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At present biological systematics, i. e. classification and identification of organisms, is also a subject of the employment of mathematical methods. The topic of this paper is identification. One of the most important methods of identification is that by means of keys. Therefore a short review on the types of keys and their valuation is represented. Moreover there are discussed the essential properties of keys: reliability and velocity of identification. Further in connection with these two quantities probabilistic models are treated. The last part of the article deals with the optimization of keys concerning theory and practice of the problem. 相似文献
354.
The known chemistry of subtribe Eupatoriinae, tribe Eupatorieae, Asteraceae, is reviewed critically and taxonomic implications are discussed. 相似文献
355.
《Fungal Ecology》2015
Fungal endophytes are species rich and ubiquitous, yet, apart from the genus Epichloë, their ecology is largely unknown. Here we explore how herbivores affect the diversity of fungal endophytes in tundra grasslands. We assess both hyphal morphological and taxonomic diversity in grass individuals.By microscopic examination we identified endophytes to be present in all sampled grass individuals whereas identification to taxonomic units were only achieved in a subset of the individuals using laser micro dissection pressure catapulting and culturing for endophyte isolation. Hyphal morphological diversity was significantly higher in grasses exposed to grazing, along with 45 % more taxonomic units achieved.Our results suggest that grazing is an important mediator of fungal endophyte diversity in tundra grasslands. Furthermore, we suggest laser dissection of stained endophytes as a method for further exploring the ecological role of fungal endophytes. 相似文献
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357.
The use of ants and other soil and litter arthropods as bio-indicators of the impacts of rainforest clearing and subsequent land use 总被引:4,自引:0,他引:4
Akihiro Nakamura Carla P. Catterall Alan P. N. House Roger L. Kitching Chris J. Burwell 《Journal of Insect Conservation》2007,11(2):177-186
The present study investigated the impacts of rainforest clearance, and associated subsequent land␣use for pasture, on assemblages
of soil and litter arthropods in eastern subtropical Australia. We assessed the utility of soil and litter arthropods as potential
bio-indicators of cleared and forested habitats. Arthropods were sampled from 24 sites (12 sites each in rainforest and pasture)
using two methods (extraction from litter, pitfall traps). Responses of taxa were analysed at various levels of taxonomic
resolution, including ‘coarse’ arthropods (all arthropods sorted to Order/Class), ant genera and ant species. Multivariate
analyses of arthropod composition indicated that an increase in the level of taxonomic resolution did not provide a commensurate
increase in the sensitivity of assemblage response. Indicator values (IndVals), computed for each taxon, showed that a number
of arthropod taxa may have potential as bio-indicators of habitat change. However the use of many of these, especially many
ant species found in our study, may be unreliable because even after extensive numbers of sites were sampled, most species
showed patchy distributions. To overcome this problem, we generated ‘composite indices’, by combining information from sets
of indicator taxa. The utility of these composite indices is discussed. 相似文献
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359.
From polluted water of a lagoon pond a new type of denitrifying photosynthetic purple bacteria was isolated. With respect to morphology, fine structure, photopigments, requirement for growth factors, the range of utilization of organic substrates for phototrophic growth and DNA base ratio, the denitrifying strains show the closest resemblance to Rhodopseudomonas sphaeroides and were therefore described as a subspecies named R. sphaeroides forma sp. denitrificans. The new isolates grow well with nitrate anaerobically in the dark accompanying the evolution of nitrogen gas. They cannot assimilate nitrate as the nitrogen source for growth. 相似文献