桃花水母

介绍了桃花水母的生活习性、形态、生理、分类、分布,讨论了桃花水母的研究意义及经济价值。     

桃花水母

桃花水母是水螅纲有世代交替的一类淡水生活的刺胞动物。由于我国的秭归桃花水母的生境在三峡水库蓄水后将被淹没,它的生存受到各方的关注。近期媒体也做了较多的报道,为有利于读者了解这一方面的知识,介绍了桃花水母的螅状体和水母体的形态和生活习性,以及世代交替的情况,提出了有关对桃花水母的研究和保护的一些看法。     

桃花水母是广泛分布物种

由中国科学院水生生物研究所承担、秭归县环保局和北京市水产研究所参加、国务院三峡工程建设委员会办公室资助的“秭归县桃花水母抢救性保护研究”课题于近日在武汉通过验收。在三峡水库蓄水前,原湖北省秭归县归州镇附近位于长江边的3个水潭——天音潭、卧牛潭和鸭子潭的桃花水母的种类     

中国桃花水母属的修订（淡水水母目，笑水母科）

作者对我国的桃花水母属Craspedacusta的2亚种和2变种重新通过形态学观察,并与国内外已发表的Craspeda-custa属7种相比较,其刺丝囊疣的形状和排列及生殖腺的形状和颜色均存在明显的差异。故认为此2亚种和2变种应提升为种,即信阳桃花水母Craspedacusta xinyangensis He,1980,杭州桃花水母Craspedacusta hangzhouensis He,1980、乐山桃花水母Craspedacusta kiatingi Gaw and Kung,1939和宜昌桃花水母Craspedacusta kawaii(Oka,1907)。本文将全世界11种桃花水母的形态特征作了比较并附以系统检索。     

我国桃花水母分布近况

桃花水母是世界的珍稀动物,它具有重要的学术价值和观赏价值.1880年首次在英国发现,订名为索氏桃花水母Craspedacusta sowerbyi Lankester 1880.1880～1939年共发现5种,1980年以后相继报道了6种.1959年台湾省台北市台湾师范大学校园一人工水池中发现桃花水母,共采得4个标本,作者订为一新种C. koui Shieh and Wang 1959.Kramp(1961)认为此非新种,乃为C.sowerbyi,这有待证实.作者在其论文中只称刺丝囊成丛,没描述刺丝囊疣的形状,对生殖腺的形状描述不清,未说明其颜色.为此,台湾的桃花水母难以鉴定.至于前苏联报道的一新种C.vovasi Naumov and Stepanjants 1971,共得16个标本,采自南Sakhalin的Bousset咸水湖.我们认为这不是淡水水母,应是一种海产的水螅水母.Stepanjants于1988年宣告此种无效,他认为此标本是Eperetmus typus Biglow 1915的一个新变种E.typus var.vovasi.因此,目前世界上桃花水母已记录11种,9种分布在我国.     

我国的桃花水母

2003年7月9日至10月16日于浙江省宁波市鄞州和象山分别采得多个桃花水母标本,经鉴定这两种桃花水母为信阳桃花水母。鉴于这几年,我国许多地方相继报道发现有桃花水母出没,在此基础上,参阅了我国在研究桃花水母方面的相关资料,介绍了目前我国关于桃花水母的研究现状, 并指出其研究价值所在,以期为今后桃花水母的研究提供参考依据。     

桃花水母生活史的实验观察

记录了中国产信阳桃花水母(Craspedacusta xinyangensis)的生活史及各阶段主要发育特征。25～28℃条件下,卵受精23h后发育成长0.14～0.21mm的圆棍状浮浪幼虫,养殖环境下,浮浪幼虫在水中漂浮3～5d后固定到人工玻璃底质上,3～4d后发育成长度0.3～0.6mm的螅状体。水螅体产生无纤毛的类浮浪幼虫形成新的螅状体。一个螅状体成熟后产生一个水母芽,新释放的幼水母具有16只触手。     

安徽省桃花水母的初步研究

桃花水母属Craspedacusta隶属于刺胞动物门Cnidaria水螅纲Hydrozoa淡水水母目Limnomedusae笠水母科Olindiidae。我国的桃花水母种类丰富,分布广泛,近年来多地有新种和分布新纪录的报道。安徽曾发现桃花水母,但均未进行详细描述和研究。本文对采自安徽省金寨县梅河河谷水潭内的桃花水母进行了初步研究,依据其伞形、缘膜宽度、触手及平衡囊数目、刺丝囊疣形状和排列方式、生殖腺形状和颜色等形态特征对其进行初步的分类鉴定。结果表明,此次在金寨县发现的桃花水母更接近于宜昌桃花水母Craspedacusta kawaii Oka,1907。这是对安徽省发现的桃花水母首次进行较为明确的分类鉴定和初步的形态学研究。     

