捕食风险的种群动态效应及其作用机理研究进展

捕食者不但可以通过直接捕杀猎物而控制猎物的种群数量,还可以通过捕食风险效应影响猎物种群的繁殖和动态,并且在某些情况下,捕食风险效应对猎物种群动态的控制作用甚至大于捕食者的直接捕杀.关于捕食风险效应对猎物动物繁殖产出和种群动态变化的作用及其机理方面的野外研究越来越受到国内外学者重视.本文介绍了近年来捕食风险效应的研究进展,重点关注了美国黄石国家公园中捕食者对马鹿(Cervus elephus)、加拿大育空地区的捕食者对白靴兔(Lepus americanus)的捕食风险效应等案例研究,以阐明捕食风险效应对猎物种群动态影响的重要性,以及关于捕食风险效应影响猎物种群繁殖和动态机理的两个假说(捕食者敏感食物假说、捕食应激假说).并结合我国在捕食者与猎物之间关系的研究现状,提出了进一步在野外开展捕食风险效应对濒危有蹄类猎物种群动态影响研究的建议,阐释了开展这些研究的重要意义.     

稀疏效应下周期系数捕食-被捕食系统的全局渐近稳定性

研究一类稀疏效应下周期系数捕食-被捕食系统,得到了该系统存在唯一全局渐近稳定的正周期解的充分条件．     

稻田主要捕食性天敌的栖境生态位与捕食作用分析

本文进行了稻田捕食性天敌与稻飞虱的栖境生态位调查,并应用正交试验设计、添加试验法和排除试验法研究了?物种的栖境生态位与各天敌捕食作用的关系,结果表明：在5种灭敌与2种害虫共存系统中,天敌对褐飞虱Nilaparvata lugens Stal捕食量的正主效应大小依次为： 粽管巢蛛 Clubiona aponicola、青翅蚁形隐翅虫Paederus fuscipes、前齿肖蛸Tetragnatha praedonia、食虫沟瘤蛛 Ummeliata insecticeps,拟水狼蛛Pirata subpiraticus的负主效应值最大(随狼蛛密度增大捕食量下降);对稻纵卷叶螟Cnaphlocrcis medinalis Guenee捕食量正主效应大小依次为： 粽管巢蛛、肖蛸、青翅蚁形隐翊虫。多物种共存系统中,狼蛛、微蛛、跳蛛主要捕食飞虱;肖蛸主要捕食稻纵卷叶螟;管巢蛛对两种害虫均具有较好的控制作用。这与各物种的生态位宽度值相一致。当飞虱密度在每穴10一30头时,多物种共存系统优良的生物序是拟水狼蛛、食虫瘤胸蛛、青翅蚁形隐翅虫各为l头,棕管巢蛛2头,此时天敌的控制作用最大。添加法和排除法试验结果表明在具-定数量的多物种共存系统中,再增加天敌密度不一定能增加猎物的被捕食数,其直接的生物学原因是种间种内干扰(包括种间种内残杀)     

一类稀疏效应下捕食—被捕食系统极限环的唯一性

捕食与被捕食种群增长可以Lotka-Votterra模型x=ax(1-kx)-bxy y=y(-a+βx)描述,其中a,k,b,a,β皆为非负常数,其生物意义见[1],但是人们在长期的研究     

具有捕食正效应的捕食-食饵系统

在经典的捕食食饵系统中考虑到由于捕食效应对食饵种群带来的正向调节作用后,提出了具有捕食正效应的捕食-食饵系统.通过对模型的动力学行为的分析,从理论上说明了正向调节作用对系统的影响,并就第一象限内平衡点存在时的相图解释了捕食正效应的作用.结果表明:(1)捕食系统中适当的正向调节作用会增加系统的稳定性;(2)当捕食正效应达到一定的程度后系统拥有一个不稳定的极限环;(3)当捕食正效应过大时会使系统的稳定性发生变化,使捕食者种群与食饵种群同时趋向无穷,出现了调节放纵现象.这些结果在保护生物学中具有重要的意义.     

具有比率依赖和密度制约的周期捕食-被捕食系统的一致持久性(英文)

系统的讨论了具有比率依赖和密度制约的周期捕食-被捕食系统的持久性问题,不仅得到了系统一致持久的充分条件,还得到了必要条件,并且持久性条件在模型中得到验证.     

