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排序方式: 共有107条查询结果,搜索用时 31 毫秒
1.
Using Vascular Plants as a Surrogate Taxon to Maximize Fungal Species Richness in Reserve Design 总被引:4,自引:1,他引:3
ALESSANDRO CHIARUCCI† FRANCESCA D'AURIA† VINCENZO DE DOMINICIS† ANGELA LAGANÀ† CLAUDIA PERINI† ELENA SALERNI† 《Conservation biology》2005,19(5):1644-1652
Abstract: Fungi are a hyperdiverse taxonomic group that may be disappearing at a very high rate. Identifying fungal species is difficult in the field, and the use of highly specialized taxonomists is required. Data and expertise on vascular plants are, on the other hand, much more common and easy to find. We tested the potential of using vascular plants as surrogates to select reserve sites that maximize the pooled number of fungal species. We used data from 25 forest plots in Tuscany, Italy, that were sampled for woody plants, all other plants, and fungi. Species richness of woody plants and all other plants did not correlate with species richness of fungi. The gradients in species composition were similar among the three considered groups, as indicated by a detrended correspondence analysis ordination and species complementarity between pairs of plots. Fungal communities of the 25 plots had a lower β diversity than plant communities, and there were no pairs of totally complementary sites. Site prioritization for conservation was obtained through integer linear programming to find for any given number of sites those combinations containing the maximum pooled species richness of woody plants or all plants. The combinations of sites obtained by optimizing vascular plant species did not maximize the pooled species richness of fungi, whereas those obtained by maximizing woody plant species provided better results for sets of four to eight plots, but not for all the possible combinations. These results indicated that, in general, vascular plants cannot be used to maximize fungal species richness. 相似文献
2.
Larval development in the Antarctic nemertean Parborlasia corrugatus (Heteronemertea: Lineidae) 总被引:4,自引:0,他引:4
L. S. Peck 《Marine Biology》1993,116(2):301-310
Embryonic and larval development were followed from fertilisation to settlement in the Antarctic heteronemertean Parborlasia corrugatus (McIntosh, 1876). The first cleavage occurred 10 to 15 h after fertilisation, and the second at 17 h. Larvae hatched at the gastrula stage, between 170 and 200 h post-fertilisation, and were 150 m in diameter. Early larval stages aggregated in dense groups near the surface of incubation vessels and were positively phototactic. Early pilidium larvae were recognisable 435 h post-fertilisation. They were 155×152 m in size, and possessed a complete apical tuft of cilia and a full marginal band of locomotory cilia. At this stage, the gust was visible through the body wall, and the mouth was open and was 40 m in diameter. Late pilidia, 222×193 m in size, were helmet-shaped. They had an apical tuft over 100 m long, and possessed a lobed marginal band of locomotory cilia. Pilidia were observed aggregating close to the bottom of incubation vessels 1200 to 1350 h (50 to 56 d) after fertilisation, and this was interpreted as settlement behaviour. At this stage, the apical tuft had been lost and they were highly contractile, being capable of compressing their bodies. However, neither developing juveniles within the larval envelope nor hatched juveniles were observed. Pilidia consumed the microalgae Tetraselmis suecica, Thalassiosira pseudonana and Isochrysis galbana. They also fed on particulate organic material < 1 m in size, as shown by the presence of material in the guts of larvae offered filtered extracts of algal cultures. There was some indication that larvae could use dissolved organic material, since pilidia held in seawater with organic material removed did not survive as long as those in filtered seawater or in filtered water with added amino acids. However, the only larvae to exhibit settlement behaviour in the feeding experiments were those offered Tetraselmis succica and Thalassiosira pseudonana, and these required a longer development time to reach this stage than pilidia in the standard cultures, where a mixed algal diet was offered. 相似文献
3.
Eugene L. Peck 《Journal of the American Water Resources Association》1997,33(1):125-134
ABSTRACT: Many users of hydrometeorological records are not aware of the number of inconsistencies and biases that occur in hydrometeorological records. Examples are presented illustrating how the exposures of sites for measurement of precipitation, wind, snow on the ground, and evaporation determine to a large extent how useful the records are for estimating areal conditions. For areas where precipitation in the form of snow produces a significant portion of the runoff, a smaller number of quality records may be more valuable for modeling than a much larger number of records of lower quality. Information is presented to show that the overall value of an operational hydrometeorological network is dependent upon how consistent and representative of average conditions the collected records are, especially for mountainous areas in cold regions. 相似文献
4.
