动物的反捕食策略

达尔文在《物种起源》中提出"自然选择"理论,在一定程度上解释了动物的行为规律。动物的反捕食策略作为行为生态学研究的主要内容之一,是自然选择的结果,使动物更加适应环境。正确应用行为生态学的研究方法能够有效理解和分析动物的反捕食策略。对动物的反捕食策略按照消耗能量的大小进行了分类总结,分别是隐蔽、逃避、自卫三大类。简要阐述了关于反捕食策略的最新研究动态,同时对动物的反捕食策略进行了简单的介绍与评价。     

四种鲤科鱼类对捕食胁迫行为响应的种间比较

为了比较早期捕食胁迫经历和当前环境中存在的捕食者对鱼类行为的影响,并考查这些影响是否存在种间差异,研究分别考查了测定环境(有、无捕食者存在)对有、无捕食胁迫经历的鳊(Parabramis pekinensis)、草鱼(Ctenopharyngodon idellus)、鲫(Carassius auratus)和中华倒刺鲃(Spinibarbus sinensis)等4种鲤科鱼类探索性、活跃性和勇敢性的影响。结果发现:早期捕食胁迫经历与当前环境条件对鱼类行为产生截然不同的影响,且存在较大的种间差异。无捕食胁迫经历的鳊、草鱼和中华倒刺鲃均会对陌生的捕食者乌鳢(Channa argus)做出行为响应,提示这3种鱼可能对陌生捕食者具有一定的识别能力,但这种识别与猎物鱼通过捕食胁迫经历获得的识别仍具有一定差距;具有捕食胁迫经历的鳊和中华倒刺鲃在空白环境中未表现出反捕食行为,可能是节约能量的一种策略。总体而言,草鱼对捕食胁迫经历和测定环境处理反应更为敏感,而中华倒刺鲃的反应则相对保守。但当周围环境中存在捕食者时, 4种鲤科鱼类均会通过维持较高运动状态的方式来应对捕食者。维持这种应激状态可能对猎物鱼...     

布氏田鼠母体青春期捕食风险应激对后代反捕食行为和HPA轴基础活动水平的影响

本研究以28日龄的青春期雌性布氏田鼠作为亲代实验动物,每天分别暴露于蒸馏水、兔尿和猫尿60min,连续18d,成年后与正常雄鼠交配.随后检测其子代在28日龄(青春期)和90日龄(成年期)时暴露于这3种气味源的行为反应,以及下丘脑促肾上腺皮质激素释放激素、血浆促肾上腺皮质激素和皮质酮的基础水平.结果显示:与母体青春期暴露...     

反捕食不能充分解释獐的集群行为(英文)

我在江西鄱阳湖国家自然保护区研究了獐 (Hydropotesinermis)的集群行为并检验了集群是动物反捕食对策的假说。如果这个假说成立 ,我们则可以做三个预测 :(1)集群大小应与植物覆盖度成负相关 ;(2 )集群动物比单独活动的动物有更多的时间取食 ;(3)集群动物与单独活动的动物相比 ,用于警戒的时间较少。结果表明 ,獐的集群在交配季节最大而在产仔季节最小 ,獐在短草期比在高草期倾向于形成较大集群。因此 ,本研究支持了第一个预测。但是 ,集群的獐和单独活动的獐在取食和警戒时间分配上并无差异。因此 ,本研究不支持第二和第三个预测。时间收支 (timebudget)分析显示 ,在非交配季节 ,带幼仔的雌性用于取食的时间较少但走动频繁。在交配季节 ,与单独活动的雌性相比 ,与雄性在一起的雌性用于取食的时间较少 ,而单独活动的雄性却比与雌性在一起的雄性花较多的时间用于观望寻找雌性。鉴于獐集群行为的复杂性 ,本研究认为 ,獐并不只因反捕食而集群 ,其它社会和生态因子在决定獐的集群行为中也很重要。     

