濒危种裂叶沙参种群生命表和存活曲线的研究及其与广布种泡沙参的 …

以近缘广布种泡沙参为对照,本文编制了濒危种裂叶沙参种群的标准生命表,存活曲线以及海拔２３００￣２４００ｍ、２７００￣２９００ｍ、２９００￣３１００ｍ和３１００￣３４００ｍ区域４个种各的生命表,存活曲线。根据其生活史,讨论了裂叶沙参各种群特定年龄的存活量,死亡量和死亡率等重要参数,裂叶沙参种群存活曲线属ＤｅｅｖｅｙＣ型,１￣５年生死亡率最高,个体最长寿命２５年,而泡沙参种群的死亡高峰期是１￣３年,个     

濒危种裂叶沙参种群生命表和存活曲线的研究及其与广布种泡沙参的对照

以近缘广布种泡沙参为对照,本文编制了濒危种裂叶沙参种群的标准生命表、存活曲线以及海拔２３００～２４００ｍ、２７００～２９００ｍ、２９００～３１００ｍ和３１００～３４００ｍ区域４个种群的生命表,存活曲线。根据其生活史,讨论了裂叶沙参各种群特定年龄的存活量、死亡量和死亡率等重要参数。裂叶沙参种群存活曲线属ＤｅｖｅｙＣ型,１～５年生死亡率最高,个体最长寿命２５年。而泡沙参种群的死亡高峰期是１～３年,个体最长寿命２１年。导致裂叶沙参种群幼龄个体死亡的内在原因是其较弱的抗逆性和适应能力;外在原因是严重的干旱、外界干扰和群落内的光照不足。裂叶沙参种群适应不良环境的能力较泡沙参弱：在海拔２７００ｍ以下地区,由于外界干扰和环境干旱,除水份条件较好的特殊生境,大多种群呈严重衰退趋势,不能满足编表条件,只有海拔２７００ｍ以上区域的种群呈稳定或扩展趋势;而泡沙参各种群在不同海拔区域均呈稳定或扩展趋势,满足编表条件。从海拔２３００ｍ到３４００ｍ,不同裂叶沙参种群个体寿命呈：短长短的格式,与外界严酷较好严酷的环境相对应。这表明裂叶沙参种群在严酷环境条件下改变了其生存对策,缩短了个体寿命。     

裂叶沙参与泡沙参解剖生态学的比较研究

借助于光镜和扫描电镜,系统观察了濒危植物裂叶沙参(Adenophora lobo-phylla Hong.)的根、芦头、茎和叶的解剖特征及茎、叶、种子的表面形态特征,并将有关性状与广布种泡沙参(A.potaninii Korsh.)作了对比研究。结果表明,两种沙参在叶表皮细胞形状,垂周壁式样,角质层初级雕纹及次级雕纹;叶片气孔形状及外拱盖外缘纹饰及内缘形状,保卫细胞上角质层薄厚及蜡质纹饰;叶表毛状体形状及纹饰,茎中皮层占茎横切面的比例;茎中有无髓纤维等方面存在着明显差异。相对于泡沙参,裂叶沙参单株叶面积大,生物量高,表皮角质层薄,单位面积内被毛数量少,栅栏组织薄,气孔周围蜡质沉积颗粒少;茎的直径大,皮层较薄等。这些特征表明裂叶沙参对旱生生境适应能力弱,而泡沙参对旱生生境适应能力强。     

裂叶沙参和泡沙参种群有性生殖和无性繁殖的比较

通过对裂叶沙参(Adenophora lobophylla Hong)和泡沙参(A.potaninii Korsh.)种群有性生殖和无性繁殖特性的对比,揭示濒危植物裂叶沙参的种群内部致濒机制。结果表明:裂叶沙参种群幼苗抢占草本层上层空间能力弱于泡沙参种群;裂叶沙参种群是以相对长的生殖期和高产籽量来适应环境;裂叶沙参种群开花结实量虽高于泡沙参种群,但其中成熟种子少,种子质量差,致使其种群由种子到一年生幼苗的转化率极低,并且幼苗生活力弱,是导致其种群濒危的重要内部原因。裂叶沙参种群除有性生殖外还兼有较弱的无性繁殖,是对其有性生殖的一个重要补充。     

