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81.
夏永梅 《植物分类与资源学报》1996,18(1):1-3
山茶属Camellia植物在其进化过程中,以雄蕊不定数、在某些类群中存在心皮离生至合生的中间过渡,认为是山茶科中较原始的一属,分布于亚洲东部和东南部,中国长江以南广袤的亚热带地区是该属的现代分布中心,中南半岛和我国云南、广西南部的热带地区种类虽少,却集中了本属原始或较原始的类群和种类。本属演化上的近缘属或姐妹群——核果茶属Pyrenaria(包括石笔术属Tutcheria)分布区大致与本属相似,其原始(子房5室,心皮先端多少分离,花柱离生)的种类也分布于此,它们可能同出于一个心皮离生的古老祖先,即生长于亚洲古热带森林环境中的类似千五桠果属(Dillenia)的原始山茶科植物,上述地区是该属的早期分化中心和起源地,大约在白垩纪特提斯海(古地中海)东岸的劳亚古陆和冈瓦纳古陆接触地带由原始五桠果类植物演化而来。山茶属植物自热带亚洲起源和分化发生后,向四周辐射状扩展,在亚洲大陆,类群和种类明显表现出由南向北、从热带向亚热带分化和替代的规律。在漫长的进化过程中,经历第三纪以来地史和古气候的变迁,分化发展为具花梗和花梗强烈缩短变无便的两个演化枝,分道扬镳平行发展,两枝在演化上相似地表现出雌、雄蕊数目的减少及合生水平的提高,本属最进化的类群是分布区南界的管蕊茶组 Sect.Calpandria和广布我国亚热带林下的连蕊茶组Sect.Theopsis,前一组花丝全部合生成肉质管,后一组雌、雄蕊高度合生,果通常1室发育,中轴退化。晚第三纪以来,古气候的变迂和亚洲山体的隆升,山茶组 Sect.Camellia,油茶组Sect.Paracamellia以及连蕊茶组 Sect.Theopsis在新的环境中产生进一步分化和自然杂交,出现了一些多倍体种群,细胞地理学研究表明,自中南半岛向北呈现出核型由对称到极不对称、染色体从二倍体到多倍体的变异系列,从而对山茶属中演化与分布的一致性提供了证据。 相似文献
82.
83.
胡启明 《热带亚热带植物学报》1996,4(3):15-17
本文对过去一直认为是日本特有的两种珍珠菜属植物作了归并和组合:将Lysimachia,tashiroiMakino归并作L.patungensisHand.-Mazz.的异名,将L.tanakaeMaxim.降级作L.christinaeHance的亚种处理.对此间植物在中国和日本的地理替代现象作了讨论. 相似文献
84.
在观察大量标本和野外考察的基础上,认为Nannoglottis souliei (Franch.)Ling et Y.L. Chen应作为N.gynura (C.Winkl.)Ling et Y.L. Chen的异名。 相似文献
85.
岩生珠子木(Phyllanthodendron petraeum P.T.Li)和圆叶珠子木(P.orbicularifolium P.T.Li)均为中国广西壮族自治区特有种,二者曾被认为基于叶片质地与形状、叶脉特征、花盘腺体形状以及花柱开裂程度等一系列形态特征可进行区分,然而基于近年来查阅大量标本和野外考察工作认为二... 相似文献
86.
We have investigated and further characterized, in the rabbit retina, the synaptic connectivity of the ON-type cone bipolar cells that are immunoreactive for an antibody against the neurokinin-1 receptor (NK1R). NK1R-immunoreactive bipolar cell axons terminate in stratum 4 of the inner plexiform layer. The axons of NK1R-positive bipolar cells receive synaptic inputs from amacrine cells through conventional synapses and from putative AII amacrine cells via gap junctions. The major outputs from NK1R-positive bipolar cells make contacts with amacrine cell processes. The most frequent postsynaptic dyads comprise two amacrine cell processes. Double-labeling experiments with antibodies against NK1R and either calretinin or glycine have demonstrated that NK1R-immunoreactive bipolar cells form gap junctions with AII amacrine cells. Thus, NK1R-positive cone bipolar cells, together with calbindin-positive cone bipolar cells, may play an important role in transferring rod signals to the ON-type ganglion cells of the cone pathway in the rabbit retina.I.-B. Kim and M.R. Park contributed equally to this work.This work was supported by the Ministry of Science and Technology of Korea (grant no. M1-0108-00-0059; Neurobiology Support Grant). 相似文献
87.
