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The flagellation and taxonomy of species of Acetobacter   总被引:6,自引:0,他引:6  
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The taxonomy and distribution of Azolla species in southern Africa   总被引:2,自引:0,他引:2  
The three Azolla species which occur in southern Africa, A. pinnata var. pinnata, A. nilotica and A. filiculoides are identified and their distributions illustrated. The endosymbiotic cyanobacterium Anabaena azollae occurred in dorsal leaf lobe cavities of all three species. The first two species are indigenous to southern Africa, whilst the third, A. filiculoides , is an introduced species from North America. Possible means whereby this species could have been introduced are discussed.  相似文献   

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Identifying the individuals within a population can generate information on life history parameters, generate input data for conservation models, and highlight behavioural traits that may affect management decisions and error or bias within census methods. Individual animals can be discriminated by features of their vocalisations. This vocal individuality can be utilised as an alternative marking technique in situations where the marks are difficult to detect or animals are sensitive to disturbance. Vocal individuality can also be used in cases were the capture and handling of an animal is either logistically or ethically problematic. Many studies have suggested that vocal individuality can be used to count and monitor populations over time; however, few have explicitly tested the method in this role. In this review we discuss methods for extracting individuality information from vocalisations and techniques for using this to count and monitor populations over time. We present case studies in birds where vocal individuality has been applied to conservation and we discuss its role in mammals.  相似文献   

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Behavioral research has long had an important role in the conservation of terns (Ayes: Stemidae). Habitat management and restoration of breeding colony sites depends on knowledge of the cues used to select colony and nest sites. For example, conspecific attraction with playback and decoys is commonly used to bring terns to suitable colony sites and habitat modification is often used to increase the availability of suitable nest sites. Tern colonies are interconnected by dispersal, and a metapopulation approach is needed for effective management. Population dynamics are therefore affected by behaviors that influence the frequency of movement among colony sites: site fidelity, natal and breeding dispersal, and group adherence. The monogamous breeding system of terns should keep effective population size similar to census population size, but variation in sex ratios (likely resulting from sex differences in behavior) and in parental quality can result in a smaller than expected effective population size. In addition to the behavior of terns, knowledge of the behavior of predators on terns contributes to management plans, because predator behavior can sometimes be manipulated and predation is often performed by only a few specialized individuals. Other examples of links between tern behavior and conservation are also briefly reviewed, such as behavioral toxicology research and studies of behavioral responses to human disturbance and manmade structures. More work is needed on the behavior of migratory terns at staging sites, stopover sites and wintering grounds, and on the behavior of less well-studied species and species in less well-studied geographic regions [Current Zoology 60 (4): 500-514, 2014].  相似文献   

7.
Eef Arnolds 《Plant biosystems》2013,147(6):779-795
Abstract

The motives for the conservation of fungi are briefly outlined. The data and methods needed for successful use of fungi in environmental conservation are mentioned. A survey is given of the main habitats of threatened fungi in Western and Central Europe, including data on the significance of their mycoflora, the causes of decrease and possible measures to improve the situation. The value of macrofungi as bio-indicators for environmental quality is discussed and demonstrated with three examples: the indicator value of wood-inhabiting fungi for undisturbed forest sites; of ectomycorrhizal fungi for air pollution stress in forests and of saprotrophic fungi for the duration of undisturbed grassland use. Lists of indicator species with different indicator values for air pollution stress and grassland use are provided.  相似文献   