四大家鱼幼鱼运动能力对捕食胁迫的响应

捕食胁迫(胁迫时长和胁迫强度)影响鱼类的运动能力,遭遇捕食者时猎物鱼的逃逸策略不尽相同。为考察鱼类运动能力对捕食胁迫的响应,本实验选取乌鳢(Channa argus)和南方大口鲶(Silurus meridionalis)为捕食者,青鱼(Mylopharyngodon piceus)、草鱼(Ctenopharyngodon idellus)、鲢(Hypophthalmichthys molitrix)、鳙(Aristichthys nobilis)四大家鱼幼鱼为猎物鱼。猎物鱼分别在无捕食(对照)、低捕食(隔网胁迫)和高捕食(直接胁迫)压力下接受捕食胁迫,胁迫时长分0、7和14 d三个水平,随后对比四大家鱼种间运动能力的差异,并考察四大家鱼幼鱼的稳定和非稳定游泳能力在不同捕食胁迫水平(胁迫时长和胁迫强度)下的适应性改变。结果表明：四大家鱼的稳定游泳和非稳定游泳能力之间存在权衡,应对捕食胁迫时以增强快速启动游泳能力为主,临界游泳速度有下降趋势;四大家鱼均表现为“C”型快速启动游泳模式,在快速启动过程中身体旋转主要在第1阶段完成,速度性能在第2阶段达到最大;在捕食压力下,四大家鱼的逃逸策略存...     

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.     

一类捕食-被捕食系统周期解的存在性

对于二维非自治捕食-被捕食系统,本文讨论了它的解的有界性,进而得到周期解和正周期解的存在性。     

暂时与群体分离的个体藏马鸡的反捕食警戒

通过与同伴分担捕食风险 ,生活在稳定群体中的个体动物可以获得长期的适合度利益 ,但同时它们不得不承担食物竞争所带来的潜在代价。这种代价常常取决于食物资源的类型。当好的食物资源出现时 ,一些个体可以离开群体而独享这种资源。了解这些临时游离者如何组织其反捕食行为 ,在进化生态学上是有意义的。藏马鸡 (Crossoptilonharmani)是西藏雅鲁藏布江中游高山灌丛植被的一种典型的非繁殖季节集群鸟类。野外观察表明 ,为了独享好的食物资源 ,一些个体常常远离当前群体的活动范围。分离事件更可能发生于大的群体 ,但其发生率与参与者的数量呈负相关 ;而参与分离的个体愈多 ,分离持续的时间就愈长。分离者的个体警惕水平随着临时群体大小的增加而下降 ,遵从在其它自然大小鸟类群体所发现的一般性规律。分离行为的发生和持续时间被认为是个体对当前食物回报和捕食风险进行权衡的结果。这种利益 -代价权衡也可以解释藏马鸡所具有的强烈集群行为     

一类非自治捕食-被捕食系统的全局渐近稳定性

本文研究了一类非自治捕食-被捕食的周期系统．当周期为ω＞0时,在某些条件下证明了该系统正周期解的存在唯一性和全局渐近稳定性．     

舍曲林对蚤状溞诱导型反捕食防御代内与代际可塑性的干扰效应

表型可塑性是指生物(尤其是单一基因型)在适应异质环境时表达出不同表型的能力,并且有遗传基础。环境变化调控表型可塑性既可以发生在个体发育进程中(称为代内表型可塑性),也能够以可遗传表型响应的形式持续多个生物世代(称为代际表型可塑性)。浮游动物枝角类常常受到来自鱼类的捕食风险影响而表现出诱导型防御的表型可塑性。诱导型防御的表达在很大程度上受到代谢稳态控制,因此枝角类的诱导型防御的表达容易受到内稳态代谢干扰物(例如抗抑郁药舍曲林)的影响。考虑到舍曲林在水中生物活性高且难以被降解;同时,枝角类世代周期较短,因此需要评估连续多代舍曲林暴露对枝角类反捕食防御代内以及代际可塑性的影响。结果发现：在代内可塑性方面,连续两代的舍曲林暴露放大了鱼类信息素诱导的蚤状溞体长减小趋势以及相对尾刺长度增长趋势,但是对鱼类信息素作用下的种群适合度参数无明显干扰。在代际可塑性方面,随着连续两代舍曲林的浓度上升,亲代经历鱼类信息素产下的子代继续响应鱼类信息素时,体长减小、相对尾刺长度增大,说明形态防御得到加强;同时种群净繁殖量以及种群内禀增长率下降的趋势被放大,由此可能抑制鱼类捕食风险下蚤状溞的种群丰度。上述结果表明,...     

