排序方式: 共有38条查询结果,搜索用时 15 毫秒
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侯林 《应用与环境生物学报》1998,4(1):40-43
对中国两性生殖卤虫12个品系的10个品系形态特征进行了聚类分析和主成分分析,并与A.urmiana进行了比较研究.研究结果表明,A.urmiana和中国两性生殖卤虫各品系明显可分为2个类群,证明中国各两性生殖卤虫品系均属于A.sinica.而A.sinica不属于A.urmiana.在中国两性生殖卤虫各品系中NL、HJQ、SB可分为另一类群,显示可能存在种下分类阶元.本文所选取的形态特征是稳定的,可做为卤虫品系形态特征数值分类的重要依据. 相似文献
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左家哺 《湖南环境生物职业技术学院学报》2001,7(2):70-73
邹惠渝和张凤春两位先生所撰写的"长苞铁杉和铁杉属数量分类的研究"一文(见<南京林业大学学报>,1996,20(1)43~47),至少存在以下3个问题值得商榷一是取材欠完整,二是聚类方法单一,三是结合线计算错误.据本文重新核算,<邹文>的结论有误. 相似文献
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Taxonomic Exaggeration and Its Effects on Orchid Conservation 总被引:1,自引:0,他引:1
Abstract: Orchids are the largest family of flowering plants, encompassing several times as many species as birds or mammals. Because of their diversity, charisma, and threats from overcollection and habitat loss, they are a key group in conservation. Nevertheless, preservation of this group is plagued by taxonomic problems, particularly in Europe, where new taxa are actively being described. We used a checklist of orchids to compare the taxonomic treatment of this family between Europe and neighboring areas to search for geographical patterns. Numbers of invalid, infraspecific, and hybrid names are significantly higher in Europe than in surrounding areas. Recognition of numerous and poorly circumscribed orchid taxa is a serious obstacle to their conservation because rare, poorly defined species may be prioritized for conservation over taxonomically "good" species. This phenomenon may be the result of the popularity of orchids in Europe. We believe that more taxonomic effort should be made in other areas of the world (e.g., the tropics) and on less charismatic groups. 相似文献
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Wesley M. Knapp Anne Frances Reed Noss Robert F. C. Naczi Alan Weakley George D. Gann Bruce G. Baldwin James Miller Patrick McIntyre Brent D. Mishler Gerry Moore Richard G. Olmstead Anna Strong Kathryn Kennedy Bonnie Heidel Daniel Gluesenkamp 《Conservation biology》2021,35(1):360-368
Extinction rates are expected to increase during the Anthropocene. Current extinction rates of plants and many animals remain unknown. We quantified extinctions among the vascular flora of the continental United States and Canada since European settlement. We compiled data on apparently extinct species by querying plant conservation databases, searching the literature, and vetting the resulting list with botanical experts. Because taxonomic opinion varies widely, we developed an index of taxonomic uncertainty (ITU). The ITU ranges from A to F, with A indicating unanimous taxonomic recognition and F indicating taxonomic recognition by only a single author. The ITU allowed us to rigorously evaluate extinction rates. Our data suggest that 51 species and 14 infraspecific taxa, representing 33 families and 49 genera of vascular plants, have become extinct in our study area since European settlement. Seven of these taxa exist in cultivation but are extinct in the wild. Most extinctions occurred in the west, but this outcome may reflect the timing of botanical exploration relative to settlement. Sixty-four percent of extinct plants were single-site endemics, and many occurred outside recognized biodiversity hotspots. Given the paucity of plant surveys in many areas, particularly prior to European settlement, the actual extinction rate of vascular plants is undoubtedly much higher than indicated here. 相似文献
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Ziyan Qin Qun Gao Qiang Dong Joy D. Van Nostrand Qi Qi Yifan Su Suo Liu Tianjiao Dai Jingmin Cheng Jizhong Zhou Yunfeng Yang 《Frontiers of Environmental Science & Engineering》2022,16(3):32