捕食者—猎物功能响应模型研究

本文通过分析在捕食的情况下猎物种群的平均绝对增长速率与捕食效应的关系以及捕食者的捕食平均绝对速率与猎物密度的关系,建立了捕食者-猎物功能响应的一般模型: 其中,A为捕食者与猎物行为常数,f(H_t)为待定函数。 在上述模型的基础上讨论了在捕食速率与猎物密度无关和有关时的功能响应行为。 通过对上面模型的分析,笔者认为功能响应模型按Holling的Ⅰ、Ⅱ、Ⅲ型响应曲线相应划分很不方便。建议按“捕食速率与猎物密度无关或有关”两个类型划分。并认为Ⅲ型模型在昆虫中也能得到较广泛的应用。     

异色瓢虫对与本土蚜虫共存的外来扶桑绵粉蚧的搜寻和捕食行为

[目的]外来入侵物种作为猎物可能影响本土广谱捕食者的搜寻和捕食行为.本研究旨在揭示异色瓢虫Harmonia axyridis对与本土豌豆修尾蚜Megoura japonica混合发生的外来入侵扶桑绵粉蚧Phenacoccus solenopsis的搜寻和捕食行为.[方法]试验前对异色瓢虫设两个饲喂猎物种类处理:用扶桑绵...     

具有Beddington-DeAngelis功能反应函数和密度制约的捕食-被捕食系统的殆周期解（英文）

研究了具有Beddington-DeAngelis功能反应函数和密度制约的捕食-被捕食系统的殆周期解.得到正不变性和持久性的充分条件,还通过构造李雅普诺夫函数得到惟一正殆周期解存在和全局渐近稳定的充分条件.     

黄玛草蛉对木瓜粉蚧的捕食作用评价

为明确黄玛草蛉Mallada basalis(Walker)对木瓜粉蚧Paracoccus marginatus Williams and Granara de Willink的捕食作用,在实验室条件下观察了黄玛草蛉2龄、3龄幼虫对木瓜粉蚧2龄、3龄若虫及成虫的捕食选择偏好,同时采用捕食功能反应方法评价了黄玛草蛉2龄、3龄幼虫对木瓜粉蚧各虫态的捕食效能.结果表明,黄玛草蛉2龄、3龄幼虫偏好捕食木瓜粉蚧若虫,对木瓜粉蚧各虫态的捕食量均随着猎物密度的增加而增加符合HollingⅡ模型.其中,黄玛草蛉3龄幼虫具有较高的捕食能力,其对木瓜粉蚧2龄、3龄若虫及成虫的日最大捕食量分别为116头、81头和19头,a/Th值(a为瞬时攻击率,Th为处置单头猎物时间)分别为284.76、134.26和28.38.黄玛草蛉幼虫对猎物的寻找效应随猎物密度的增加而呈线性下降,且在相同猎物密度条件下,黄玛草蛉3龄幼虫对猎物的搜寻效应明显高于2龄幼虫.研究结果表明,黄玛草蛉对木瓜粉蚧具有较好的捕食能力.     

Influence of predator and dietary chemical cues on the behaviour and shredding efficiency of Gammarus pulex

In two laboratory experiments, we examined short- and long-term responses of the detritivorous amphipod Gammarus pulex to chemical cues from potential predators fed various diets. In the first experiment we studied the short-term effect on G. pulex (locomotory activity) when exposed to chemical cues from three co-existing predators; sculpin (Cottus gobio), trout (Salmo trutta), and signal crayfish (Pacifastacus leniusculus). Chemicals from sculpins and trout induced a short-term decrease in locomotory activity in G. pulex, whereas crayfish did not. There was no difference in activity between G. pulex exposed to water scented by trout or sculpin, and these responses were independent of predator diet (G. pulex, Asellus aquaticus and starved). In the second experiment we examined whether longer-term exposure (4 week) to chemical cues from sculpins affects rates of leaf processing by G. pulex. During the first week, G. pulex consumed significantly more leaves in the control (i.e., no fish cue) than in the fish cue treatment. After 4 weeks, however, there was no difference in total leaf processing rate between treatments indicating an adaptation to the cue.     