Life history variation in Barents Sea fish: implications for sensitivity to fishing in a changing environment

• Under exploitation and environmental change, it is essential to assess the sensitivity and vulnerability of marine ecosystems to such stress. A species' response to stress depends on its life history. Sensitivity to harvesting is related to the life history “fast–slow” continuum, where “slow” species (i.e., large, long lived, and late maturing) are expected to be more sensitive to fishing than “fast” ones. We analyze life history traits variation for all common fish species in the Barents Sea and rank fishes along fast–slow gradients obtained by ordination analyses. In addition, we integrate species' fast–slow ranks with ecosystem survey data for the period 2004–2009, to assess life history variation at the community level in space and time. Arctic fishes were smaller, had shorter life spans, earlier maturation, larger offspring, and lower fecundity than boreal ones. Arctic fishes could thus be considered faster than the boreal species, even when body size was corrected for. Phylogenetically related species possessed similar life histories. Early in the study period, we found a strong spatial gradient, where members of fish assemblages in the southwestern Barents Sea displayed slower life histories than in the northeast. However, in later, warmer years, the gradient weakened caused by a northward movement of boreal species. As a consequence, the northeast experienced increasing proportions of slower fish species. This study is a step toward integrating life history traits in ecosystem‐based areal management. On the basis of life history traits, we assess the fish sensitivity to fishing, at the species and community level. We show that climate warming promotes a borealization of fish assemblages in the northeast, associated with slower life histories in that area. The biology of Arctic species is still poorly known, and boreal species that now establish in the Arctic are fishery sensitive, which calls for cautious ecosystem management of these areas.

     

Substances involved in the natural resistance of fish to infection–A review

Natural‘antibodies’are substances found in the blood of animals that have not been immunised against infective agents. However, exposure to these agents or to cross-reacting antigens may well have taken place. Fish contain naturally-occurring, relatively nonspecific, lectin-like proteins or glycoproteins, which are distinct from immunoglobulins, and which react with a wide variety of antigens and may confer some degree of immunity against natural infection. In most cases the cause of the antigenic stimulus is not obvious although the formation of these‘antibodies’may have been brought about by exposure to various micro-organisms. Many of these antibody-like molecules behave in a similar manner to immune antibodies or immunoglobulins and cross-react with specific carbohydrate moieties on the cell walls of bacteria, erythrocytes and certain other cellular antigens, due to the presence of similar antigenic determinants. It is difficult to ascribe an appropriate definition to the term‘natural antibody’. In fish, these‘antibodies’have been so designated on the basis of functional rather than structural criteria. Such naturally-occurring, low grade, antibody-like‘immune’substances include‘acute phase’proteins, lysozyme and chitinase, interferon, agglutinins, lysins, complement and properdin, precipitins, and non-immunoglobulin, lectin-like molecules. In addition to the above non-immunoglobulin materials, natural immunoglobulins identifiable as IgM have also been reported in fish. Furthermore, mucus contains many biochemical agents capable of reaction against infective organisms and thus providing the host with an immediate or a first line of defence mechanism. This review compiles some of the relevant information in the literature concerned with natural‘immune’substances, present in the serum and mucus of fish, involved in protection against pathogens. Wherever possible the basic physicochemical properties of these substances are indicated and their potential immunobiological functions discussed.     