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We compared forest gardens, or tembawang, in twoareas in West Kalimantan, Indonesia, to patches of primary forest in terms ofsuccessional stage, mode of dispersal and characteristics of human use ofnon-planted tree species. This information was acquired for 144 tree speciesinventoried in six tembawang forest gardens and two intactnatural forest patches, through interviews at the site and a survey of theliterature. In particular older tembawang were found tohave practically the same proportions of species of different successionalstages and modes of dispersal as natural forests, thus emphasising the potentialof tembawang in conserving tree species. Non-planted treespecies of tembawang and natural forests also havepractically indistinguishable spectra of human uses, indicating that themanagement of these tembawang does not significantlydiscriminate between species with certain uses. However, we also identified twoaspects that should be taken into account in considering the conservation roleof tembawang. The floras of the two study areas showedsignificant regional differentiation, implying that efficient conservation inWest Kalimantan needs to have a rather dense network. We also found that latesuccessional species and animal-dispersed species oftembawang were more commonly geographically widespread thanspecies of the same ecological characteristics found in natural forests. Thus,even if tembawang are similar to natural forests in termsof numbers of species with different ecological characteristics, the compositionof non-planted tree species in tembawang is not a randomsample from natural forest, but overrepresents species that are easily dispersedand/or established.  相似文献   

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《Journal of bryology》2013,35(1):45-55
Abstract

The Fissidens flora of Singapore has been investigated and shown to consist of 16 species, including one new species, F. pseudoceylonensis . F. crispulus var. robinsonii is proposed as a new combination and two taxa (F. mittenii var. javensis M.Fleisch. and F. ceylonensis ssp. simplex M.Fleisch.) are reduced to synonyms of F. pellucidus Hornsch. and F. ceylonensis Dozy & Molk. respectively. The biodiversity of Singapore's Fissidens flora is compared with that of Peninsular Malaysia and Pulau Tioman and the ecological and conservation implications are discussed.  相似文献   

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To elucidate the factors underlying species conservation priority setting, we analysed the relationships among species’ structural complexity, scientific attention, threatened species listing, and conservation investments at different organisational levels, including global, European, national, and sub-national. Although the literature often highlights the need to consider criteria other than extinction risk status, our results show that an excessive use of Red lists still persists in the setting of conservation priorities. We found that organismal complexity, available scientific information, and species listing combine together to create a positive feed-back loop, in which more complex organisms have a larger proportion of threatened species in the Red lists and legal lists. This bias promotes research that is devoted to understanding conservation problems as well as more funds invested to solve them. We propose that a sort of pitfall-trap is currently constraining the species conservation priority setting, in which few species, mainly threatened and better-known species, tend to receive most of the funds and policy attention. To counteract this pitfall-trap, we highlight the need to increase scientific effort on lower taxa and expand Red lists to assess lesser-known taxonomic groups as well as the need to use other criteria for species conservation prioritisation.  相似文献   

14.
Taxonomies based on morphological traits alone sometimes provide inadequate or misleading guides to phylogenetic distinctions at the subspecies and species levels. Yet taxonomic assignments inevitably shape perceptions of biotic diversity, including recognition of endangered species. Case histories are discussed in which the data of molecular genetics revealed prior systematic errors of the two possible kinds: taxonomic recognition of groups showing little evolutionary differentiation, and lack of taxonomic recognition of phylogenetically distinct forms. In such cases, conservation efforts for 'endangered species' can be misdirected with respect to the goal of protecting biological diversity.  相似文献   

15.
The statistical rigor of species delimitation has increased dramatically over the past decade. Coalescent theory provides powerful models for population genetic inference, and is now increasingly important in phylogenetics and speciation research. By applying probabilistic models, coalescent-based species delimitation provides clear and objective testing of alternative hypotheses of evolutionary independence. As acquisition of multilocus data becomes increasingly automated, coalescent-based species delimitation will improve the discovery, resolution, consistency, and stability of the taxonomy of species. Along with other tools and data types, coalescent-based species delimitation will play an important role in an integrative taxonomy that emphasizes the identification of species limits and the processes that have promoted lineage diversification.  相似文献   

