外来生物福寿螺入侵的生态风险及其评价探讨

通过对福寿螺生态风险较全面的分析,认为福寿螺不仅会对水稻产生直接的危害,而且会对水生生态系统的生物多样性和水体环境造成直接和潜在的危害。同时,福寿螺在特定空间和时间内具有种群暴发的风险以及向我国长江以北地区继续迁移与扩散的风险。在此基础上,进一步提出了有关福寿螺入侵的生态风险评估的概念框架。该研究结果可为控制与预防福寿螺的危害发生提供相关科学依据与参考。     

海南自然保护区的陆生和淡水贝类

考察了海南自然保护区的陆生和淡水贝类资源 ,采获陆生贝类标本 2 4种 (包括 1未定种 ) ,隶属于 1纲 9科 19属 ;淡水贝类标本共 16种 ,隶属于 2纲 7科 11属 .区系分析表明 :海南的陆生和淡水贝类区系组成以东洋界种类为主 ,其中热带种类占优势 ;海南的陆生和淡水贝类区系与广东大陆有密切关系 ;海南自然保护区的热带季雨林中 ,随着海拔升高 ,淡水贝类的分布呈减少趋势 ;海南的陆生和淡水贝类的大型种类多 ,人畜寄生虫中间宿主螺多     

Land bridge and long-distance dispersal——Old views, new evidence

The theory of sea-floor spreading and continental drift is one of the most important achievements in the last century with large ramification for biogeography[1]. Similarly, cladistics, which was started in the 1960s, has been widely employed in systemati…     

滨海盐沼植物种子扩散过程对潮流阻断的响应机制

滨海盐沼湿地中,种子扩散模式主要由潮汐作用决定,在潮汐沿高程梯度的运动中形成了种子流。滨海围垦活动可以直接影响到盐沼湿地的潮汐作用,进而造成盐沼湿地中种子扩散模式的变化。本研究对不同高程盐沼湿地的种子流通量进行调查,阐明了潮流干扰下盐沼湿地中植物种子扩散模式的响应机制。本研究发现在潮流驱动下,低位盐沼和中位盐沼的种子将会向海陆两端迁移,低位盐沼上部是重要的种子源区,中位盐沼下部成为了种子汇区。而高位盐沼的围垦活动将会改变盐地碱蓬种子扩散模式。中位盐沼下部的种子扩散模式受到的影响最为严重。围垦活动占据或破坏高位盐沼之后,中位盐沼下部将由种子的汇区变为源区,大量的种子净流出将给该区域盐地碱蓬定植造成潜在威胁。      

Evolution of plant reproduction: From fusion and dispersal to interaction and communication

Based on the existing data concerning the evolution of the sexual reproduction, it is argued that the processes of sex differentiation and interactions play a key role in evolution. From the beginning environment and organism are unified. In a changing dynamic environment life originates and the interaction between life and environment develops from simple to more complex organisms. Sexual reproduction is introduced after the origin of meiosis and is a key process in evolution. The asexual reproduction process prepares to dispersal. Sexual reproduction process adds the genome renewal and the gamete-gamete interaction. Reproduction and dispersal are connected and the process of reproduction has similarities between asexual and sexual reproduction. Unicellular algae develop the physiological and morphological sex differentiation. Sex differentiation is connected with the way of dispersal. The step to multicellular plants introduces cell isolation after meiosis and by the stay on the mother plant within a cell or organ, plant-cell apoplastic interaction originates and by prolonged stay the plant-plant interaction. This stay influences the type of dispersal. A life cycle with alternation of generations and two moments of dispersal permits plants to go on land. In ferns a shift in the moment of sex differentiation to meiospore happens and the stay of the macrospore leads to the seed plants. In water all types of sexual reproduction, interactions and the alternation of generations are prepared and these are used to conquest land. On land the biotic dispersal is realized. The phylogeny of sexual reproduction reveals that the sex differentiation and interaction are the main causes in the evolution of sexual reproduction. Sexual reproduction shows interactions during gamete fusion, between organism and environment and in multicellular plants between organisms. With respect to other types of interaction as in symbiosis or the nutrient chain, interaction is considered as an important action which is based on a persisting cooperation and points to a push during evolution. The push is expressed as communication： the driving force in the evolution. Based on the interactions between organisms and interactions between organisms and the dynamic environment, communication is considered as a driving force leading to the evolution as explained in the development of plant reproduction. Consequences for reproduction, its regulation and the process of evolution are discussed.     