沙生植物构型及其与抗风蚀能力关系研究综述

沙生植物在风蚀防治中起着至关重要的作用,长期的适应结果使其形成了特定的构型特征。构型特征不同,其抗风蚀的作用也不尽相同。过去的研究主要着眼于个体或群体组合,探讨沙生植物对近地面流场的影响和固阻沙作用。对于构型特征,主要从构件水平上探讨不同构型特征的沙生植物对环境的适应对策,而其抗风蚀作用的差异,还缺乏量化研究和系统探讨。本文评述了沙生植物构型及其与抗风蚀效果关系的研究进展,指出了今后需要优先深入研究的重点问题,从而为完善沙生植物抗风蚀机理提供科学依据。     

Training fish for restocking: refuge and predator training in the hatchery has limited benefits for a marine fish

Large numbers of hatchery-reared fish are released in stocking programmes; however, success is limited by high mortality. Predation is seen as the main cause of deaths but might be reduced by training fish before release to avoid predators and/or use refuge. In this study on a potential restocking species, yellowfin bream Acanthopagrus australis, the effects of predator training and refuge on the behaviour of fish in the hatchery were tested. In the first experiment, juvenile bream were exposed to predatory mangrove jack (Lutjanus argentimaculatus) fed exclusively on bream flesh while housed in tanks with and without refuge. Predator training altered fish behaviour when fish were re-exposed to predators, but the effects were subtle and varied between groups of fish. In contrast, refuge created strong and consistent changes in behaviour, significantly slowing down the amount of time that fish took to consume food. A second experiment focused on the effects of refuge. Bream were trained to use artificial seagrass or house bricks as refuge and then exposed to mangrove jacks in a laboratory predation experiment. When refuge was available, fish significantly slowed down their feeding rate. There was a small, transient increase in survival for fish given seagrass refuges, but this was irrespective of whether the bream were trained to use refuge. The results of this study indicate that the use of refuge may be innate and the benefits of refuge may be available to naive hatchery-reared fish or fish trained to use refuge shortly before release. This suggests that there is potential to improve post-release survival of fingerlings without time-consuming and expensive hatchery training.     

YOLO-Fish: A robust fish detection model to detect fish in realistic underwater environment

Over the last few years, several research works have been performed to monitor fish in the underwater environment aimed for marine research, understanding ocean geography, and primarily for sustainable fisheries. Automating fish identification is very helpful, considering the time and cost of the manual process. However, it can be challenging to differentiate fish from the seabed and fish types from each other due to environmental challenges like low illumination, complex background, high variation in luminosity, free movement of fish, and high diversity of fish species. In this paper, we propose YOLO-Fish, a deep learning based fish detection model. We have proposed two models, YOLO-Fish-1 and YOLO-Fish-2. YOLO-Fish-1 enhances YOLOv3 by fixing the issue of upsampling step sizes of to reduce the misdetection of tiny fish. YOLO-Fish-2 further improves the model by adding Spatial Pyramid Pooling to the first model to add the capability to detect fish appearance in those dynamic environments. To test the models, we introduce two datasets: DeepFish and OzFish. The DeepFish dataset contains around 15k bounding box annotations across 4505 images, where images belong to 20 different fish habitats. The OzFish is another dataset comprised of about 43k bounding box annotations of wide varieties of fish across around 1800 images. YOLO-Fish1 and YOLO-Fish2 achieved average precision of 76.56% and 75.70%, respectively for fish detection in unconstrained real-world marine environments, which is significantly better than YOLOv3. Both of these models are lightweight compared to recent versions of YOLO like YOLOv4, yet the performances are very similar.     

抗生素在环境中的转归及其生态毒性

抗生索被长期大量地用于人和动物的疾病治疗,并以亚治疗剂量添加于动物饲料长期用于动物疾病的预防和促进生长,大部分抗生紊不能完全被机体吸收,而有高达85％以上抗生素以原形或代谢物形式经由病人和畜禽粪尿排人环境,经不同途径对土壤和水体造成污染。最近研究显示在城市废水和表面水中检测到了抗生索的存在。但关于抗生素在环境中的分布、迁移和稳定性等的研究资料很少。环境中的抗生素会对环境生态系统包括细菌、水生生物、土壤生物和植物等产生危害,并产生大量耐药菌,对人类健康构成威胁。为评估抗生素在环境中潜在的危害,就抗生素在环境中的分布、转归及对环境和人的危害等方面进行综述,并对今后的研究方向作了探索。     