裂叶沙参与泡沙参剖解生态学的比较研究

借助于光镜和扫描电镜,系统观察了濒危植物裂叶沙参（Ａｄｅｎｏｐｈｏｒａ ｌｏｂｏ－ｐｈｙｌｌａ Ｈｏｎｇ）的根、芦头、茎和叶的解剖特性及茎、叶、种子的表面形态特征,并将有关性状与广布沙参（Ａ．ｐｏｔａｎｉｎｉｉ Ｋｏｒｓｈ．）作了对比研究。结果表明,两种沙参在叶表皮细胞形态,垂周壁式样,角质层初级雕纹及次级雕纹;叶片气孔形状及外拱盖外缘纹饰及内缘形状,保卫细胞上角质层薄厚及蜡质纹饰;叶表毛状体形状     

遮光条件下裂叶沙参和泡沙参气孔行为的对比研究

通过遮光实验研究了裂叶沙参（Ａｄｅｎｏｐｈｏｒａ ｌｏｂｏｐｈｙｌｌａ）和泡沙参（Ａ．ｐｏｔａｎｉｎｉｉ）叶片的气孔行为,比较了不同遮光处理对裂叶沙参和泡沙参气孔的生理特性以及生态适应的影响。结果表明：裂叶沙参对不同遮光处理的适应性较差,相反,泡沙参具有较强的适应性和抗逆性;在自然光照和轻度遮光条件下,中午时泡沙参叶片的孔开度逐渐减小和部分气关闭;裂叶沙参光合作用的非气孔限制占主要地位,泡沙参光合     

裂叶沙参和泡沙参气孔行为与蒸腾特性的关系

采用LI-6400便携式光合分析系统对裂叶沙参和泡沙参进行了不同遮光水平蒸腾速率的测定,并同步测定了叶片气孔大小、气孔密度、气孔开度和气孔导度等气孔行为.采用相关系数和通径系数分析方法分析了不同遮光水平裂叶沙参和泡沙参气孔行为与蒸腾特性的关系.结果表明:不同遮光水平测定的气孔行为对裂叶沙参和泡沙参蒸腾作用的直接影响大致相同,其中,两种沙参的气孔密度对蒸腾速率的直接影响较大.但泡沙参的气孔导度与蒸腾作用具有极显著的相关关系.     

遮光条件下裂叶沙参和泡沙参气孔行为的对比研究

通过遮光实验研究了裂叶沙参(Adenophora lobophylla)和泡沙参(A. potaninii)叶片的气孔行为,比较了不同遮光处理对裂叶沙参和泡沙参气孔的生理特性以及生态适应的影响。结果表明:裂叶沙参对不同遮光处理的适应性较差,相反,泡沙参具有较强的适应性和抗逆性;在自然光照和轻度遮光条件下,中午时泡沙参叶片的气孔开度逐渐减小和部分气孔关闭;裂叶沙参光合作用的非气孔限制占主要地位,泡沙参光合作用的气孔限制较明显。     

裂叶沙参与泡沙参种群分布格局分形特征的分析

 裂叶沙参与泡沙参种群在不同海拔区域分布格局的计盒维数与其在群落中占据空间的能力成正比,并且与环境因素密切相关。在裂叶沙参与泡沙参种群较为适生的区域,海拔2700～3100m,两者在群落中占据空间的能力最强,他们的计盒维数达到最高。在低于海拔2700m或高于海拔3100m,环境条件严酷的区域,裂叶沙参种群与泡沙参种群占据空间的能力不同程度的下降。在不同的海拔区域,广布种泡沙参种群占据空间的能力均比裂叶沙参种群高,而其受环境因素影响较弱。在海拔2700m以下地区,泡沙参种群水平分布格局的计盒维数比裂叶沙参种群高4.5倍;在两种群较为适生的区域,海拔2700～3100m,泡沙参计盒维数比裂叶沙参种群高1.5倍,差异最小;在泡沙参与裂叶沙参种群分布的上限,海拔3100m以上地区,两者计盒维数差异又增加,泡沙参计盒维数比裂叶沙参种群高1.8倍。这说明裂叶沙参种群的内在适应力、竞争力比泡沙参种群相对较弱。     