16.
The role of infectious diseases in biological conservation   总被引:1,自引:0,他引:1  
Recent increases in the magnitude and rate of environmental change, including habitat loss, climate change and overexploitation, have been directly linked to the global loss of biodiversity. Wildlife extinction rates are estimated to be 100–1000 times greater than the historical norm, and up to 50% of higher taxonomic groups are critically endangered. While many types of environmental changes threaten the survival of species all over the planet, infectious disease has rarely been cited as the primary cause of global species extinctions. There is substantial evidence, however, that diseases can greatly impact local species populations by causing temporary or permanent declines in abundance. More importantly, pathogens can interact with other driving factors, such as habitat loss, climate change, overexploitation, invasive species and environmental pollution to contribute to local and global extinctions. Regrettably, our current lack of knowledge about the diversity and abundance of pathogens in natural systems has made it difficult to establish the relative importance of disease as a significant driver of species extinction, and the context when this is most likely to occur. Here, we review the role of infectious diseases in biological conservation. We summarize existing knowledge of disease-induced extinction at global and local scales and review the ecological and evolutionary forces that may facilitate disease-mediated extinction risk. We suggest that while disease alone may currently threaten few species, pathogens may be a significant threat to already-endangered species, especially when disease interacts with other drivers. We identify control strategies that may help reduce the negative effects of disease on wildlife and discuss the most critical challenges and future directions for the study of infectious diseases in the conservation sciences.  相似文献   

17.
The paper focuses on conservation agriculture (CA), defined as minimal soil disturbance (no-till, NT) and permanent soil cover (mulch) combined with rotations, as a more sustainable cultivation system for the future. Cultivation and tillage play an important role in agriculture. The benefits of tillage in agriculture are explored before introducing conservation tillage (CT), a practice that was borne out of the American dust bowl of the 1930s. The paper then describes the benefits of CA, a suggested improvement on CT, where NT, mulch and rotations significantly improve soil properties and other biotic factors. The paper concludes that CA is a more sustainable and environmentally friendly management system for cultivating crops. Case studies from the rice-wheat areas of the Indo-Gangetic Plains of South Asia and the irrigated maize-wheat systems of Northwest Mexico are used to describe how CA practices have been used in these two environments to raise production sustainably and profitably. Benefits in terms of greenhouse gas emissions and their effect on global warming are also discussed. The paper concludes that agriculture in the next decade will have to sustainably produce more food from less land through more efficient use of natural resources and with minimal impact on the environment in order to meet growing population demands. Promoting and adopting CA management systems can help meet this goal.  相似文献   

18.
The taxonomy of Sarcocystis (Protozoa, Apicomplexa) species   总被引:2,自引:0,他引:2  
The taxonomy of the heteroxenous apicomplexan protozoan genus Sarcocystis was reviewed, and a list of 122 species with their synonyms and hosts given. Both definitive and intermediate hosts are known for only 56 species. The fine structure of the sarcocyst wall may change with age and is not considered necessarily satisfactory for separating species. Specificity for the intermediate host is not narrow for all species. Earlier work on transmission of the parasite from one intermediate host to another should be repeated in the light of present knowledge of the life cycle of species of Sarcocystis.  相似文献   

19.
Suggestions that the extinct Vegas Valley leopard frog (Rana fisheri = Lithobates fisheri) may have been synonymous with one of several declining species have complicated recovery planning for imperiled leopard frogs in southwestern United States. To address this concern, we reconstructed the phylogenetic position of R. fisheri from mitochondrial and nuclear sequence data obtained from century-old museum specimens. Analyses incorporating representative North American Rana species placed archival specimens within the clade comprising federally Threatened Chiricahua leopard frogs (Rana chiricahuensis = Lithobates chiricahuensis). Further analysis of Chiricahua leopard frogs recovered two diagnosable lineages. One lineage is composed of R. fisheri specimens and R. chiricahuensis near the Mogollon Rim in central Arizona, while the other encompasses R. chiricahuensis populations to the south and east. These findings ascribe R. chiricahuensis populations from the northwestern most portion of its range to a resurrected R. fisheri, demonstrating how phylogenetic placement of archival specimens can inform recovery and conservation plans, especially those that call for translocation, re-introduction, or population augmentation of imperiled species.  相似文献   

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