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Biodiversity research combines two dimensions, the horizontalone that contains species diversity, patterns among this diversityand its interconnections and the vertical one that deals withthe history of biodiversity, i.e., its phylogeny. With thesetight interconnections, the importance of so-called "lesserknown groups" such as Nematomorpha and Gastrotricha can be shown.Two examples are the life cycle of Nematomorpha and the phylogeneticposition of Gastrotricha. The life cycle of Nematomorpha isonly partially known and almost no conclusions can be made aboutthe impact of Nematomorpha on their hosts. For the phylogeneticposition of Gastrotricha, alternative hypotheses are available,mainly due to different results of morphological and molecular(18S rDNA) analyses. It is demonstrated how these differenthypotheses influence character interpretation and reconstructionamong Protostomia (Gastroneuralia).  相似文献   

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A new species of freshwater kamptozoan (Entoprocta) is described from the Mae Klong and Prachin Buri Rivers in central Thailand. This brings to two the number of known entoproct species occurring in fresh water. The new species, Loxosomatoides sirindhornae, grows as stolonate colonies; each diminutive zooid has a muscular, unsegmented stalk, and an obliquely oriented calyx. A well-formed hibernaculum originates from a short, lateral stolon at the base of certain zooids. The calyx bears a rigid shield with a conspicuous aboral carina extending along the entire length. Colonies have been found only in fully freshwater habitats and appear not to tolerate salinities higher than 1.0 ppt.  相似文献   

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Remipedia is one of the most recently discovered classes of crustaceans, first described in 1981 from anchialine caves in the Bahamas Archipelago. The class is divided into the order Enantiopoda, represented by two fossil species, and Nectiopoda, which contains all known extant remipedes. Since their discovery, the number of nectiopodan species has increased to 24, half of which were described during the last decade. Nectiopoda exhibit a disjunct global distribution pattern, with the highest abundance and diversity in the Caribbean region, and isolated species in the Canary Islands and in Western Australia. Our review of Remipedia provides an overview of their ecological characteristics, including a detailed list of all anchialine marine caves, from which species have been recorded. We discuss alternative hypotheses of the phylogenetic position of Remipedia within Arthropoda, and present first results of an ongoing molecular-phylogenetic analysis that do not support the monophyly of several nectiopodan taxa. We believe that a taxonomic revision of Remipedia is absolutely essential, and that a comprehensive revision should include a reappraisal of the fossil record.  相似文献   

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Ecosystem transformation and depletion of natural resources by human activity with associated increase in species extinctions renders research to understand the consequences of these transformations and design strategies to conserve biological diversity a fundamental priority. Since the introduction of the term biodiversity, accumulated research in this field has expanded exponentially. An analysis of existing literature was conducted to examine patterns in the resulting research effort. The analysis, conducted using the Web of Science (WoS), identified 13336 published articles between 1987 and 2005 concerning biodiversity research. Research efforts are increasing, with 72% of the research effort addressing terrestrial ecosystems. Most of the research is experimental in nature, with few models developed, and focuses on species. Despite constant technical improvements, research on genetic diversity still represents a minor component. Research on different systems is disseminated through different publication outlets, fragmenting the community and derived knowledge. Reported results, here measured as strength of the correlation between biodiversity and ecosystem function, do not differ across ecosystems but are stronger when the study focused on functional groups instead of species level. Collaborative efforts remain limited, as the average number of authors per paper is not increasing with time, unlike patterns in other disciplines. The international distribution of research efforts is highly skewed, with the USA and the EU conducting nearly 90% of the research.  相似文献   

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Seven species and one sub-species of Mecoptera are aquatic as larvae and pupae. All aquatic species are classified in two genera of the family Nannochoristidae and have very restricted geographic ranges, with three species confined to extreme southern South America, three species and one sub-species confined to New South Wales or Tasmania in Australia, and one species confined to the South Island of New Zealand. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment  相似文献   

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Duin D  van Besselaar P 《ZooKeys》2011,(150):193-210
The research environment of scholars is increasingly web-based. This makes it urgent to study the effects of moving to the Web on research practices, scholarly output and innovation. We propose a theoretical framework and a methodology to study these effects. In a pilot study, we apply theory and method on an online community in biodiversity research, to demonstrate the feasibility of the approach. We also indicate the practical relevance of this kind of analysis for improving the quality of virtual research environments. In the last section, directions for further research are suggested.  相似文献   

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微孢子虫生物多样性研究的述评   总被引:4,自引:0,他引:4  
刘吉平  曾玲 《昆虫知识》2006,43(2):153-158
微孢子虫作为一类专营细胞内寄生的低等的原生动物,有着比较悠久的进化历史。微孢子虫是一种既具有真核生物特征又具有原核生物特征的生物,同样具有生物多样性的本质,文章尝试用生物多样性的概念和原理,阐述原始的真核寄生物微孢子虫的物种多样性、遗传多样性和生态系统多样性的研究概况。  相似文献   

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The sub-discipline of biodiversity and ecosystem functioning (BEF) has emerged as a central topic in contemporary ecological research. However, to date no study has evaluated the prominence and publication biases in BEF research. Herein we report the results of a careful quantitative assessment of BEF research published in five core general ecology journals from 1990 to 2007 to determine the position of BEF research within ecology, identify patterns of research effort within BEF research, and discuss their probable proximal and historical causes. The relative importance of BEF publications increased exponentially during the period analyzed and was significantly greater than the average growth of ecological literature, affirming the prominence of BEF as a current paradigm in ecology. However, BEF research exhibited a strong bias toward experimental studies on terrestrial plant communities, with significantly lower effort devoted to the functional aspects of biodiversity in aquatic systems, multiple trophic level systems, and animal or microbial communities. Such trends may be explained by a combination of methodological adequacy and historic epistemological differences in ecological thinking. We suggest that BEF researchers should direct more effort toward the study of aquatic systems and animal communities, emphasize long-term and trophically complex experiments, such as those with multi-trophic microbial communities, employ larger-scale field observational studies and increase the use of integrative and theoretical studies. Many technical and analytical methodologies that are already employed in ecological research, such as stable isotopes, paleobiology, remote sensing, and model selection criteria, can facilitate these aims. Overcoming the above-mentioned shortcomings of current BEF research will greatly improve our ability to predict how biodiversity loss will affect ecosystem processes and services in natural ecosystems.  相似文献   

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