Primitive agriculture in a social amoeba

Agriculture has been a large part of the ecological success of humans. A handful of animals, notably the fungus-growing ants, termites and ambrosia beetles, have advanced agriculture that involves dispersal and seeding of food propagules, cultivation of the crop and sustainable harvesting. More primitive examples, which could be called husbandry because they involve fewer adaptations, include marine snails farming intertidal fungi and damselfish farming algae. Recent work has shown that microorganisms are surprisingly like animals in having sophisticated behaviours such as cooperation, communication and recognition, as well as many kinds of symbiosis. Here we show that the social amoeba Dictyostelium discoideum has a primitive farming symbiosis that includes dispersal and prudent harvesting of the crop. About one-third of wild-collected clones engage in husbandry of bacteria. Instead of consuming all bacteria in their patch, they stop feeding early and incorporate bacteria into their fruiting bodies. They then carry bacteria during spore dispersal and can seed a new food crop, which is a major advantage if edible bacteria are lacking at the new site. However, if they arrive at sites already containing appropriate bacteria, the costs of early feeding cessation are not compensated for, which may account for the dichotomous nature of this farming symbiosis. The striking convergent evolution between bacterial husbandry in social amoebas and fungus farming in social insects makes sense because multigenerational benefits of farming go to already established kin groups.     

贵州部分地区陆生贝类调查研究(腹足纲:前鳃亚纲,肺螺亚纲)

首次系统报道贵州省陆生贝类名录共118种(其中含待定种13个),分隶于18科48属,其中有8新种(有6新种已另文报道),即贵阳弯螺SinoeeneaguiyangensisLuoetChen,1998,水田坝贝喇叭螺Boysidia(Bensonella)shuitianbaensisLuoetChen,1998,贵阳喇叭螺Boysidia(Boysidia)guiyangensisLuoetChen,1998,黄果树喇叭螺Boysidia(Boysidia)huangguoshuensisLuoetChen,2000,天星桥喇叭螺Boysidia(Ban sonella)tianxingqiaoensisLuoetChen,2000,茂兰腹皱螺GastroptychiamaolanensisLuoetChen,2002,茂兰沟螺Dioryxmaolanensissp.nov.(另文报道),茂兰果瓣螺Carychiummaolanensissp.nov.(另文报道)。对其种类组成和分布进行了讨论。     

湖北钉螺(Oncomelania hupensis)对光照的感觉反应

设置不同光强、光质、光色3种光刺激环境,观察湖北钉螺在所设环境下的趋避和体位反应.结果表明,湖北钉螺对光强刺激反应明显,当白炽灯光强达到1 050lx、节能灯达到605lx时,钉螺表现出明显的远避行为;而且钉螺对2种不同光质的光源反应表现出明显差异:对节能灯光刺激反应比白炽灯强烈.钉螺对所试的4种光色的反应无明显差别.光位实验结果表现为在强光下钉螺是足背迎光,在有色散射光下钉螺是足底迎光.因此,钉螺对光强和光质有明显的趋避和体位反应,对光色无明显的差异反应.     

