Genetic diversity of three endangered species of <Emphasis Type="Italic">Echium</Emphasis> L. (Boraginaceae) endemic to Cape Verde Islands

Echium hypertropicum, E. stenosiphon and E. vulcanorum are the three endemics representative of the genus Echium (Boraginaceae) in Cape Verde archipelago. The aim of this study is to provide a first attempt at estimating genetic diversity among natural populations of these endangered Echium species based on RAPD, so as to provide data available for future appropriate strategies for their conservation. PCO and UPGMA of RAPD analysis suggests a close genetic proximity between the Southern endemic species (E. hypertropicum and E. vulcanorum) and shows that the levels of polymorphism strongly differ between these two Echium species (27 and 29% respectively) and E. stenosiphon (74%), the Northern endemic species. Mantel test also corroborates a close genetic proximity between genetic and geographic data. Population genetic analysis of E. stenosiphon revealed low levels of gene flow between islands (Nm = 0.32) being S. Nicolau the most isolated as evident in PCO. Furthermore the differentiation between groups of individuals belonging to putative subspecies was tested by AMOVA. According to our results there is no genetic basis to consider the two subspecies of E. stenosiphon namely ssp. stenosiphon and ssp. lindbergii. Our results enable us to suggest that E. stenosiphon must be ranked as a Threatened species. Measures aiming at conservation of E. hypertropicum and E. vulcanorum must be implemented at short-term taking into account the small number of existing plants and its low genetic variability.     

Endemism in the Flora of China—Studies on the Endemic Genera

China, under highly varied ecological conditions resulted from wide latitudinal and altitudinal ranges and from the adequate precipitation, has developed a very rich flora of great diversity. As far as flowering plants are concerned, there are 2980 genera, 214 of which, belonging to 64 families, are endemic. Among these endemic genera, there are 9 genera of taxads and conifers, 19 genera of monocots and others of dicots. Of the approximately 129 herbaceous endemic genera in the Chinese flora as a whole, about 22 (17%) are annual and 107 (83%) are biennial or perennial. In the present paper the ecological distribution, the nature of endemic genera and the centers of endemism are discussed. 1. Three types of endemic genera are distinguished, neoendemics, palaeoendemics and active epibiotics, The endemic genera in the flora of China are, for the most part, considered to be very old ones, and most of them are of temperate nature. 2. the degree of endemism in our 22 floristic regions is shown in Figure 1. The areas richest in endemic genera in the Chinese flora as a whole are the 13, 16 and 17 regions. The poorest are the 2, 4, 9 and 10 regions, and no one in the 1 and 3 regions These results on floristic richness are of general applicability. As shown in table 1, the difference in the degree of endemism among the seven Chinese floristic subkingdoms are most pronounced. 101 endemic genera are known to occur in one subkingdom, 72 to occur in two subkingdoms, and 3 to occur in four subkingdoms, only one genus widely distributed in five subkingdoms. However, there is no genus occurring in seven subkingdoms. The difference in the degree of endemism in each subkingdom reveals that the distribution of endemic genera is not well-distributed in the Chinese flora as a whole. Analysis of the vertical distribution of the 200 endemic genera of the Chinese flora bears out that there is no evident increase in endemism as a whole with altitude. 3. Three centers of endemism are found (Fig. 2). These are as follows: a). Eastern Sichuan-western Hubei center. b). Southeastern Yunnan-western Guangxi center. c). Western Sichuan-northwestern Yunnan center. The degree of endemism andcharacters of endemic genera in each center are discussed.     

巨须裂腹鱼年龄与生长的初步研究

巨须裂腹鱼(Schizothorax macropogon)是雅鲁藏布江的重要经济鱼类.作者利用2004～2006年在雅鲁藏布江水系收集的293尾样本,以背鳍条磨片作为主要鉴定年龄的材料,对西藏雅鲁藏布江巨须裂腹鱼种群进行了年龄结构和生长特性的研究.结果表明,巨须裂腹鱼的雅鲁藏布江种群由2～14龄和16龄共14个龄组组成.其中优势龄组为4～6龄(占74.85%).群体总性比为(♀:♂)=1:0.881.体长与体重的关系方程分别为:W♀=0.023L2.904(♀),W♂=0.018L2.962(♂),属于匀速生长类型.用von aertalanffy方程描述的生长方程分别为♀:Lt=65.676[1-e-0.053(t+3.305],Wt=4520.633[1-e-0.053(t+30305)]2.904;♂:Lt=49.622[1-e-0.074(t+4.017)],Wt=2034.481[1-e-0.074(t+4.017)]2.962.雌、雄个体生长的拐点年龄分别为16.6龄和10.7龄,对应的体长及体重分别为43.06 cm、1326.75 g(♀)和32.86 cm、600.31 g(♂).     

Micropropagation from inflorescence stems of the Spanish endemic plant Centaurea paui Loscos ex Willk. (Compositae)

Tissue culture techniques have been established as a useful approach for ex situ conservation of rare, endemic or threatened plant species. This report describes the micropropagation of Centaurea paui Loscos ex Willk (Compositae), an extremely endangered plant species endemic to the Valencia Community (eastern Spain), as a conservation measure which does not cause damage to the wild plants used as explant source. Inflorescence nodal segments of C. paui were selected as explants for in vitro establishment. The best rate of shoot proliferation was obtained on Murashige and Skoog (MS) mineral medium supplemented with 0.5 mg/l 6-benzyladenine or with 2 mg/l kinetin. Maximum shoot elongation was achieved without growth regulators, and the addition of cytokinins significantly decreased their size. In vitro rooting of shoots was difficult after 6 weeks on rooting media. The combination of 2 mg/l indole-3-acetic acid plus 2 mg/l indole-3-butyric acid on MS medium yielded the best results. In this medium, 40% of shoots rooted before 30 days of culture. About 70% of the rooted plants were successfully transferred to pots and acclimatized to ex vitro conditions. Received: 12 January 1998 / Revision received: 10 October 1998 / Accepted: 28 October 1998     