濒危植物裂叶沙参种群生殖力表的研究

本文分别以当年产种子数量和一年生幼苗数量为基础,编制了裂叶沙参种群(总和)和海拔2300-2400m, 2700-2900m, 2900-3100m, 3100-3400m 4个不同海拔区域种群的生殖力表,分析了不同种群两种生殖表的种群内禀增长率(r_m),周限增殖率(λ),净增长率(R₀),毛增长率(G)等动态参数与种群动态的关系;比较了两种生殖力表的特点和利弊;讨论了裂叶沙参种群生殖生态学特性和种群发展趋势及其与环境因素的关系。以种子数量为基础编制的生殖力表的各种群动态参数表明,裂叶沙参具有较强的产生种子的能力,特别是在生境条件较好的海拔2700-3100m区域,种群个体结实量可达到很高的水平。以一年生幼苗数量为基础编制的生殖力表表明,裂叶沙参种群从整体上呈衰退趋势。但不同种群间存在差异:在海拔2300-2400m,水份条件较好的特殊生境和海拔2900-3100m的种群呈稳定特征;而海拔2700-2900m,3100-3400m的种群呈缓慢衰退特征。以种子数量为基础编制的生殖力表可以反映裂叶沙参种群产生种子的能力和生殖生态学特征;而以一年生幼苗数量为基础编制的生殖力表包含了种子库的生态学过程,能较好的反映种群动态特征。在实践中,两种生殖力表应配合使用,才能全面刻划种群生殖生态学和种群动态特征。     

Comparative Studies of Sexual Reproduction and Asexual Propagation Between Populations of Adenophora lobophylla and A. potaninii

To reveal the internal mechanism which lead to the endangerment of the AdenophoUa lobophylla Hong population, comparative studies of sexual reproduction and asexual propagation between the populations of A. lobophylla and A. potaninii Korsh were carried out. Young seedlings of A. lobophylla had less ability to occupy the uper space of the herbaceous layer than those of A. potaninii. The A. lobophylla population produced much more seeds and lived a long reproductive life to adapt the ambient environment. Though the number of flowers and fruits of A. lobophylla population was more than those of A.potaninii population, the number of its ripe seeds as well as the quality was less. Thus, the development rate from its seeds to one-year old seedlings was very low, and viability of its young seedlings was very poor. This could be the important factor causing the imminent population endangerment of A. lobophylla. Besides the sexual reproduction, the A. lobophylla population also had a comparatively tiny ability of asexual propagation, which was advantageously complementary to its sexual reproduction.     

Sporogenesis and Gametogenesis of Endangered Adenophora lobophylla Hong (Campanulaceae)

Reported in this paper are the microsporogenesis, megasporogenesis and the development of male and female gametophytes of the endangered species Adenophora lobophylla. The anther is four-sporangiate with its wall composed of four layers: epidermis, fibrous endothelium, middle layer and glandular tapetum of binucleate cells. The cytokinesis of microspore mother cell in meiosis is simultaneous, and tetrads are tetrahedral. Pollen grains are 2-celled at the dispersal stage. Ovule is anatropous, unitegmic and tenuinucellate with a hypodermal archesporial cell developing directly as the megaspore mother cell which undergoes meiotic division and then forms a linear tetrad. The embryo sac is of Polygonum type. The polar nuclei fuse before fertilization. An endothelium differentiates when the uninucleate embryo sac forms. Comparative studies were made with the closely related and widely distributed species A. potaninii. No differences between them were found. No obstacle to sexual reproduction in this endangered species was observed. As a conclusion, no endangering factors were found to influence the sporogenesis and gametogenesis of A. lobophylla. According to our observision and the references on embryological studies of the Campanulaceae(s. l. ), there is no evident differentiation in sporogenesis and gametogenesis in this family.     

Biosystematic Studies on Adenophora potaninii Korsh. Complex (Campanulaceae) III. Genetic Variation and Taxonomic Value of Morphological Characters