天南星中草酸钙的形态及其对钉螺作用的研究

用天南星中草酸钙针晶处理钉螺,并用扫描电镜技术检测钉螺表面损伤情况,结果表明:24 h时,5、2.51、g/L的草酸钙针晶的钉螺致死率为63.33%,10%,0;72 h时5 g/L的草酸钙针晶对钉螺致死作用已接近100%.经过草酸钙针晶对钉螺活动影响实验和扫描电镜检测,可以看出发现草酸钙针晶对钉螺的活动具有抑制作用,可以将草酸钙针晶作为一种有效的灭螺辅助药剂.     

福建省同安县残存钉螺回升及个体变小的原因探讨

1993年即距未次查到钉螺并加以消灭后的第15年,在福建省同安县原钉螺孳生地发现一处4650m~2山坑螺区。钉螺分布的范围、密度已恢复到原始状态。发育成熟的钉螺个体明显变小,经测量:螺层数为4.65(3—5);螺壳长与宽分别为4.76(3.7—5.8)mm和2.27(2.1—2.6)mm,明显小于60—70年代螺和1993年同期捕捉于福建省福清市的同种钉螺。调查结果说明,残存钉螺回升在福建省山丘地区仅需15年左右。钉螺个体明显变小的主要原因可能系短时间内大量繁殖、营养不足、近亲交配、幼龄生育等;次要原因系山地开发、水土冲刷、孳生地贫瘠。     

食物对湖北钉螺(Oncomelania hupensis)发育繁殖的影响

用浮游植物(A)、鲫鱼(B)、河蚌(C)、蚯蚓(D)及以浮游植物与3种动物分别混合组成(E、F、G)的7种饲料喂养钉螺,观察其幼螺成活、生长及雌螺产卵量.结果表明,饲料G喂养的钉螺幼螺成活率(43%)明显高于其他饲料(0~33.3%,),B和C喂养钉螺,其幼螺在一个月内全部死亡;在25℃的条件下,饲料A和G喂养的幼螺发育最快,105d其体长分别为6.89mm和6.81mm,且显著长于(P<0.05)饲料D、E、F喂养的钉螺(其体长分别为3.05mm、4.51mm、5.11mm).在25℃的温度条件下饲料A饲养的钉螺产卵时间长、产卵量高(13.9%),与混合型饲料G喂养的钉螺产卵量(14.1%)相当,而明显高于(P<0.05)饲料D、E、F喂养的钉螺(分别为2.9%、10.1%、11.0%);动物型饲料B和C产卵时间短、产卵量最低(不到2%).因此,植物饲料A和混合饲料G适宜于喂养钉螺.     

高山薄壳田螺的引种试验

于2010年3月选用浙江省庆元县合湖乡高山薄壳田螺15 kg,引种放养在杭州市余杭区仁和镇,经18个月养殖,测量其基本性状。与合湖乡田螺相比,其壳质变厚明显,繁殖能力有所增强,生长速度较快,但幼螺死亡明显增多,产量不高。因此认为,高山薄壳田螺是高山地区特殊的地理位置及气候条件形成的,并不适合引种到平原地区。     

性比,饲料和密度因子对福寿螺产量的影响

用正交试验法研究了性比、饲料和投放密度三因子对福寿螺产量的影响。结果表明,以饲养雌螺、投喂混合饲料(满江红或紫贝浮萍加麸)和每亩投放10万幼螺的组合最好。还讨论了水生植物作为福寿螺饲料的优点和实现福寿螺单性生产的问题。     

微囊藻毒素对澳洲水泡螺的毒性效应

用梯度浓度的微囊藻毒素(6.7μg/L、26.7μg/L、66.7μg/L、166.7μg/L、333.8μg/L、1 335.2μg/L)和人工培养的有毒铜绿微囊藻(Microcystis aeruginosa7806)对澳洲水泡螺(Bulinus australinanus)分别进行急性和亚慢性毒性暴露,观察对螺的毒性效应.急性毒性实验结果表明,澳洲水泡螺对微囊藻毒素有很强的耐受力,试验期间(5 d)未发现螺中毒死亡情况,甚至当微囊藻毒素高达1 335.2μg/L时,仍无死亡.亚慢性口服毒性实验结果发现,澳洲水泡螺可以取食微囊藻,但不能消化;微囊藻严重影响螺生长、繁殖等生理活动,微囊藻的长期喂食暴露会使螺因饥饿或染病而死亡.     