Temporal variation in behavioral responses to dietary cues from a gape‐limited predator in tadpole prey: A test of the phylogenetic relatedness hypothesis

The ability of prey to recognize and adequately respond to predators determines their survival. Predator‐borne, post‐digestion dietary cues represent essential information for prey about the identity and the level of risk posed by predators. The phylogenetic relatedness hypothesis posits that prey should respond strongly to dietary cues from closely related heterospecifics but respond weakly to such cues from distantly related prey, following a hierarchical pattern. While such responses have mostly been observed in prey at their first encounter with predators, whether prey maintain such hierarchical levels of investment through time remains unclear. We investigated this question by exposing Rhacophorus arboreus tadpoles to the non‐consumptive effect of gape‐limited newt predators Cynops pyrrhogaster that were fed one of five prey diets across a gradient of phylogenetic relatedness: frog tadpoles (Rhacophorus arboreus, Rhacophorus schlegelii, Pelophylax nigromaculatus, and Hyla japonica) and medaka fish (Oryzias latipes). Predators’ diet, time, and their interaction significantly influenced tadpole activity level. We found support for the phylogenetic relatedness hypothesis: Investments in defense were stronger to cues from tadpole diets than to cues from fish diet. However, such a hierarchical response was recorded only in the first four days following predator exposure, then gradually disappear by day 8 on which the tadpoles exhibited similar activity level across all predator treatments. The findings suggest that, at least under the threat of gape‐limited predators, prey use phylogenetic information to evaluate risk and appropriately invest in defense during early encounters with predators; however, energy requirements may prevent prey from maintaining a high level of defense over long exposure to predation risk.     

火烧信号对种子萌发影响的研究进展

火作为一个基础的生态因子, 对森林、草地等陆地生态系统的结构和功能有着重要的影响。种子萌发是种子植物的重要生活史阶段, 也是火后植被更新和恢复的主要途径。植被燃烧产生了烟、热以及与烟相关的一系列火烧信号, 在打破种子休眠, 促进种子萌发方面发挥重要作用。该文将火烧信号分为物理信号和化学信号, 物理信号主要是伴随火烧产生的高温, 化学信号主要包括气态烟以及近年来从烟水中提取的影响种子萌发的关键化学物质karrikins和glyceronitrile。该文围绕火烧的基本信息, 火烧信号对种子萌发的影响, 火烧信号在实践中的应用3个方面进行系统综述, 重点探讨了不同类别的火烧信号及其交互作用对种子萌发的影响。在系统总结火烧信号对种子萌发影响的研究进展的基础上, 提出未来的研究应与烟信号作用机理的探究以及全球变化等方面相结合, 旨在充分发挥火的生态服务功能, 为火的科学管理应用和退化生态系统恢复提供理论支撑。     

Experimental warming transforms multiple predator effects in a grassland food web

This experimental study tests new theory for multiple predator effects on communities by using warming to alter predator habitat use and hence direct and indirect interactions in a grassland food web containing two dominant spider predator species, a dominant grasshopper herbivore and grass and herb plants. Experimental warming further offers insight into how climate change might alter direct and indirect effects. Under ambient environmental conditions, spiders used habitat in spatially complementary locations. Consistent with predictions, the multiple predator effect on grasshoppers and on plants was the average of the individual predator effects. Warming strengthened the single predator effects. It also caused the spider species to overlap lower in the vegetation canopy. Consistent with predictions, the system was transformed into an intraguild predation system with the consequent extinction of one spider species. The results portend climate caused loss of predator diversity with important consequences for food web structure and function.     

Ocean acidification disrupts the innate ability of fish to detect predator olfactory cues

While ocean acidification is predicted to threaten marine biodiversity, the processes that directly impact species persistence are not well understood. For marine species, early life history stages are inherently vulnerable to predators and an innate ability to detect predators can be critical for survival. However, whether or not acidification inhibits predator detection is unknown. Here, we show that newly hatched larvae of the marine fish Amphiprion percula innately detect predators using olfactory cues and this ability is retained through to settlement. Aquarium-reared larvae, not previously exposed to predators, were able to distinguish between the olfactory cues of predatory and non-predatory species. However, when eggs and larvae were exposed to seawater simulating ocean acidification (pH 7.8 and 1000 p.p.m. CO₂) settlement-stage larvae became strongly attracted to the smell of predators and the ability to discriminate between predators and non-predators was lost. Newly hatched larvae were unaffected by CO₂ exposure and were still able to distinguish between predatory and non-predatory fish. If this impairment of olfactory preferences in settlement-stage larvae translates to higher mortality as a result of increased predation risk, there could be direct consequences for the replenishment and the sustainability of marine populations.
Ecology Letters (2010) 13: 68–75     