Adenophora potaninii Korsh．complex is a morphologically variable group including six species．As shown in many species in the genus Adenophora,the variability of many morphological characters in the complex under investigation is amazingly great,which brings difficulties in the delimitation and indentification of taxa．In the present study,six populations representing five species in the complex were systematically sampled to investigate the pattern of morphological variation within population and to detect the genetic basis of the variation with progeny tests and controlled crosses．The results are as follows： Great morphological variation within population is found (Fig.1),including characters such as leaf shape,teeth number and size of leaf margins,teeth number of calyx lobes,and indumentum on the surface of stems and leaves,which were previously considered as diagnotic．Systematic sampling and statistical analysis show that the differences in the above characters exhibit continuous patterns of variation within population (Fig．1,2),though they are highly correlated (Table 2)．From progeny testing and crossing between two contrast types of individuals (oblong,dentate and pubescent leaves vs．narrow,entire and glabrous leaves)it is evident that those characters show continuous variability in segregating progenies (Fig.3,4)and appear to be influenced by large numbers of loci with individually slight effects．Since most wild populations were highly heterozygous for those characters,the individuals in one extreme of variation can produce their variable offsprings including individuals similar to those in the other extreme (Fig. 3). This is also true for the indumentum density on stems and teeth number of calyx lobes. In this complex, A. biformifolia Y. Z. Zhao, A. bockiana Diels and A. polydentata P.F. Tu et G. J. Xu were described exclusively based on leaf shapes, teeth number of leaf margins and calyx lobes, teeth size of leaf margins, and indumentum on the surface of stemsand leaves. It is demonstrated, however, that the variation of those characters is of a quantitative nature and show no discontinuities. As a result, genetic analysis of diagnostic characters along with their sympatric distribution and same habitats, strongly suggest that A.biformifolia as well as A. bockiana and A. polydentata are actually the extreme individuals within A. wawreana and A. potaninii respectively and should not be recognized as taxa at any taxonomic level.     

A Reevaluation of the Status of A. lobophylla Based on ITS Sequence,with Reference to the Utility of ITS Sequence in Adenophora

Adenophora Fisch. (Campanulaceae)is a medium-sized and diverse genus, which occurs mainly in eastern Asia, particularly in China. Although several taxonomic systems have been proposed, there is still much debate on the delimitation and systematic arrangement of the species within the genus, due mainly to high variation in morphology, habitats, phenotypic plasticity, and potential hybridization. A. lobophylla Hong is a rare perennial endemic to several counties of Sichuan, China. Since this species was recognized, much work has been done on its taxonomic status, including morphology, crossing experiment and allozymes. However, evidence available is not concordance so far, and its relationship with other species within the genus remains largely uncertain. In the present paper, the internal transcribed spacer(ITS) region of 18s～26s nuclear ribosomal DNA was sequenced in 10 representatives of Adenophora and two outgroup species of Campanula to assess its utility for phylogenetic reconstruction in Adenophora, in addition to reevaluation of the taxonomic status of A. lobophylla. The results indicate that there exist high sequence alignability and length conservation among ITS sequences, with informative sites being 3.9% and length ranging from 539 to 541 bp and G + C content varying from 57% to 60%. Phylogenetic　analyses using Fitch parsimony show that A. lobophylla is closely related to A. himalayana instead of A. potaninii or A. stenanthina as revealed by previous morphological work and crossing experiment. The ITS phylogeny is generally congruent with other evidence in that A. lobophylla should be removed from the A. potaninii complex or even subsect. Microdiscus. Its appropriate placement, however, should be further explored. In pairwise comparisons at unambiguously aligned sites, sequence divergence was relatively low among Adenophora species with the values ranging from 0.0 to 3.9% in spite of the fact that the species surveyed covered all of the sections and subsections of the genus. In contrast, high sequence divergence is found among Adenophora and Campanula species with the values from 17.8 % to 19.2 %. The low divergence among Adenophora species is justified considering its recent origin, and also suggests that ITS sequence would provide a promising source of nuclear phylogenetic markers to reconstruct the phylogeny within Campanulaceae on the tribe and family levels.     

Gas Exchange and Water Use Efficiency of Adenophora lobophylla (Campanulaceae) at Different Altitudes on the East Boundary of the Qing- Zang Plateau

Field measurements were made of leaf net photosynthetic rate (Pn), apparent quantum yield (AQY), dark respiration (Rd), transpiration (Tr), water use efficiency (WUE), stomatal conductance (Gs), intercellular CO2 concentration (Ci), leaf temperature (TI), stomatal density, air temperature (Ta) and relative soil water content (SWC) for Adenophora lobophylla Hong in August, 1996. The species grows in the region from an altitude of 2 300 m to 3 400 m on the eastern boundary of the Qing-Zang Plateau in Sichuan Province, China. Leaf gas exchange, water use efficiency and plasticity of populations in field were compared among different altitudes to evaluate the possible interactions between adaptation of A. lobophylla and environmental factors in these habitats. Pn and AQY at low altitudes were lower than those at high altitudes. They strongly responded to SWC and Ta. On the other hand, Rd at low altitudes was higher than that at high altitudes because of the higher air temperature there. The growth rates at low altitudes were associated with the increases in Rd and a relevant less Pn. Stomata showed strong responses to leaf-to-air vapor pressure deficit at the leaf surface (Vpdl) and Tl in these habitats. Increasing stomatal limitations to photosynthesis appeared to be responsible for the reduction in Pn at high Tl, Vpdl and low available soil water for A. lobophylla at low ahitudes. Nonstomatal limitation to photosynthesis also happened at extreme soil water deficits and high Tl and Vpdl at an altitude of 2 300 m. Tr had a close relationship with stomatal conductance and was also affected by leaf temperature and leaf-to-air vapor pressure deficit at the leaf surface among habitats grown in different ahitudes. WUE increased with altitude. Increasing stomatal densities showed different plasticity of A. lobophylla as altitude increased. SWC and Ta appeared to be important factors to limit carbon assimilation in A. lobophylla at low altitudes, primarily through the process of stomatal closure. The overall results are in consistence with the hypothesis that strong pressure from tmfavorable environmental factors to gas exchange and wateruse of A. lobophylla may prevent their population expansion at low altitudes, which indicate that the above-mentioned restrictions might lead to the endangerment of A. lobophylla.     

