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金缕梅类科的系统发育分析 总被引：1，自引：0，他引：1
本文运用分支分类的方法对金缕梅类进行了系统发育的分析。金缕梅类作为单元发生群包括下
列19科：昆栏树科、水青树科、连香树科、领春木科、杜仲科、金缕梅科、悬铃木科、交让木科、假槲树科、双颊果科、折扇叶科、黄杨科、西蒙得木科、木麻黄科、山毛榉科、桦木科、杨梅科、马尾树科和胡桃科。木兰科在分析中被选择作为外群类。在对大量性状进行评估之后，选择了32对性状作为建立数据矩阵的基本资料。性状极化主要以外类群比较、化石证据和通行的形态演化规律为依据。首次引入了不合谐数的概念来检测性状极化结果的正确程度，并对少数不合谐数较大的性状的极性进行了调整。采用最大同步法、最小平行进化法和综合分析法进行运算，按照最简约的原则，选出演化长度最短的谱系分支图，作为本文讨论的基础，并在此基础上，探讨了金缕梅类科的系统关系。 相似文献
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徐克学 《中国科学院研究生院学报》1989,27(3):232-239
本文讨论数量分支分类，提出一种构造演化树的实际计算方法，称为最大同步法。桔梗科6个种的数据作为例子进行说明，并对这种方法做简单的评论和比较。 相似文献
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徐克学 《中国科教创新导刊》2012,(30):216-216
在紧张的考场环境中,很多学生写作文时,不知如何去写开头和结尾,导致作文质量不高。因此,写好开头结尾至关重要。 相似文献
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徐克学 《中国科学院研究生院学报》1982,20(4):502-509
In this paper, the various mathematical methods applied to taxonomy are intro-
duced to readers. Some approaches to the classification induced by statistics, graph
theory, information theory, fuzzy mathematics are discussed. An example of classifica-
tion (6 OTU’s with 8 characters) is given for convenience of discussion. The original
data matrix of this example is obtained from 6 species in the family of Campanulaceae.
相似文献
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徐克学 《中国科学院研究生院学报》1993,31(6):578-586
本文是“分支分类的一种计算方法—最大同步法”一文的姐妹篇。两种方法运算过程基本相同,
不同之处乃是最小平行进化法利用平行进化的概念,首先确立两个分支单位相结合时产生平行进化
的步数,即平行进化系数的计算公式,对所有待结合分支单位间计算平行进化系数。然后根据俭约性
原理,要获得最俭约演化树谱图,应该尽可能减少平行进化,也就是说在选择结合的分支单位时,
选择平行进化系数最小者优先结合。于是建立起一种新的分支分类运算方法。两种方法的思路完全不
同,从原理上讲对某些数据,最小平行进化法优于最大同步法,但后者运算量较大。如果将两种思路
兼顾,可以得出由这两种方法相结合而产生平行同步综合法．桔梗科6个种的数据作为例子进行运算说明。 相似文献
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研究全世界鹅观草属只Roegneria C．Koch中绝大多数种类与其有关属(冰草属、披碱草 属、偃麦草属及赖草属)的外部形态、解剖、细胞等30个性状，应用相关系数抑或距离系数以及各种聚类方法组合所得出的树系图，均明确显示鹅观草属应归入披碱草属。 相似文献
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中国散生竹类的数量分类和确定分类等级的探讨 总被引：1，自引：0，他引：1
In this paper, 21 species representing 13 genera were studied by means of humeri-
cal taxonomic methodes. One geographical and 52 morphological characters were used.
The correlation coefficients were computed by standardized data, and the various clus-
tering methods were performed on the correlation matr x. The UPGMA clustering
method was selected as the optimal one and its results were shown in the form of
dendrograms.
We present a simple method to construct the joint and broken lines by which the
boundary of the genera, subtribes and tribes in the dendrogram is determined.
By means of numerical taxonomic methods, we can easily work out a systematic
dendrogram and the following taxonomic treatments are easily proposed:
(1) Sasamorpha sinica (Keng) Koidz. should be reffered to the genus Sasa Makino
& Shibata.
(2) Pseudosasa amabilis (McClure) Keng f. should belong to the genus Pseudosasa
Makino and should not be referred to the genus Arundinaria Michaux.
(3) The genus Brachystachyum Keng should be considered as a separate one.
(4) The genus Pleioblastus Nakai should not be combined with the genus Arun-dinaria Michaux, but kept as an independent one. 相似文献
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In this paper, 10 species and varieties of the genus Panax from China were
studied by means of numerical taxonomic methods. At first, the geometric approaches
and statistical treatments were used and some new characters induced by the funda-
mental characters were defined for the numerical representation of the morphological
characters of plants. Consequently, forty-seven morphological, three chemical, one geo-
graphical and one cytological characters were adopted. The principal component ana-
lysis and the similarity coefficients were computed on the standardized data. Based
upon the correlation matrix and the distance matrix respectively, the Q and R cluster
analyses were carried out, and UPGMA was used in both Q and R cluster analyses.
According to the R cluster analysis, all characters are mainly divided into 5 sets:
A, B, C, D and E (Fig. 2). The tree-like diagram illustrates that chemical constitu-
ents of triterpenoids and the chromosome numbers are related to some morphological
characters, such as the roots, the rhizomes, the seeds and the leaves. It is of interest to
note that the thicker the fleshy roots, the larger the seeds and the wider the teeth of
leaflet, the higher the content of the tetracyclic triterpenoids of dammarane type it
contains. On the other hand, the Q cluster analysis showed that Panax as a whole
may be divided into two groups (Fig. 3). The first group includes P. ginseng, P.
quinquefolius, P. notoginseng and P. zingiberensis and the second group includes P.
stipuleanatus, P. pseudo-ginseng, P. japonicus var. japonicus, P. japonicus var. angus-
tifolius, P. japonicus var. major and P. japonicus var. bipinnatifidus. The results of
the computation of principal component analysis indicate that the first principal
component consistes of the characters occurring in the sets A and B. It shows that
the variation in Panax has two opposite directions. One of them, corresponding to the
set A, is represented by the first group, and the other, corresponding to the set B, is
by the second group. Finally, some questions about the use of the genus in medicine were discussed. 相似文献
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