6种淡水腹足类足肌蛋白质的比较研究

以隶属于软体动物门、腹足纲、中腹足目、Jiao蚴科的大沼螺、纹沼螺、长度涵螺、光滑狭口蚴为研究对象，以田螺科的梨形环棱螺、黑螺科方格短沟蜷作为对照，用凝胶电泳方法对上述动物进行了足肌蛋白质的比较研究。结果显示腹足类的足肌蛋白质不但具有种内稳定、种间差异显著的特性，而且电泳谱带的差异程度能够反映出物种的遗传特性和相互的亲缘关系。其中以主要区带的数量、Rm值含量最为明显。通过数值聚类分析后显示，大沼螺、纹沼螺、长角涵螺之间的亲缘关系较近，而光滑狭口螺与上述3个种的亲缘关系较远，其分类地位与梨形环棱螺和方格短沟蜷类似。实验结果与修订后的中腹足目科级分类方案相当吻合。     

槭树属常见树种翅果性状多样性与风传播特征分析

【目的】研究15种槭树属树种翅果性状,探究果实性状和风传播特征之间的相关性,为深入研究槭树属植物果实的风传播机制和种群扩张提供理论参考。【方法】以15种槭树属树种翅果为材料,在分析种子长度、种子宽度、果翅长度、果翅宽度、种子长宽比和种子长/果翅长特征等参数的基础上,模拟果实的传播特征(沉降速度和水平传播距离),比较15种果实性状和风传播特性间的相关性。【结果】①15种槭树属树种翅果开张角度对沉降速度和水平传播距离的影响最大,种子宽度影响较弱;②15种槭树属树种翅果沉降速度为69.14~224.06 cm/s,扇叶槭最慢,梣叶槭最快;扇叶槭果实的水平传播距离最远,梣叶槭最近;③15种槭树属植物果实沉降速度与种子长度、果翅长度、果翅宽度、种子长宽比和种子长/果翅长正相关,与果实两翅开张角度和种子宽度负相关;水平传播距离与果实两翅开张角度、种子长、果翅长、果翅宽、种子长宽比和种子长/果翅长均呈负相关,而与种子宽度正相关,果实水平传播距离与其沉降速度呈负相关,果实沉降速度和水平传播距离受多种性状影响;④对15种槭树翅果的8个性状主成分分析表明,前3个主成分的累计贡献率达82.911%, 基于8个性状进行聚类分析可知,当欧氏距离为10时,15种槭树可分为4类。【结论】果实形态特征的相关性分析表明,15种槭树果实形态特征对沉降速度的影响依次为:两翅张开角度>种子长/果翅长>种子长度>果翅长度>种子长宽比>果翅宽度>种子宽度。果实的水平传播距离受多种因子的综合制约。千粒质量、两翅张开角度、种子长/果翅长可作为槭树分类的重要依据。     

Diet control on carbon isotopic composition of land snail shell carbonate

Carbon isotope compositions for both the carbonate shells and soft bodies (organic tissue) of living land snails collected mostly from the Loess Plateau, China have been measured. The result shows that δ 13C values range from -13.1‰ to -4.3‰ for the aragonite shell samples and from -26.8‰ to -18.0‰ for the soft body samples. Although the shells are enriched in 13C relative to the bodies averagely by 14.2(±0.8)‰, the shell δ 13Ca values are closely correlated to the body δ 13Corg values, expressed as δ 13Ca = 1.021 δ 13Corg 14.38 (R = 0.965; N = 31). This relationship indicates that δ 13Ca is primarily a function of the isotopic composition of the snail diets since previous studies have proved that the snail body is the same as their food in carbon isotope composition. In other words, carbon isotope compo-sition of the carbonate shell can be used as a proxy to estimate the dietary 13C abundance of the land snails. The data also support that the 13C enrichment of the carbonate shells results mainly from the equilibrium fractionations between the metabolic CO2, HCO3-in the hemolymph and shell aragonite, and partially from kinetic fractionations when snail shells form during their activity.     

