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911.
Chromosome numbers were determined for 340 plants ofCarex conica from 83 populations in Japan. Six aneuploids, 2n=32, 33, 34, 36, 37 and 38, were found. Plants with even diploid chromosome numbers 2n=32, 34, and 36 were the most common and had different geographical distributions. Individuals with 2n=32 were from islands in the Seto Inland Sea and nearby coastal areas of the Chugoku District of Honshu; those with 2n=34 were from the Kanto, Chubu and Kinki Districts of Honshu; those with 2n=36 were from the mountainous areas of Chugoku, Shikoku and Kyushu Districts. Canonical discriminant analysis of 17 morphological
characters demonstrated that the plants with 2n=32 were clearly distinct from those with 2n=34 or 36. All four aneuploids with even chromosome numbers showed normal bivalent pairing at meiotic metaphase I and probably
represent cytogenetically stable cytodemes. Plants with 2n=33 had one heteromorphic trivalent and 15 bivalents, indicating a structural mutation. At mitotic metaphase I, one chromosome
was markedly larger than the others, suggesting that the 2n=33 plants arose from 2n=34 plants by fusion of two chromsomes. The plant with 2n=37 was intermediate in morphology betweenCarex conica (2n=36) andC. morrowii (2n=38) and probably originated as an interspecific hybrid between these species. 相似文献
912.
Connections among species-abundance (i-m
i
), species-frequency (i-F
i
), and species-sample size (S
n
-n) relationships were examined on the basis of the mapping data of a natural forest in Thailand. The spatial distribution of
individual trees without any discrimination of species was nearly random. Provided that the spatial distribution of each species
was random, thei-m
i
and thei-F
i
relationship was reconstructed from each other in terms of the total number of species (S) and the total number of individuals (N) in the data. The number of species (S
n
) in a subsample consisting ofn individuals was then obtained from thei-F
i
relationship. Logarithm ofS
n
increased with logn and showed a convex curve through the origin. The values of diversity indices based onN andS(orn andS
n
) were affected by sample size. These trends were further examined on the basis of 944 data sets of biotic communities and
three mathematical models of anS-N relationship. The properties of species-area relation were discussed in the light of these results. 相似文献
913.
Clem Tisdell 《Biodiversity and Conservation》1994,3(5):419-436
The main characteristics of the dominant economic system, including the increasing use of markets and money are described. The global system has expanded trade, including international trade, and production tremendously. While this system has the potential to favour nature conservation, in practice the opposite has occurred. Difficulties raised for conservation of biodiversity by short-term economic crises such as deficits in a country's international payments, the adoption of policies for structural economic adjustment, international capital flows, international loans and foreign aid as well as debt-for-nature swaps are discussed. As explained, it is politically difficult in market economies to support nature conservation at the expense of economic growth and as more economies develop and become market economies this problem spreads. Given global interdependence of nations, an important issue is the distribution of net benefits from biodiversity conservation between developed and less developed countries. Possible distributions of benefits and related issues are discussed. In conclusion, the importance of political lobbying by nature conservation groups in developed market economies is emphasised as a means of ensuring correction of market failures. Unfortunately, no economic system is likely to prove satisfactory in itself in conserving biodiversity so political action by conservationists is always required. 相似文献
914.
马蹄香大小孢子发生及雌雄配子体形成 总被引:1,自引:0,他引:1
马蹄香(Sarumahenryi,Oliv.)花药壁的发育属双子叶型。花粉母细胞减数分裂为同时型,四分体主要为四面体形,少数为左右对称式排列。腺质绒毡层,其细胞可排列为不规则的两层,双核或多核。到单细胞花粉阶段,绒毡层细胞内切向壁上出现许多乌氏体。成熟花粉为2细胞型,圆球状,具单萌发沟。雌蕊6心皮,上部彼此分离、下部联合。倒生胚珠,双珠被,厚球心。胚囊发育蓼型。成熟胚囊为七细胞结构,但两个助细胞退化较早。 相似文献
915.
田林老山中山两类森林凋落物研究 总被引:15,自引:2,他引:13
田林老山中山两类森林凋落物研究梁宏温(广西农学院林学分院,南宁530001)StudiesontheLitterfallofTwoForestTypcsinMid—AltitudeofLaoshanMountaininTianlinCounty.¥L... 相似文献
916.
917.
918.
江西忍冬属药用植物资源 总被引:5,自引:0,他引:5
报道了江西忍冬属药用植物种类、地理分布、临床疗效、化学成分等有关情况,对该属资源的开发利用提出了合理建议。 相似文献
919.
920.
金属螯合亲和层析纯化金属硫蛋白 总被引:9,自引:0,他引:9
将二价铜离子螯合在Chelating Sepharose Fast Flow凝胶上制成亲和层析柱,锌诱导兔肝和镉诱导小鼠肝经匀浆、乙醇处理后上柱,用pH4.0的醋酸盐缓冲液平衡,再用pH5.2不同浓度的醋酸盐缓冲液分别洗脱,可得两个金属硫蛋白(MT)洗脱峰,经确定先后为MT-2和MT-1.分离方法比传统的凝胶过滤-离子交换法简单、省时,适于实验室规模分离纯化. 相似文献