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21.
Mo Fatemi 《Biological conservation》2009,142(7):1461-1468
Wind-facilitated migration of new genotypes into small, geographically disjunct populations should buffer them against local extinction. Bertya ingramii, a monoecious, wind-pollinated shrub, is restricted to three populations in a 4 km2 area in eastern Australia. Populations are separated by deeply dissected gorges where it is unlikely that seeds are exchanged but where wind movement may facilitate pollen dispersal. Using 156 highly polymorphic ISSR markers, we found moderate genetic variation within and among populations of B. ingramii and less genetic diversity in a nearby and small population of the widespread Bertya rosmarinifolia. The smallest population of B. ingramii (<30 plants) had the highest genetic variation (65% polymorphic markers, Shannon Information Index = 0.30). AMOVA and a Bayesian analysis showed that molecular variance was equally distributed within and among populations suggesting that gene flow is as limited within as in among populations. Genetic distances between populations were only weakly explained by their relative geographic distances (mantel test, R2 = 0.21, P = 0.001) but the distribution of private bands, the departure from Hardy-Weinberg equilibrium, and a UPGMA tree showed that the smallest population of B. ingramii was generally more similar to an upstream population of B. rosmarinifolia. Thirty-eight percent of bands in this small population of B. ingramii were exclusively shared with B. rosmarinifolia. This covert hybridisation may have been an ancient event but may be responsible for contemporary declines in germination and establishment in B. ingramii. The conservation implications are amplified by the endangered status of B. ingramii. 相似文献
22.
Aristotelis C. Papageorgiou Reiner Finkeldey Hans H. Hattemer Sotirios Xenopoulos 《European Journal of Forest Research》2005,124(2):119-124
Individuals were selected for resistance against the imperfect fungus Seiridium cardinale Wag in six common cypress populations (Cupressus sempervirens L.) in Greece. A total of 109 resistant clones and 140 trees from their base populations were surveyed at several allozyme loci. The comparison yielded information on changes in genetic variation due to artificial selection. The genetic structure of the breeding populations was similar to their base populations. Nevertheless, the number of rare alleles among the resistant clones had decreased, showing a similar trend at most loci and for most comparisons. Possible implications for breeding strategies are discussed. 相似文献
23.
神农架地区珍衡植物沿河岸带的分布格局 总被引:2,自引:0,他引:2
Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid
their attentions to riparian zone and had been aware of the important effects of riparian zone in basic study and practical
management. In this study, 42 sampling belts (10 m×100m) parallel to the bank of Xiangxi River at different elevations in
Shennongjia Area were selected to investigate the riparian vegetation and rare plants. 14 species of rare plants were found
distributing in riparian zone, accounting for 42.4% of the total rare plant species in Shennongjia Area. The main distribution
range of the 14 rare plant species was the evergreen and deciduous mixed broadleaved forest at elevation of 1200–1800 m, where,
species diversity of plant community was the maximum at the moderate elevation. The analysis of TWINSPAN divided the 14 rare
species into 3 groups against the elevation, namely low elevation species group, moderate elevation species group, and high
elevation species group. The analysis of DCA ordination showed similar results to that of TWINSPAN. In the paper, the authors
discussed the reasons forming the distribution pattern of rare plant species, and pointed out that the important function
of riparian zone on rare plant species protection.
Foundation item: This project was supported by National Natural Science Foundation of China (NSFC39970123), and Changbai Mountain Open Research
Station, Chinese Acadamy of Science.
Biography: JIANG Ming-xi (1965-), male, associate professor in Wuhan Institute of Botany, Chinese Academy of Sciences, Wuhan 430074,
P. R. China
Responsible editor: Chai Ruihai 相似文献
24.