Environmental Auditing and the Role of the Accountancy Profession: A Literature Review 总被引:3,自引:0,他引:3
This review of the literature on environmental auditing and the potential role of accountants distinguishes between compliance audits and audits of the environmental management system. After an extensive introduction to the concept, this review focuses on the similarities and differences between an environmental audit and a financial statement audit. The general approach to both types of audits is similar, except that environmental audits are largely unregulated. Both audits place an emphasis on the evaluation of control systems, which is an argument in favor of external auditors playing a role in environmental audits. Another argument for including external accountants is their code of ethics. However, these professionals seem to be reluctant to enter the field of environmental auditing. It is argued that this reluctance is because of a lack of generally accepted principles for conducting environmental audits. If external accountants are engaged in environmental auditing, they should be part of multidisciplinary teams that also include scientists and engineers to avoid a too strong focus on procedures. Rather than treating these audits as totally different, it is proposed that there be a move towards integrated, or even universal, audits. 相似文献
5.
NÁRGILA G. MOURA ALEXANDER C. LEES ALEXANDRE ALEIXO JOS BARLOW SIDNEI M. DANTAS JOICE FERREIRA MARIA DE FÁTIMA C. LIMA TOBY A. GARDNER 《Conservation biology》2014,28(5):1271-1281
Local, regional, and global extinctions caused by habitat loss, degradation, and fragmentation have been widely reported for the tropics. The patterns and drivers of this loss of species are now increasingly well known in Amazonia, but there remains a significant gap in understanding of long‐term trends in species persistence and extinction in anthropogenic landscapes. Such a historical perspective is critical for understanding the status and trends of extant biodiversity as well as for identifying priorities to halt further losses. Using extensive historical data sets of specimen records and results of contemporary surveys, we searched for evidence of local extinctions of a terra firma rainforest avifauna over 200 years in a 2500 km2 eastern Amazonian region around the Brazilian city of Belém. This region has the longest history of ornithological fieldwork in the entire Amazon basin and lies in the highly threatened Belém Centre of Endemism. We also compared our historically inferred extinction events with extensive data on species occurrences in a sample of catchments in a nearby municipality (Paragominas) that encompass a gradient of past forest loss. We found evidence for the possible extinction of 47 species (14% of the regional species pool) that were unreported from 1980 to 2013 (80% last recorded between 1900 and 1980). Seventeen species appear on the International Union for Conservation of Nature Red List, and many of these are large‐bodied. The species lost from the region immediately around Belém are similar to those which are currently restricted to well‐forested catchments in Paragominas. Although we anticipate the future rediscovery or recolonization of some species inferred to be extinct by our calculations, we also expect that there are likely to be additional local extinctions, not reported here, given the ongoing loss and degradation of remaining areas of native vegetation across eastern Amazonia. Doscientos Años de Extinciones Locales de Aves en la Amazonia Oriental 相似文献
6.
7.
The extent to which genetic divergence can occur in the absence of physical barriers to gene flow is currently one of the
most controversial topics in evolutionary biology, with implications for our understanding of speciation, phenotypic plasticity
and adaptive potential. This is illustrated by a recent study reporting a surprising pattern of genetic differentiation between
intertidal and subtidal morphotypes of the broadcast-spawning Antarctic limpet Nacella concinna. To explore this further, we collected almost 400 Antarctic limpets from four depths (intertidal, 6, 15 and 25 m) at Adelaide
island, Antarctica, and conducted a combined morphometric and genetic analysis using 168 polymorphic amplified fragment length
polymorphism (AFLP) loci. Morphological analysis revealed not only pronounced differences between the two morphotypes, but
also a continuous cline in shell shape from the intertidal zone down to 25 m depth, suggesting that the distinction between
the morphotypes may be artificial. Moreover, genetic analysis using both F
st and a Bayesian analogue found no evidence for differentiation either between the two morphotypes or by depth, and a Bayesian
cluster analysis did not detect any cryptic genetic structure. Our findings lend support to the notion that limpets can be
phenotypically highly plastic, although further studies are required to determine unequivocally whether there is any genetic
basis to the observed variation in shell morphology. 相似文献
8.