Global dynamics of a SEIR model with varying total population size

A SEIR model for the transmission of an infectious disease that spreads in a population through direct contact of the hosts is studied. The force of infection is of proportionate mixing type. A threshold sigma is identified which determines the outcome of the disease; if sigma < or = 1, the infected fraction of the population disappears so the disease dies out, while of sigma > 1, the infected fraction persists and a unique endemic equilibrium state is shown, under a mild restriction on the parameters, to be globally asymptotically stable in the interior of the feasible region. Two other threshold parameters sigma' and sigma are also identified; they determine the dynamics of the population sizes in the cases when the disease dies out and when it is endemic, respectively.     

Historical processes and environmental factors as determinants of inter-island differences in endemic faunas: the case of the Balearic Islands

Aim We describe current interisland similarities of endemic faunas, and elucidate the significance of historical factors and environmental ones in determining the pattern found. Location The six major islands of the Balearics (Western Mediterranean). Method An extensive review of all the endemic fauna ranging from platyhelminthes to mammals is made. From 568 presumed endemic species and subspecies, 230 full species with neither taxonomic nor distributional uncertainty are chosen. Inter-island similarities are determined using such a presence-absence matrix. Finally, relationships between the matrix of faunistic similarity and a number of matrices measuring environmental and historical factors are elucidated. Results Endemic fauna similarities depend clearly on historical factors. Dependence on environmental factors is unclear. Moreover, endemic fauna reveals two clear-cut clusters of islands within the Balearics: the Gymnesic Islands, in the NE, and the Pityusic Islands in the SW. Historical factors cluster the Balearic Islands in the same way. Contrasting, environmental variables show smoothed, no significant differences among the Gymnesics and the Pityusics. Main conclusions Pre-human flora (palynology) and fauna (bird and mammal fossil record) suggest that environmental differences among the Gymnesics and the Pityusics have now been reduced in comparison to the environmental differences at the Pleistocene and Holocene boundary. This environmental homogenization is likely related with human invasion. Historical effects of prehuman differences between Gymnesic and Pityusic Islands are still recognizable on endemic fauna. In contrast, there is no historical effects on interisland similarities using currently breeding birds (as an example of organisms well-dispersed and related to vegetation type). We explain the pattern of interisland similarities of endemic fauna as the result of the independent histories among the two islands groups. Contrasting, successive colonizations and extinctions would determine interisland similarities of breeding birds.     

湖北西陵峡地区珍稀特有植物分析

湖北西陵峡地区位于湖北西南山地的北部,为了区城上的完整性,作者将临界的巫峡东段也考虑在内,其范围包括宜昌、兴山、秭归、巴东等县的分水岭区域。本文提出峡区存在中国真特有属36属,国家保护植物36种,其它珍贵稀有植物50种,并分析了区系特点,为西陵峡地区植物资源的合理利用和建立峡区自然保护区提供依据。     

广西武鸣县种子植物区系研究

为了解广西武鸣县野生种子植物区系特征, 对其野生种子植物资源进行调查。结果表明,广西武鸣县有野生种子植物2 542种,隶属于184科898属,以被子植物占优势,裸子植物贫乏。从科属组成上看,以大科、单种属和寡种属为主体。科、属和种分布区类型丰富,含典型的热带亚热带成分,兼具温带成分,呈热带至亚热带过渡性质。与邻近地区比较,武鸣县植物多样性比较丰富,植物区系成分与广西横县最相近。因此,武鸣县种子植物多样性丰富、热带性质明显、地理成分多样、起源古老,同时聚集了一些特有植物和珍稀濒危植物,体现出北部湾植物区系的特征。     

雷州半岛15个阔叶树种混交幼林的生长分析*

通过15个阔叶树种2.5a生幼林在雷州半岛的生长比较,结果表明,树高、胸径和冠幅生长超过所有树种平均值的有水翁(Cleistocalyx operculatus)、盘架子(Winchia catophyua)、麻楝(Chukrasia tabularis)和秋枫(Bischofia javanica);按生长过程变化15个树种可分为3个类型:一是水翁、盘架子、秋枫和阴香(Cinnamomum burmanni),二是山楝(Aphanamixis polystachya)、麻楝、樟树(Cinnamomum camphora)、黎蒴栲(Castanopsis fissa)、火力楠(Michelia macdurei)、人面子(Dracontomelon duperreanum)、扁桃(Mangifera persiciformis)和榄仁树(Temninalia catappa),三是见血封喉(Antiaris toxicaria)、木棉(Bombax malabaricum)和无忧树(Saraca dives),不同类型的树种对生态位有不同要求,营造混交林应注意选择搭配。月平均温度、降雨量和相对湿度与多数种类的早期树高生长量与有较好的相关性,而与胸径和冠幅生长量的相关性则不明显。     

Synopsis of the Argentinian scarab genus Pseudogeniates Ohaus (Coleoptera,Scarabaeidae, Rutelinae)

The scarab beetle genus Pseudogeniates Ohaus (Scarabaeidae: Rutelinae: Rutelini) is endemic to Argentina. The genus includes three species: Pseudogeniates cordobaensis Soula, Pseudogeniates intermedius Ohaus, and Pseudogeniates richterianus Ohaus. We characterize the genus, provide a key to species, redescribe and diagnose each species, provide spatial and temporal distributions, and discuss distributions of the species in relation to eco-regions and areas of endemism in Argentina.