宁夏沙湖水生生态系统健康评估

以宁夏沙湖为例,选取pH值、悬浮物、溶解氧、化学耗氧量、生物耗氧量、总磷及铵氮等7项指标进行实测,并计算沙湖水体的综合污染指数,确定了水生环境的外部压力状态。计算并测量了沙湖水生生态系统在宏观尺度上的自由能、结构自由能,群落尺度上的浮游生物生物量、生产量及二者的比例关系,以判定其内部特征的变化情况。综合外部压力状态和内部特征指标体系的计算,结果表明,沙湖水生生态系统活力下降,生物周转速度慢,系统利用外界资源能力下降,种群增长受人为干扰,物种多样性下降,湖泊富营养化严重,并有进一步恶化趋势,目前处于不(或亚)健康状态。     

Nonconsumptive effects in a multiple predator system reduce the foraging efficiency of a keystone predator

Many studies have demonstrated that the nonconsumptive effect (NCE) of predators on prey traits can alter prey demographics in ways that are just as strong as the consumptive effect (CE) of predators. Less well studied, however, is how the CE and NCE of multiple predator species can interact to influence the combined effect of multiple predators on prey mortality. We examined the extent to which the NCE of one predator altered the CE of another predator on a shared prey and evaluated whether we can better predict the combined impact of multiple predators on prey when accounting for this influence. We conducted a set of experiments with larval dragonflies, adult newts (a known keystone predator), and their tadpole prey. We quantified the CE and NCE of each predator, the extent to which NCEs from one predator alters the CE of the second predator, and the combined effect of both predators on prey mortality. We then compared the combined effect of both predators on prey mortality to four predictive models. Dragonflies caused more tadpoles to hide under leaf litter (a NCE), where newts spend less time foraging, which reduced the foraging success (CE) of newts. Newts altered tadpole behavior but not in a way that altered the foraging success of dragonflies. Our study suggests that we can better predict the combined effect of multiple predators on prey when we incorporate the influence of interactions between the CE and NCE of multiple predators into a predictive model. In our case, the threat of predation to prey by one predator reduced the foraging efficiency of a keystone predator. Consequently, the ability of a predator to fill a keystone role could be compromised by the presence of other predators.     

Intraguild predation reduces redundancy of predator species in multiple predator assemblage

1. Interference between predator species frequently decreases predation rates, lowering the risk of predation for shared prey. However, such interference can also occur between conspecific predators. 2. Therefore, to understand the importance of predator biodiversity and the degree that predator species can be considered functionally interchangeable, we determined the degree of additivity and redundancy of predators in multiple- and single-species combinations. 3. We show that interference between two invasive species of predatory crabs, Carcinus maenas and Hemigrapsus sanguineus, reduced the risk of predation for shared amphipod prey, and had redundant per capita effects in most multiple- and single-species predator combinations. 4. However, when predator combinations with the potential for intraguild predation were examined, predator interference increased and predator redundancy decreased. 5. Our study indicates that trophic structure is important in determining how the effects of predator species combine and demonstrates the utility of determining the redundancy, as well as the additivity, of multiple predator species.     

太湖流域圩区水生态系统服务功能价值

以遥感图像、气象水文资料和实地水生态状况调查数据为基础,利用构建的评价指标体系对太湖流域圩区的水生态系统服务功能进行了评价,并分析其空间差异性。结果表明:太湖流域的圩区水生态系统服务功能价值为325.93×108元,以对生态系统的调节、维持功能等间接使用价值为主,是直接使用价值的6.18倍。主要受水域分布面积大小的影响,圩区水生态系统服务功能价值总量呈现出杭嘉湖区阳澄淀泖区湖西区浙西区武澄锡虞区浦西区太湖区浦东区的特点。太湖流域单位面积圩区水生态系统服务功能的平均价值为22.73元m-2a-1,整体表现为南高北低,西高东低的空间分布格局。