Interruptions to foraging and learning in a changing environment

Many resources are both stochastic and variable in their average profitability. Animals have to sample them to track their current states, but whether it is economic to attempt this depends on many factors. Furthermore, there are many interruptions and distractions from foraging (e.g. escape from predators, bad weather, displacement by competitors) which interfere with the acquisition of information. We present a dynamic model of foraging in a stochastic and varying environment, under the constant threat of interruption, to investigate this very general problem. A forager faces two foraging options, one of which provides a known and constant reward, the other providing a reward that is not only stochastic, but whose mean payoff varies in time. The forager has to learn which option has the highest current payoff by sampling. However, interruptions to foraging can occur at any time, the timing and duration of which are beyond the animal's control. When there is a small probability of foraging being interrupted, the forager should forage extensively on the unknown option, but as the probability of interruptions is increased, there is a sudden transition to foraging only on the known option. This occurs because interruptions affect both the level of information required to make exploitation of the unknown option profitable, and the ability to acquire and maintain that information. At what probability of being interrupted this threshold emerges is affected by the value of learning about the unknown option and the duration of interruptions. We discuss the generality of our results with reference to the pervasive problem of updating information in the face of different types of interruption. Copyright 1999 The Association for the Study of Animal Behaviour.     

Handed foraging behavior in scale-eating cichlid fish: its potential role in shaping morphological asymmetry

Scale-eating cichlid fish, Perissodus microlepis, from Lake Tanganyika display handed (lateralized) foraging behavior, where an asymmetric 'left' mouth morph preferentially feeds on the scales of the right side of its victim fish and a 'right' morph bites the scales of the left side. This species has therefore become a textbook example of the astonishing degree of ecological specialization and negative frequency-dependent selection. We investigated the strength of handedness of foraging behavior as well as its interaction with morphological mouth laterality in P. microlepis. In wild-caught adult fish we found that mouth laterality is, as expected, a strong predictor of their preferred attack orientation. Also laboratory-reared juvenile fish exhibited a strong laterality in behavioral preference to feed on scales, even at an early age, although the initial level of mouth asymmetry appeared to be small. This suggests that pronounced mouth asymmetry is not a prerequisite for handed foraging behavior in juvenile scale-eating cichlid fish and might suggest that behavioral preference to attack a particular side of the prey plays a role in facilitating morphological asymmetry of this species.     

The biology of seed discrimination and its role in shaping the foraging ecology of carabids: A review

Species of carabid (ground) beetles are among the most important postdispersal weed seed predators in temperate arable lands. Field studies have shown that carabid beetles can remove upwards of 65%–90% of specific weed seeds shed in arable fields each year. Such data do not explain how and why carabid predators go after weed seeds, however. It remains to be proven that weed seed predation by carabids is a genuine ecological interaction driven by certain ecological factors or functional traits that determine interaction strength and power predation dynamics, bringing about therefore a natural regulation of weed populations. Along these lines, this review ties together the lines of evidence around weed seed predation by carabid predators. Chemoperception rather than vision seems to be the primary sensory mechanism guiding seed detection and seed selection decisions in carabid weed seed predators. Selection of weed seeds by carabid seed predators appears directed rather than random. Yet, the nature of the chemical cues mediating detection of different seed species and identification of the suitable seed type among them remains unknown. Selection of certain types of weed seeds cannot be predicted based on seed chemistry per se in all cases, however. Rather, seed selection decisions are ruled by sophisticated behavioral mechanisms comprising the assessment of both chemical and physical characteristics of the seed. The ultimate selection of certain weed seed types is determined by how the chemical and physical properties of the seed match with the functional traits of the predator in terms of seed handling ability. Seed density, in addition to chemical and physical seed traits, is also an important factor that is likely to shape seed selection decisions in carabid weed seed predators. Carabid responses to seed density are rather complex as they are influenced not only by seed numbers but also by trait‐based suitability ranks of the different seed types available in the environment.