青南牧区南部嵩草草甸群落植被构成及种间关联

植物群落构成和植物种间联结,反映植物物种空间上相互关系,对于草地演替动态及稳定性的揭示具有重要理论意义。以青南牧区南部3个嵩草群落为对象,分析了群落生物量构成变化;并基于2×2列联表及植物种多度,采用Ochiai种间关联度指数及Spearman秩相关分析,探讨了不同嵩草群落的植物种间关系及群落演替特征。结果表明:藏嵩草群落的生物量显著高于高山嵩草+异针茅/杂类草群落,群落生物量主要由莎草科植物构成,其占总生物量的45%~80%,而禾草、杂类草和不可食植物则分别约占总生物量的8.1%,15.2%和16.4%;3个嵩草群落内的植物种对一般存在完全关联、绝对关联和完全独立3种关系,藏嵩草群落和高山嵩草+杂类草群落中完全独立的种对较多,为38.1%和40.0%;而高山嵩草+异针茅群落中完全关联种对较多,为36.3%;3个群落中较多植物种对间存在显著联结性,且显著正联结种对数多于显著负联结种对数,同一种对在不同群落中的种间关系不同;各嵩草群落均处于稳定发展阶段。     

Is there need for leaf-galling grape phylloxera control? Presence and distribution of Dactulosphaira vitifoliae in Swiss vineyards

Grape phylloxera (Dactulosphaira vitifoliae, FITCH) was a major pest in Vitis vinifera grape production in the late 19th and early 20th century in Europe. Roots of V. vinifera varieties are susceptible to D. vitifoliae attack whereas the leaves are not affected. The pest has been controlled by using American grapevine varieties as rootstocks. However, in recent years, grape producers have reported higher incidences of leaf galls induced by D. vitifoliae on V. vinifera leaves. Research on the occurrence of D. vitifoliae on grapevine leaves and roots has shown that D. vitifoliae is present in all wine-growing regions of Switzerland. In more than 80% of vineyards claiming to be infested, D. vitifoliae was found on leaves of varieties with interspecific crosses in their parentage. Three locations with leaf-galling individuals on V. vinifera were detected. D. vitifoliae individuals were found emerging from soil potentially associated with the commonly used rootstock varieties, which are assumed to be phylloxera tolerant. As climate change may necessitate the relocation of some viticultural areas to new wine-growing regions, there will be a greater need to control D. vitifoliae on leaves of interspecific crosses and the inspected planting material to limit further spread of the pest.     

亚比棉及其与陆地棉、海岛棉种间杂交种的核型及似近系数聚类分析

为将原产澳洲的棉属野生种比克氏棉(Gossypium bickii)具有的子叶腺体延缓形成基因导入栽培种,将亚洲棉(G.arboreum)与比克氏棉(G.bickii)杂交,并经染色体加倍,获得亚比棉异源四倍体,然后再用异源四倍体与陆地棉(G.hirsutum)、海岛棉(G.barbadense)杂交获得具有[ADG]3个染色体组的三种杂种。本研究以三种杂种与其亲本为材料,对参试材料进行核型分析,并采用核型似近系数聚类分析方法对参试材料进行聚类分析。研究结果表明:亚比棉染色体的相对长度小于亚洲棉和比克氏棉,且变异范围较小,亚比棉的LC/SC值高于亲本亚洲棉和比克氏棉;亚比棉×陆地棉和亚比棉×海岛棉的LC/SC值比任一亲本均高。亚比棉的臂比均值最小,核型最为对称,为1A。核型聚类结果表明,陆地棉和海岛棉的核型似近系数最大为0.995 8,核型进化距离为0.004 2,亲缘关系最近。比克氏棉和亚比棉的核型似近系数最小为0.648 3,核型进化距离为0.433 4,亲缘关系最远。     

