Is the native deer Mazama gouazoubira threatened by competition for food with the exotic hare Lepus europaeus in the degraded Chaco in Córdoba, Argentina?     

M.B. Kufner  L. Sepúlveda  G. Gavier  L. Madoery  L. Giraudo   《Journal of Arid Environments》2008,72(12):2159-2167

Using microhistological analysis of faeces, we studied the diets of the wild Chacoan Brown brocket deer (Mazama gouazoubira) and the exotic European hare (Lepus europaeus) by comparing plant species frequency in faeces with plant species availability. Research was conducted in the dry southern portion of South American Chaco, in forests subjected to livestock ranching in the north of Córdoba province, Argentina. The diet of the Brown brocket deer was more closely related to forage availability (C=0.82195) than the diet of the European hare (C=0.38565). Dicots comprised 90% of the Brown brocket deer diet and were preferred throughout the year, while gramineous species were consumed in low amount. In the diet of the European hare, gramineous species were frequent (65 to 87%) and preferred in every season but in winter, when dicots were consumed in higher proportions (92%). Differences in feeding habits and in habitat use would allow both herbivores to coexist; however, probable competition for food with the European hare during the dry period, in addition to habitat loss, threatens survival of the Brown brocket deer.  相似文献   

Diet and food resource partitioning in koaro,Galaxias brevipinnis (Günther), and juvenile rainbow trout,Oncorhynchus mykiss (Richardson), in two Taupo streams,New Zealand     

Ian A. Kusabs  Stephen Swales 《新西兰海洋与淡水研究杂志》2013,47(3):317-325

This study examined the diet of sympatric populations of migratory juvenile rainbow trout and landlocked koaro in the Waipehi and Omori Streams, Lake Taupo, New Zealand. In both species, diet was dominated, both numerically and by weight, by aquatic prey: Ephemeroptera, Trichoptera, and Diptera larvae were the most numerous prey items. Adult koaro and juvenile rainbow trout both fed on small koaro. Terrestrial prey items were present in low numbers in the diets of both koaro and juvenile rainbow trout, but were more important in terms of weight. Resource partitioning was weak although koaro consumed more small benthic invertebrates such as chironomid larvae, whereas the diet of rainbow trout contained more Ephemeroptera larvae and terrestrial insects. In the Waipehi Stream, koaro consumed both rainbow trout ova and koaro ova; in Omori Stream, trout ova were important in the diet of juvenile rainbow trout. Since the diets of koaro and juvenile rainbow trout in some Taupo tributaries are similar, populations may co‐exist by temporal and/or spatial partitioning of food resources, whereas trout predation on small koaro may be a limiting factor for koaro populations.  相似文献   

Variation of colour patterns in larval Hydropsyche (Trichoptera): Implications for species identifications and the phylogeny of the genus     

Bernhard Statzner  Nathalie Mondy 《Limnologica》2009,39(2):177-183

Larvae of the lotic caddisfly genus Hydropsyche may occur in densities of thousands to several tens of thousands of individuals/m² across continents and running water types. Therefore, stream ecologists frequently face the task of identifying larvae of this genus. Early keys to larval Hydropsyche of Asia, Europe and North America often used the relatively complicated frontoclypeal colour pattern for species discrimination, whereas equivocal views about the variation of this pattern limited its use in recent keys. Has each species of a given species group a different (although intraspecifically variable) basic pattern of lighter spots on the darker frontoclypeus, or have all species of a group the same basic colour pattern that varies more or less intraspecifically? An answer to this question has obvious implications for the identification of the species as well as for the phylogeny of the genus, so we examined the variation of this colour pattern across ∼11,000 specimens of 10 Hydropsyche species from the Loire River (France).All 10 species had the same basic colour pattern on the frontoclypeus (six contrasting light patches on a dark background) that varied intraspecifically across a certain range of colour contrasts. Comparing other sources illustrating the frontoclypeus of Hydropsyche larvae provided more support for the idea that six contrasting light patches on the frontoclypeus is the typical basic colour pattern that varies within almost all European species; males of these species have a simple phallus form. Two European and many North American species of the genus (from the Ceratopsyche group) have a different basic colour pattern of seven light patches on the frontoclypeus that varies also intraspecifically; males of these species have a complicated phallus form.If the variation of such colour patterns in co-existing populations of several species is known, the relative contrast differences among the individual patches on the frontoclypeus and the form of the individual patches can provide valuable information for rapid species identification. Analysis of this variation may also contribute to phylogenetic studies of the genus Hydropsyche and other hydropsychids.  相似文献   