秭归桃花水母( Craspedacusta ziguiensis )

\"春来桃花水,中有桃花鱼.浅白深红画不如,是花是鱼两不知\".这首古诗中描述的比画还要美丽的\"桃花鱼\",实际上就是我们今天说的桃花水母.虽然早在1250年,我国对桃花水母及其生活习性就有详细的描述,但按照现代生物学概念命名的桃花水母却是在1880年. 由于这一类群有着数亿年的生存历史,是进化过程中的关键物种,桃花水母被认为有重要的保护价值.     

中国桃花水母属的修订(淡水水母目,笠水母科)

作者对我国的桃花水母属Craspedacusta的2亚种和2变种重新通过形态学观察,并与国内外已发表的Craspeda-custa属7种相比较,其刺丝囊疣的形状和排列及生殖腺的形状和颜色均存在明显的差异.故认为此2亚种和2变种应提升为种,即信阳桃花水母Craspedacusta xinyangensis He,1980,杭州桃花水母Craspedacusta hangzhouensis He,1980、乐山桃花水母Craspedacusta kiatingi Gaw and Kung,1939和宜昌桃花水母Craspedacusta kawaii(Oka,1907).本文将全世界11种桃花水母的形态特征作了比较并附以系统检索.     

Global diversity of inland water cnidarians

Global diversity of inland water cnidarians is low, containing <40 species belonging to phylogenetically distinct groups representing independent invasion events: the common and cosmopolitan hydras (12–15 species); the sporadically occurring freshwater medusae (6–16 sp.); the Cordylophorinae (2 sp.); the parasitic Polypodium (1 sp.); the medusae occurring in saline lakes (4 sp.). Freshwater cnidarians inhabit nearly all types of freshwater on all continents (except Antarctica), but only a few species have cosmopolitan distributions. Due to uncertainty in species knowledge, fine scale regions of endemicity are not yet clear. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

The species in primatology

Biologists of the late eighteenth and early nineteenth centuries all bandied about the term “species,” but very rarely actually said what they meant by it. Often, however, one can get inside their thinking by piecing together some of their remarks. One of the most nearly explicit‐appropriately, for the man who wrote a book called The Origin of Species – was Charles Darwin 1 : “Practically, when a naturalist can unite two forms together by others having intermediate characters, he treats the one as a variety of the other… He later translated this into evolutionary terms: “Hereafter, we shall be compelled to acknowledge that the only distinction between species and well‐marked varieties is, that the latter are known, or believed, to be connected at the present day by intermediate gradations, whereas species were formerly thus connected”^1:484‐5     

Review and analysis of the surveys for natural enemies of Mimosa pigra: What does it tell us about surveys for broadly distributed hosts?

Mimosa pigra L. (Mimosaceae), a serious weed in Australia and Asia, has been the target of a biological control project for 25 years. This woody legume occurs naturally in all tropical American countries from Mexico to Argentina and on many Caribbean islands. In this paper, we analysed the results of surveys for natural enemies of M. pigra conducted in seven countries by several different collectors and which revealed 420 species of insects and five of fungi. We assessed the survey effort relative to the natural distribution of the host-plant to show that large areas of the natural distribution were not covered. We examined the known distribution of the natural enemies to show that most natural enemies occur over the majority of the range of the host, although the Isthmus of Panama is a barrier to many species. This indicates that few potential agents were missed. We show species accumulation curves for three sites to estimate the number of visits required to find most species at a site. Although the species accumulation curves continued to rise, even after 28 collections and 101 insects found at one site, the species utilised for biological control were found relatively early. We expect that these general conclusions (that those insects with potential for biological control are widely distributed and relatively quickly discovered) are applicable to biological control surveys of any target that occurs continuously over a wide geographic range, but possibly not to targets that occupy disjunct distributions.     