银川平原芦苇群落植物种间关系研究

以银川平原芦苇群落作为研究对象,运用野外调查法对芦苇群落进行研究,采用x2检验和Spearman 秩相关分析检验研究银川平原芦苇群落的种间关联性,并对种间关联的结果进行生态分析。结果表明：银川平原芦苇群落主要的植物构成包括20 种18 属14 科。银川平原芦苇群落主要种群种间呈显著或极显著相关的种对数较少,仅占总种对数的47.89%,其中呈显著正相关种对数的只有20.00%,所占比例均较小,负相关及不相关的种对数占总的种对数的80.00%,所占比重较大。按照其分布的环境条件可划分为4 个生态种组,即水生植物种组、湿生植物种组、中生植物种组、中旱生植物种组。     

外来物种琵琶鼠鱼与土著物种黄颡鱼混养的利弊研究

通过对琵琶鼠鱼与黄颡鱼混养利弊关系的研究,探究外来物种与本土物种混养时的利弊关系,为我国对外来物种的引入提供参考。通过实验室饲喂称重法,对琵琶鼠鱼与黄颡鱼的生长和竞争等进行跟踪监测,并应用数据分析系统软件对测量结果进行分析。结果表明,土著鱼种黄颡鱼对新环境的适应性和稳定性要强于琵琶鼠鱼,黄颡鱼的生长与琵琶鼠鱼的存在及数量多少的相关性不大,与其自身的密度有一定的关系;黄颡鱼数量增多并没有表现出共同御敌的现象,反而增大了种内竞争,使平均增长率呈现较大的波动性。琵琶鼠鱼的存在对土著鱼种黄颡鱼的影响并非预想的大,但其很强的适应性,在试验后期各组均有表现,出现正增长趋势,不能排除长期适应生活环境后,其竞争性会增强。     

Resistance to the Whitefly Aleurotrachelus socialis (Hemiptera: Aleyrodidae) and SSR Marker Identification in Advanced Populations of the Hybrid Manihot esculenta subsp. Manihot flabellifolia

Genes resistant to Aleurotrachelus socialis were transferred to the F₁ from the interspecific hybrid wild species of Manihot flabellifolia to M. esculenta and two advanced generations of backcrosses (BC₁ and BC₂). We characterized the resistance of A. socialis transferred to BC₂ parents (CW67-160, CW67-130, CW67-44), MTAI-8 (BC₁), resistant (CMB9B-73) and susceptible (CMB9B-104) genotypes from contrasting pools, and resistant (MEcu-72) and susceptible (CMC-40) genotypes. Whitefly demography and biology were evaluated. SSR molecular markers associated with a phenotypic response of plant resistance were detected in segregating populations (BC₂). Results showed that although female survival time was similar on all hosts, the lowest averages of longevity, fecundity and oviposition rate were observed in the resistant control MEcu-72, only being significantly similar to the parent CW67-130. When the BC₁ and BC₂ populations were compared, it was found that A. socialis fecundity was eight times lower on CMB9B-73 progeny than on CW67-130, expressing the highest levels of resistance to the whitefly. Ten genotypes of CMB9A and CMB9B family had the best segregation. A total of 486 microsatellite primers were evaluated using bulked segregant analysis (BSA), 11 showed polymorphism between the contrasting pools and only one showed significant differences between resistant and susceptible individuals. In conclusion, fecundity was the parameter that impacted most on the intrinsic rate of A. socialis population growth.     