The Morphological Variation and the Karyotypical Characters of Dendranthema indicum and D. lavandulifolium

Dendranthema indicum L. and D. lavandulifolium (Fisch. ex Trautv. ) Ling et Shih are two species which are greatly variable in morphology. The specimens collected from different habitats show distinct variation in characters such as leaf division、 leaf pubescence、 size of capitula and number of capitula. Some authors (Li 1983; Du 1989; Nakata 1987)have studied the chromosome numbers and karyotypes of D. indicum and D. lavandulifolium and reported the basic chromosome number and polyploidy of these two species. But some questions, such as the patterns and trends of morphological variation, the relationships between morphological and karyotypical variations and the phylogenetic relationship between D. indicum and D. lavandulifolium remain unclear . Based on wide field investigation and cultivation experiments, the present authors made a thorough study on D. indicum and D. lavandulifolium from morphology、 cytology with reference to geographical distribution and habit conditions. The results show that the amount of leaf pubescence of D. indicum is closely related to the water content in its habitat; the diameter of capitula decreases, while the number of capitula of D. lavandulifolium increases with the increase in elevation. Comparing the karyotypical constitution of different populations of D. indicum and D. lavandulifolium, the authors infer that natural hybridization, both intraspecific hybridization and hybridization between D. indicum and D. lavandulifolium, has played an important role in the origin of polyploids and in the evolutionary process of karyotypes of D. indicum and D. lavandulifolium. By a synthetic analysis from morphology, cytology and geography, the authors also suggest that D. indicum and D. lavandulifolium be sister species, derived from a common ancestor, and it is unreasonable to consider one of themevolved from the other.     

鮈亚科鱼类下咽骨和下咽齿的形态差异及其功能适应

采用双筒解剖镜观察和手工绘图的方法,研究鮈亚科鱼类39个代表种下咽骨和下咽齿的形态特征,分析鮈亚科鱼类下咽骨和下咽齿的形态差异及其功能适应。结果显示,鮈亚科鱼类的下咽骨可以分为粗壮型、中间型和狭长型3种形态类型;下咽齿可以分为圆锥型、臼齿型、粗壮侧扁型、侧扁型和极侧扁型5种形态类型。鮈亚科鱼类下咽骨和下咽齿间呈现出多种形态组合,并相互配合共同处理不同类型的食物。下咽骨和下咽齿的形态差异为鮈亚科鱼类摄食不同类型的食物、充分利用不同的生境资源在摄食器官多样性方面提供了保证。     

安徽羽叶报春核心和边缘居群的形态变异比较研究

为了解濒危二型花柱植物安徽羽叶报春(Primula merrilliana)居群的形态变异,对其4个核心居群和3个边缘居群的14个形态性状进行了比较研究。结果表明,核心居群形态性状的变异系数为0.09~0.50,边缘居群为0.05~0.56,变异幅度两者间差异不明显;核心居群有8个性状的均值显著高于边缘居群(P0.05),仅有3个性状(花冠直径、花瓣宽和叶宽)为边缘居群高于核心居群。核心居群两型花间的互惠指数较高也较稳定(0.83~0.90),花型间互惠程度较高,而边缘居群的互惠指数差异较大(0.60~0.93),不同居群的互惠程度变化较大。因此,两型花柱植物安徽羽叶报春的形态性状变异基本支持"中心丰富模型"假说,并对其保护策略进行了探讨。