Parents suppress reproduction and stimulate dispersal in opposite-sex juvenile white-footed mice.

Juvenile dispersal is sex-biased in many mammals and birds: one sex often disperses more often or farther than the other. Two hypotheses are generally presented for sex-biased dispersal. The first holds that juvenile dispersal reduces reproductive and/or resource competition between parents and same-sexed offspring. If so, presence of a parent on the natal home range should both promote dispersal of same-sex offspring and suppress reproduction of those that remain. The second is that juvenile dispersal reduces matings between parents and offspring, thus decreasing the likelihood of inbreeding depression. If so, presence of a parent should favour dispersal and reproductive suppression of offspring of the opposite sex. Here I present evidence that juvenile dispersal in white-footed mice, Peromyscus leucopus, is due to inbreeding avoidance. When population density was high, experimental removal of one parent delayed dispersal of opposite-sexed offspring and only the presence of the parents of opposite sex suppressed juvenile reproduction.     

Pollen-mediated gene flow in Chinese commercial fields of glufosinate-resistant canola （Brassica napus）

One of the most pressing issues surrounding transgenic oilseed rape cultivation is the potential impact of GM genes entering neighboring non-GM oilseed rape plants, related weeds or closely related wild relatives. Following the principle of a case-by-case for transgenic crop safety assessment, we designed experiments to study pollen-mediated gene flow from herbicide-resistant transgenic oilseed rape to Chinese commercial varieties. The pollen dispersal was detected as the progeny of recipient plants that were identified as glufosinate resistant. The results indicated that pollen dispersal occurred up to 2000 m and its rate sharply decreased as the distance from the pollen source increased. However, the rate of long-distance pollen dispersal from 33 to 2000 m was less than 0.015% and did not present a gradual decrease, indicating the randomization of dispersal and pollination. Most pollen dispersed within a 4.5 m area around the transgenic pollen source plot, with a maximum of 1.19% at the sampling site of 1.4 m. Wind direction significantly affected the direction and the distance of pollen dispersal, resulting in the more and farther dispersal in southwest direction. However, the number of potentially pollinating bees was not correlated with direction and distance from the pollen source plot, suggesting that bee density and distribution would not contribute to the differences in pollen dispersal among different directions. This paper is the first report on research in a large-scale experiment of pollen-mediated gene flow under the China＇s environmental conditions and provided scientific evidence for the effective commercialization of transgenic oilseed rape and its safe management. Our results also provided important data on pollen spatial distribution pattern.     

Larval dispersal potential of the tubeworm Riftia pachyptila at deep-sea hydrothermal vents

Hydrothermal vents are ephemeral because of frequent volcanic and tectonic activities associated with crust formation. Although the larvae of hydrothermal vent fauna can rapidly colonize new vent sites separated by tens to hundreds of kilometres, the mechanisms by which these larvae disperse and recruit are not understood. Here we integrate physiological, developmental and hydrodynamic data to estimate the dispersal potential of larvae of the giant tubeworm Riftia pachyptila. At in situ temperatures and pressures (2 degrees C and 250 atm), we estimate that the metabolic lifespan for a larva of R. pachyptila averages 38 days. In the measured flow regime at a fast-spreading ridge axis (9 degrees 50' N; East Pacific Rise), this lifespan results in potential along-ridge dispersal distances that rarely exceed 100 km. This limited dispersal results not from the physiological performance of the embryos and larvae, but instead from transport limitations imposed by periodic reversals in along-ridge flows and sustained episodes of across-ridge flow. The lifespan presented for these larvae can now be used to predict dispersal under current regimes at other hydrothermal vent sites.