[目的]考察浸矿剂硫酸铵(NH4)2SO4胁迫下稀土离子钇的毒性研究。[方法]选择蚯蚓作为土壤生态环境污染指示生物,采用滤纸接触法研究硫酸铵胁迫下稀土钇( Y)对蚯蚓的急性毒性效应。[结果]①稀土钇单一染毒,蚯蚓的48 h 半致死率浓度为 LC50=213.41 mg/L、24 h半致死率浓度为 LC50=322.63 mg/L。②硫酸铵单一染毒下,蚯蚓的48 h半致死率浓度为 LC50=13.89 g/L、24 h半致死率浓度为LC50=15.05 g/L。③低浓度10 g/L的硫酸铵与稀土钇复合染毒,蚯蚓的48 h半致死率浓度LC50=198.65 g/L、24 h 半致死率浓度 LC50=399.85 g/L;中浓度14 g/L的硫酸铵与稀土钇复合染毒,蚯蚓的48 h半致死率浓度 LC50=167.3 mg/L、24 h半致死率浓度 LC50=256.73 mg/L;高浓度20 g/L的硫酸铵与稀土钇复合染毒,蚯蚓的48 h半致死率浓度 LC50=31.03 mg/L、24 h的LC50=127.65 mg/L。[结论]低浓度的硫酸铵降低稀土钇对蚯蚓的毒性,产生一定的拮抗作用。中浓度的硫酸铵增加稀土钇对蚯蚓的毒性,产生较明显的协同作用。高浓度硫酸铵显著增加了稀土钇对蚯蚓的毒性。稀土钇染毒下蚯蚓死体更易断裂,而活体对针刺反应相对不灵敏。 相似文献
25.
26.
[目的]为了提高化探样品的分析质量和分析速度.[方法]通过1/5万区域地质矿产调查项目,在青海东部地区发现土壤中含有稀土元素.稀土就是化学元素周期表中镧系元素-镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu),以及与镧系的15个元素密切相关的2个元素-钪(Sc)和钇(Y),共17种元素.采用电感耦合等离子体质谱仪(ICP-MS),测试化探样品中的稀土元素.[结果]按照该研究分析方法测定稀土15种元素的结果令人满意.[结论]该方法具有操作简便、准确性良好的特点,适用于区域地球化探样品的分析测试. 相似文献
27.
Rare species have restricted geographic ranges, habitat specialization, and/or small population sizes. Datasets on rare species distribution usually have few observations, limited spatial accuracy and lack of valid absences; conversely they provide comprehensive views of species distributions allowing to realistically capture most of their realized environmental niche. Rare species are the most in need of predictive distribution modelling but also the most difficult to model. We refer to this contrast as the “rare species modelling paradox” and propose as a solution developing modelling approaches that deal with a sufficiently large set of predictors, ensuring that statistical models are not over-fitted. Our novel approach fulfils this condition by fitting a large number of bivariate models and averaging them with a weighted ensemble approach. We further propose that this ensemble forecasting is conducted within a hierarchic multi-scale framework. We present two ensemble models for a test species, one at regional and one at local scale, each based on the combination of 630 models. In both cases, we obtained excellent spatial projections, unusual when modelling rare species. Model results highlight, from a statistically sound approach, the effects of multiple drivers in a same modelling framework and at two distinct scales. From this added information, regional models can support accurate forecasts of range dynamics under climate change scenarios, whereas local models allow the assessment of isolated or synergistic impacts of changes in multiple predictors. This novel framework provides a baseline for adaptive conservation, management and monitoring of rare species at distinct spatial and temporal scales. 相似文献
28.
29.
文山县泰昌珍稀濒危植物园建设的意义及其可行性 总被引:1,自引:0,他引:1
位于文山县西北部,拟由私营企业文山泰昌花木场承建的文山泰昌珍稀植物固总规模63hm^2。文章论述了植物固建设对开展古老、珍稀、濒危物种种质资源的收集、迁地保存、驯化、繁育栽培以及发展经济等方面的重要意义。谊植物固划分为珍稀濒危植物展示区、繁育试验示范区、森林生态防护区、生活服务区。分析了建因的基本条件及其可行性。 相似文献
30.
通过黑化雉鸡 (Melanisticmuckedpheasant)和大型环颈雉鸡 (Jumboringneckedpheas ant)的正交和反交 ,以及F1 中进行自交 ,观察F1 和F2 中羽色性状的表现和分离比例。试验结果表明 ,黑化雉鸡羽色性状对于环颈雉鸡羽色的遗传方式是显性遗传 ,而且显性是完全的 ;黑化雉鸡羽色性状也由常染色体上一对等位基因M来控制的 ,并不存在显性致死现象 相似文献