furthermore, we caution that the propensity of ecologists to work in essentially unmodified ecosystems may fundamentally hamper
our ability to make useful recommendations in a world that is experiencing significant global change. 相似文献
108.
Ramón Pérez Gil Salcido Inés Arroyo Quiroz Roberto Romero Ramírez 《Biodiversity and Conservation》2009,18(5):1421-1434
Documenting financial resources in biodiversity conservation is a key aspect worldwide in order to set priorities and use
effectively the limited resources available. In Mexico, a megadiverse country, studies on financial resources invested in
biodiversity conservation are scarce and do not address funding for conservation comprehensively. Using recent data from several
sources and applying criteria based on the national priorities for conservation, we compiled, systematized and analyzed data
at a national scale on financing sources, financial resources and conservation organizations and their projects. The information
obtained is presented in various ways and part of it (case study) is already an information system that can be continuously
up-dated. Some of the results show the following: a steady diversification of mechanisms and methods for raising funds for
conservation; an increase in governmental budgets; the acknowledgment by the private sector of the importance of biodiversity
conservation; a greater technical capacity in people and organizations working in conservation; a greater accessibility of
financial resources to support and maintain conservation projects; yet a short term vision in conservation projects; among
other. Although the results obtained through this study are a first approach, they can now be used as a baseline to continue
gathering and analyzing information on conservation financing in Mexico. 相似文献
109.
110.
With only five protected areas dedicated to the conservation of biodiversity (two national parks, one strict nature reserve
and two faunal reserves), Guinea has one of the smallest protected area networks in West Africa. As a result, two of the five
ecoregions of the country and six of the 14 globally threatened large and medium-sized mammals occurring in Guinea are not
found in the national protected area network. To identify areas with high biodiversity that could be included in the national
protected area network, we used the Key Biodiversity Areas (KBA) methodology. We devised a scoring system to rank the identified
KBAs according to their relative conservation significance. We identified a total of 16 KBAs throughout the country. Their
proclamation as protected areas would result in the protection of all ecoregions and all but one of Guinea’s globally threatened
large and medium-sized mammals. Twelve of the 16 KBAs have the legal status of classified forest, a status that should facilitate
the change into formal biodiversity protected areas (IUCN category I–IV). Our analysis indicates that even if only the two
areas with the highest conservation significance score, the Ziama and Diécké forests, become formal protected areas, this
would provide protection to both the western Guinean lowland forests, one of the most threatened ecoregions in Africa, and
to 11 of the 14 threatened large and medium-sized mammals occurring in Guinea. 相似文献