海洋食物网结构稳定性及干扰响应研究综述

针对当前全球环境急剧变化的背景,本文归纳了海洋食物网结构复杂性常用的量化指标,梳理了食物网稳定性不同维度的概念并深入探究其与复杂性之间的内在联系。根据海洋生态系统的不同干扰类型,分析了各种类型干扰的发生方式以及食物网在应对干扰时的适应机理,最后总结了海洋生态系统数据获取分析以及食物网构建时有待解决的问题,并指出开展初级生产者与消费者之间的相互作用研究能更利于解析全球变化对海洋食物网结构和功能的影响。     

外来种无瓣海桑种内、种间竞争关系研究

根据海南岛东寨港红树林区调查数据,采用Hegyi单木竞争指数模型研究外来种无瓣海桑(1985年引进)林内的种内、种间竞争关系。结果表明,无瓣海桑种内竞争强度随径阶的增大而增强,但胸径大于20cm后增强速度明显减缓。种间竞争强度排列顺序为:无瓣海桑>海桑>白骨壤>秋茄>红海榄>桐花树。乔木上层种间竞争强度与单株胸径的大小严格服从幂函数关系CI=ADB。同时对无瓣海桑是否造成生态入侵问题进行了讨论,认为目前不会造成生态入侵,但它对今后的生态影响仍需加强监测。     

Forage quality of white clover (Trifolium repens L.) × Caucasian clover (T. ambiguum M. Bieb.) hybrids and their grass companion when grown over three harvest years

Interspecific hybrids between white clover (Trifolium repens L.) and Caucasian clover (Trifolium ambiguum M. Bieb.) have been developed to introgress the rhizomatous growth habit into white clover, to increase persistence and drought tolerance. The forage quality of T. repens, T. ambiguum and the backcross 1 (BC1) and backcross 2 (BC2) hybrids and companion grass, when grown in mixtures with an intermediate perennial ryegrass (Lolium perenne L.) under a cutting‐only management, was measured. In vitro dry‐matter digestibility (DMD), water‐soluble carbohydrate (WSC) and crude protein (CP) concentrations of the legume and grass fractions were measured throughout the growing season over three harvest years. Trifolium repens had a lower WSC but a higher CP concentration than the perennial ryegrass companion in all harvest years and at all cuts. The legume fractions from the BC1 and BC2 hybrid plots had a higher WSC and a lower CP concentration but an in vitro DMD value comparable with white clover throughout the growing season and in each harvest year. The grass fractions from the mixtures with the backcross hybrids had a higher WSC and a lower CP concentration than the grass fraction from the T. repens plots, in all harvest years and throughout the growing season. No difference in in vitro DMD between parental species and backcross hybrids was observed. The implications of these results for the development of these hybrids and animal performance are discussed.     

Midsummer Trophic Overlap Between Guanaco and Sheep in Patagonian Rangelands

Diet overlap estimation among species is important to understand interspecific interactions. Through these interactions, one species may extinguish others through competition or adapt through mechanisms such as resource partitioning. The introduction of domestic herbivores in a native assemblage may introduce competition for resources with wild herbivores. In southern Patagonian steppes, guanaco (Lama guanicoe) populations are increasing after a drastic demise during the past century. This is occurring in protected areas and extensive ranching areas for sheep, and in the latter ranchers have rising concerns regarding competition. In this observational study, we measured diet overlap, food selection and preferences, and niche width for guanaco and sheep to compare use of food resources during the summer season. Feces were analyzed through microhistological technique to determine sheep and guanaco diets. Diets of guanaco and sheep were dominated by tussock grass (Festuca gracillima, sheep > 60%, guanaco > 50%), the most abundant plant species. Although food niche widths, measured through Levin’s Index, were narrow, guanaco presented the broadest niche (P < 0.001). Of the 17 identified plant species present in guanaco and sheep diets, 5 were always selected by both ungulates and 1 was always avoided at the four study sites. Overlap between diets was high (> 0.90), evidencing potential competition. In addition, diet overlap coupled with our results of small variation in use and selectivity of food resources suggest the absence of resource partitioning. Therefore, both species might share resources or coexist, possibly due to high availability or spatial distribution of food resources and guanaco resilience to cope with numerically dominant competition from sheep. These findings offer new insight into the understanding of these species’ interactions. It is also a management challenge to emerging wild and domestic herbivores interactions, as well as livestock production concerns at large.