里海地区能源安全及西方对该地区的地缘政治战略   总被引：1，自引：0，他引：1  

高淑琴  唐洪钊 《世界地理研究》2009,18(4):66-73,29

里海地处欧亚大陆的接合处,地理位置极其重要。近年来,随着一批新的里海大型油汽田的探明,里海的石油地位也迅速上升,再次成为世界关注的焦点。苏联解体后,里海地区一方面因其丰富的油气资源储备备受国际社会关注;另一方面,里海面临着激烈的国际竞争局面和不稳定的区域发展前景。本文论述了里海地区油气资源的储备和生产、出口现状以及国际竞争的局面,尤其是西方参与里海地区油气资源竞争的格局,这不仅引起该地区非国家主体的地缘政治的改变,从而也深刻影响着西方国家主体对该地区的战略和政策。  相似文献   

4种典型荒漠植物相互关系     

袁建立  郑凯  王亮 《中国沙漠》2014,34(3):740-746

我们调查了安西荒漠保护区内相邻的4种典型植物珍珠猪毛菜（Salsola passerina ）、合头草（Sympegma regelii ）、红砂（Reaumuria soongorica ）、泡泡刺（Nitraria sphaerocarpa ）个体大小与相对距离,通过对10种组合的个体大小与距离的回归分析,研究其彼此间的相互关系。结果显示：4种植物大小与距离之间是正相互关系,即竞争关系;种内竞争的重要性高于种间竞争的重要性,且竞争物种之间存在不对称性。此结果表明,物种间的这种竞争关系在一定程度上影响了荒漠地区植物群落的构建。  相似文献   

河南经济竞争力的比较研究     

马凌 《地域研究与开发》2005,24(3):20-23

文章在全国比较优势格局中,对河南省的经济发展进行横向和纵向的比较研究:河南省目前虽然在经济总量上具有一定的优势,但经济竞争力在全国仍处于相对落后的地位,特别是人均水平始终低于全国的人均水平。根据河南省经济竞争力的变动轨迹,提出了河南省经济竞争力比较优势偏离、非国有经济发展不足、人口众多与人力资源相对不足的矛盾等主要影响因素。  相似文献   

中原城市群竞合关系及一体化战略研究   总被引：11，自引：3，他引：8  

冯德显  乔旭宁  贾晶 《地域研究与开发》2005,24(6):11-17

文章探讨了中原城市群发展的关键问题及一体化中的竞合关系,以此为出发点,着重研究了郑洛工业走廊、郑汴一体化和郑州跨黄河发展等问题,提出了实现中原城市群一体化的战略措施和对策。  相似文献   

地区旅游业应对外部竞争环境的策略组合     

唐继刚  杨达源  董杰  舒肖明  周彬 《地理与地理信息科学》2005,21(2):102-104,F003

该文总结了旅游地空间竞争的层次、形式与影响因素。以其为理论基础,提出地区旅游业可从3方面积极应对外部竞争环境,即合理确定旅游资源开发价值与开发方向、与相邻地区旅游协作和提高地区旅游竞争力,并针对每方面提出了具体的策略和建议。以与天柱山、天堂寨相邻的岳西县为例,分析该县内外风景区之间现实和潜在的空间竞争关系,阐述岳西县旅游业需要采取的竞争策略组合。  相似文献   

以持续可居性为核心的经济适用房设计     

黄一如  贺永 《中国勘察设计》2009,(1):22-26

在对低收入家庭的居住现状与居住空间需求的调查研究基础上,结合2008年全国保障性住房设计方案竞赛的回顾与思考,提出社会保障型住宅设计的策略与原则。  相似文献   

富营养水体中沉水植物与浮游藻类相互竞争的研究   总被引：21，自引：6，他引：15  

杨清心 《湖泊科学》1996,8(Z1):17-24

本文就沉水植物与浮游藻类在富营养水体中的相互竞争现象及机制作了初步研究。室内外实验结果表明,二者之间存在着复杂的相互竞争关系。在光资源竞争上,浮游藻类占有相对优势;对水中营养盐的竞争是单向的,沉水植物因可以从底泥中得到营养盐而处于优势地位;当光照和营养盐充足时沉水植物对浮游藻类有明显的生化抑制效应,这种抑制可能通过促进藻类沉降而起作用。二者的互竞争受水深、水温及水中营养盐含量的强烈影响,高水温、高营养盐含量及深水均不利于沉水植物,而助长了浮游藻类的竞争优势。沉水植物群落一旦形成较大的密度,就能对浮游藻类产生强烈的抑制,保持自己的优势地位。因此,沉水植被恢复应从水温和水位均较底的冬季开始,严格控制营养盐输入量是非常重要的。  相似文献