The role of a native tussock grass (Paspalum quadrifarium Lam.) in structuring plant communities in the Flooding Pampa grasslands, Argentina

The patches of Paspalum quadrifarium-dominated grasslands found atpresent could be remnants of the vegetation that defined the Pampas landscape inthe past. The mere presence of such physical structures should lead to systemsin which many other species are dependent upon both the autogenic creation ofsurface area for living space and the autogenic and allogenic modulation ofresources controlled by these structures. We carried out amensurative–comparative study in naturally occurring sites dominated byP. quadrifarium that occupy different positions within thelandscape in the Flooding Pampa. We found different species assemblages in thesestructurally homogeneous stands, related to the edaphic and topographicgradients. The comparison with sites from similar positions in the landscapewhere this native tussock-grass was absent showed that the dominance ofP. quadrifarium is a minor determinant of floristicdifferences, which are mainly controlled by abiotic factors. We assigned thesedominated grassland stands to previously delimited vegetation units for theFlooding Pampa grasslands and we compared them with the vegetation unitsassigned, in terms of composite properties of the community that may beindicators of ecosystem processes, such as biological invasions andproductivity. Our results show that this native tussock grass is associated withhigher floristic richness, higher representation of perennials and grasses andlower presence of alien plants. This homogeneous pattern of variation across thevegetation units would suggest that, despite the absence of dramatic changes incommunity composition, the dominance of this tussock grass plays an importantrole in structuring species diversity patterns.     

Forest biodiversity gradients and the human impact in Annapurna Conservation Area, Nepal

Patterns of biodiversity, environment and human impact were studied in 57 sample plots in an 1,178 ha forest area in a rural mountain area of Nepal that is administrated by the Annapurna Conservation Area Project. Alpha-, beta- and gamma-diversity was measured or estimated for six groups of organisms: trees, shrubs, climbers, herbs, polypores and mycorrhizal fungi, and the recorded patterns were correlated with a set of environmental variables. Human impact in terms of fuelwood collection, selective cutting and grazing was found to influence species diversity patterns in all organism groups. Species richness of trees, climbers and polypores at plot level (alpha-diversity) generally responded negatively to human impact, whereas species richness of herbs and shrubs showed a positive relation. Species turnover (beta-diversity), measured as length of the DCA first axis, was significantly correlated to distance to village for all species groups. This indicates that the human impact is very important for the biodiversity patterns in the study area, and that biodiversity connected to undisturbed forest habitats are potentially threatened in the area. The results are discussed in the context of practical conservation. A proposal for future management zones addressing protection of biodiversity without limiting the local use of the forest resource is put forward.     

濒危植物香籽含笑的保护与利用研究

本文对香籽含笑的生态学、生物学特性、迁地保护技术进行了研究,并论述了其在药用、食用香料、木材和园林观赏方面的开发利用价值.在西双版纳地区,香籽含笑树高年平均增长1.1 m,胸径年均加粗1.22 cm;生长期为5～11月中旬,其中6～9月为生长高峰期,花期为11月下旬至翌年2月中旬,果熟期为10月～12月下旬;种子随采随播或贮藏于湿沙中催芽,新鲜种子发芽率为86%;可通过种子和嫁接繁殖.香籽含笑作为傣药原料、天然调香原料具有较好的开发利用前景.     

Gene Flow Happens

Debate over what is a species was already considered old hat when Darwin wrote his seminal abstract (as he called it) more than 150 years ago.¹ Endless papers, workshops, and symposia have been presented in an effort to "solve" the species problem. Yet, here we are, at it again. Has there been any progress? I believe that there has been, and that among the many advances enabled by the genomics revolution, progress on species concepts and species recognition is among them. To quote Feder and colleagues,² we are on the brink of a “unified theory of speciation genomics.”     

生物环及其测度

本文将一类生物种群抽象为“生物环”并定义了生物环上的测度,利用这一测度研究了两类生物种群的可测性．     

花溪饮用水源保护区植物多样性特征及区系分析

探究花溪饮用水源保护区内植被物种组成、区系特点及物种多样性的变化规律,对花溪饮用水源地和湿地生态系统的保护具有重要意义。以花溪饮用水源保护区陆生植物群落为对象,从水库为起始点,选取8个样地进行乔木、灌木、草本植物进行样方调查。结果表明,样地内共有被子植物213种,蕨类植物11种,共计224种,隶属于71科154属;植物区系组成分科级和属级,分布区类型多样,科级水平上有11个类型,以热带地理成分占明显优势,世界分布次之;属级水平上有13个类型,以泛热带分布最多,其次是温带分布;α多样性的变化受水分和物种种类及人类活动的影响,存在一定差异,靠近水库的地方,物种丰富度呈现较高水平,也鲜少受其他因素的影响;Sorensen相似性系数表明样地相邻越近植物共有种就越多,但是随样地间的距离增加,相似性系数也存在不规律变化。