描述了中国广西石灰岩地区苦苣苔科(Gesneriaceae)1新种--鹿寨唇柱苣苔(Chirita luzhaiensis Yah Lin,Y.S.Huang & W.B.Xu).该种与桂林唇柱苣苔(Chirita gueilinensis W.T.Wang)相似,但叶面被长柔毛和短柔毛,花药无毛,花丝近基部膝状弯曲,退化雄蕊3枚,无毛,花期12月至次年1月可与后者区别.目前,鹿寨唇柱苣苔仅见于广西鹿寨县中渡镇的两个石灰岩山洞中. 相似文献
88.
Abstract Results are presented on vascular species richness in three representative alpine plant communities at 1040–1410 m on Mt Burns in the perhumid Fiordland region, a hotspot of alpine plant diversity, in south‐western South Island, New Zealand. Overall species richness was not dissimilar between the three communities in any of the eight plot sizes (mean values of 20.8–24.4 species in the largest plots of 100 m2), even though coefficients of floristic similarity were small (17.9; 23.5) between both low‐alpine communities (snow tussock‐shrubland and snow tussock grassland) and the high‐alpine cushion fellfield. Vascular species richness was generally similar to that in the few other oceanic New Zealand alpine communities for which data are available. The decline in richness from the low‐alpine to high‐alpine zones, revealed in more comprehensive records from two other regions with generally similar oceanic environments, was not recorded, indeed was reversed, on Mt Burns. Whether the recognized biodiversity hotspot of Fiordland has a generally richer high‐alpine flora than other regions in New Zealand needs further examination. The general pattern of alpine floristic richness in relation to elevation, in New Zealand, also prevails in most alpine regions abroad, usually under much more extreme continental environments. This pattern is usually ascribed to the associated decrease in temperature. Both the small size of the land mass and/or associated environmental conditions may be implicated but clarification awaits further data, preferably collected with standardized procedures. 相似文献
89.
We describe a new species of the pseudoxyrhophiine snake genus Thamnosophis from a dry forest of the karstic massif Tsingy de Bemaraha in central western Madagascar. Thamnosophis mavotenda sp. n. is characterised by 19 dorsal scale rows, 188 ventrals, 110 subcaudals, and by colouration (e.g. yellow head sides). Morphological and molecular phylogenetic data indicate that the species is most closely related to the recently described Thamnosophis martae from the far north of the island which inhabits dry karstic forest and subhumid lowland rainforest. This species pair represents a well-supported example of a sister-group relationship in snakes between northern Madagascar and the Tsingy de Bemaraha plateau, and corroborates preliminary observations in other reptile species. We discuss this finding in the light of recent hypotheses on the biogeographic zonation of Madagascar. 相似文献
90.
The purpose of this project was to determine if the detection of pinworm infections in owl monkeys (Aotus nancymae) could be improved by performing perianal tape testing at specific times of the day and/or by performing repeated sampling. Eight Aotus known to be infected with pinworms were sampled at four selected time points (06:00, 12:00, 18:00 and 24:00 hours) over the course of a 3-week period. Samples were examined microscopically and oxyurid eggs were quantified. Results revealed no significant differences in time points, but did indicate that repeated sampling significantly improved pinworm egg detection. Results also determined that Aotus housed with an infected cage mate are at an approximately 14-times greater risk of being infected than animals housed without an infected cage mate. Lastly, results indicated no significant difference between peripheral eosinophil and basophil numbers from infected and clean animals. 相似文献