Myron A. Peck Paul E. Fell Elizabeth A. Allen Jennifer A. Gieg Carl R. Guthke Michael D. Newkirk 《Environmental management》1994,18(2):283-293
Macroinvertebrates were examined on an impounded valley marsh in Stonington, Connecticut, that has changed from aTypha-dominated system to one with typical salt-marsh vegetation during 13 years following the reintroduction of tidal exchange.
Animal populations on this restored impounded marsh were evaluated by comparing them with populations on a nearby unimpounded
valley marsh of roughly the same size. Populations of the high marsh snail,Melampus bidentatus Say, were quantitatively sampled along transects that extended from the water-marsh edge to the upland; those of the ribbed
mussel,Geukensia demissa Dillwyn, were sampled in low marsh areas on transects along the banks of creeks and mosquito ditches. The occurrence of other
marsh invertebrates also was documented, but their abundance was not measured. The mean density ofMelampus was 332±39.6 SE/m2 on the restored impounded marsh and 712±56.0 SE/m2 on the unimpounded marsh. However, since snails were larger on the restored impounded marsh, the difference in snail biomass
was less pronounced than the difference in snail density. MeanMelampus biomass was 4.96±0.52 SE g dry wt/m2 on the restored impounded marsh and 6.96±0.52 SE g dry wt/m2 on the unimpounded marsh. On the two marshes, snail density and biomass varied in relation to plant cover and other factors.
The density and biomass ofGeukensia at the edge of the marsh were comparable on the restored impounded and unimpounded marshes. Mean mussel densities ranged
from 80 to 240/m2 and mean mussel biomass varied from 24.8–64.8 g dry wt/m2 in different low marsh areas. In contrast, below the impoundment dike, meanGeukensia density was 1100±96.4 SE/m2 and meanGeukensia biomass was 303.6±33.28 SE g dry wt/m2. A consideration of all available evidence leads to the conclusion that the impounded marsh is in an advanced phase of restoration. 相似文献
9.
Graduated Driver Licensing (GDL) inserts between the leaner permit and full licensure an intermediate or "provisional" license that allows novices to drive unsupervised but subject to provisions intended to reduce the risks that accompany entry into highway traffic. Introduction of GDL has been followed by lowered accident rates, resulting from both limiting exposure of novices to unsafe situations and by helping them to deal with them more safely. Sources of safer driving include extended learning, early intervention, contingent advancement, and multistage instruction. To extend the learning process, most GDL systems lengthen the duration of the learner phase and require a specified level of adult-supervised driving. Results indicate that extended learning can reduce accidents substantially if well structured and highly controlled. Early intervention with novice traffic violators have shown both a general deterrent effect upon novice violators facing suspension and a specific effect upon those who have experienced it. Making advancement to full licensure contingent upon a violation-free record when driving on the provisional license has also evidenced a reduction in accidents and violations during that phase of licensure. Multistage instruction attempts development of advanced skills only after novices have had a chance to master more basic skills. Although this element of GDL has yet to be evaluated, research indicates crash reduction is possible in situations where it does not increase exposure to risk. While the various elements of GDL have demonstrated potential benefit in enhancing the safety of novice drivers, considerable improvement in the nature and enforcement of GDL requirements is needed to realize that potential. 相似文献
10.
OMAR DOMÍNGUEZ-DOMÍNGUEZ‡ LUIS BOTO† FERNANDO ALDA† GERARDO PÉREZ-PONCE DE LEÓN§ IGNACIO DOADRIO† 《Conservation biology》2007,21(1):168-180
Abstract: The Mesa Central of Mexico is of special conservation interest due to its high richness of freshwater fish species, of which the goodeines are one of the most representative groups. Through an integrated approach, we determined conservation priorities for goodeine populations. We based our recommendations on the genetic diversity (variation in five microsatellite DNA loci) in 10 populations of Zoogoneticus quitzeoensis and on an analysis of ecological (e.g., presence of exotic species), social (e.g., political situation), and environmental (e.g., pollution) information for 52 historical occurrence points for species in the genus Zoogoneticus . Patterns of genetic erosion and genetic diversity indices were closely associated with human impact. Recent bottleneck events were most evident in the populations from remnants of the lakes drained at the beginning of the twentieth century. We identified seven operational conservation units (OCUs), all of which should be conserved because they contain unique portions of the total variation of the species. Special attention needs to be given to increase genetic variability, recover population sizes, and reestablish contact among populations within OCUs. It is imperative to create an integrative and effective approach for the recovery and conservation of the freshwater fish diversity of Central Mexico that is based on social and natural sciences. 相似文献