捕食驯化对胭脂鱼和中华倒刺鲃游泳行为、应激和免疫功能的影响

鱼类对环境的行为和生理适应能力与其在自然界的资源变动状况密切相关, 研究选取胭脂鱼(Myxocyprinus asiaticus)和中华倒刺鲃(Spinibarbus sinensis)幼鱼为研究对象, 考察1周捕食者(乌鳢, Channa argus)驯化对2种鱼类的运动能力(最大匀加速速度)、特异(血浆IgM水平)和非特异免疫(血浆溶菌酶含量)指标和抗氧化能力(血浆超氧化物歧化酶活性)的影响, 及在有无捕食者急性暴露两种条件下的驯化和非驯化鱼群自发游泳行为(游泳速度、运动时间比和个体间距离)和应激反应(血浆皮质醇水平)。研究发现: (1)总体上中华倒刺鲃比胭脂鱼有更快的游泳速度、更为活跃的自发游泳行为、更高的血浆皮质醇和IgM水平; (2)1周捕食驯化导致两种鱼类血浆皮质醇水平、特异免疫和非特异免疫水平的上升, 并且中华倒刺鲃比起胭脂鱼表现的更加明显; (3)急性捕食者暴露导致血浆皮质醇水平上升, 个体间距离下降, 但后者仅在非驯化组有所体现。研究表明: (1)捕食驯化鱼类通过皮质醇动员特异和非特异免疫应对应激, 这些生理和行为的改变可能有利于鱼类增强避敌能力或加快非致死捕食损伤的快速恢复。这表明捕食驯化可作为潜在的增殖放流前的生态锻炼; (2)2种鱼类的行为、免疫等生理基础状态及其对外界刺激的响应程度不尽相同, 未来相似的环境变化可能对两种鱼类的资源产生不同影响。     

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...     

饥饿对中华倒刺鲃幼鱼代谢、个性和集群的影响

在自然界中,环境变化、季节更替和人为因素造成食物资源时空分布的不均一性,导致鱼类经常面临食物资源短缺的环境胁迫,对其能量代谢和行为造成一定影响。为考察食物资源短缺下暖水性鲤科鱼类能量代谢、个性与集群行为的应对策略及其可能的内在关联,选取中华倒刺鲃(Spinibarbus sinensis)幼鱼为实验对象,分别测定饥饿组(2周)和对照组(维持日粮)在处理前后实验鱼的标准代谢率(Standard metabolic rate,SMR)、个性行为(勇敢性、探索性和活跃性)以及实验处理后的集群行为(凝聚力和协调性)。研究发现:(1)饥饿组和对照组实验过程中实验鱼SMR均显著下降,但仅饥饿组实验鱼SMR具有重复性;(2)饥饿导致中华倒刺鲃幼鱼勇敢性、探索性、活跃性均显著增加;(3)饥饿导致群体成员间距离缩短,游泳速度及其同步性上升。研究表明:饥饿后的中华倒刺鲃不仅适应性降低SMR以减少能量消耗,而且呈现出更高的勇敢性、探索性和活跃性以利于获取食物资源;饥饿迫使中华倒刺鲃群体提高凝聚力和协调性,可能有助于提高群体的生存能力。     

两种生态相关猎物鱼个性的种间差异及其捕食者效应

为探究不同猎物鱼个性的种间差异及其捕食者效应, 实验以乌鳢(Channa argus)为天然的捕食者, 选取自然界通常形成混合种群的高体鳑鲏(Rhodeus ocellatus)和麦穗鱼(Pseudorasbora parva)作为猎物鱼, 设置有捕食者和无捕食者处理组开展同质园实验; 之后, 分别测定了经历捕食环境处理的两种猎物鱼的探索性、活跃性和勇敢性3类个性特征, 分析两种猎物鱼个性特征的种间差异及其环境依赖性。结果发现: (1)高体鳑鲏和麦穗鱼个性存在显著的种间差异, 不管是否经历捕食者处理, 高体鳑鲏的探索性、活跃性和勇敢性均显著强于麦穗鱼(P<0.05); (2)捕食者处理导致高体鳑鲏和麦穗鱼探索性和勇敢性有增强的趋势, 但对二者的活跃性均无显著影响(P>0.05); (3)捕食者处理弱化了高体鳑鲏和麦穗鱼不同个性特征的种间差异, 强化了各自不同个性特征的偶联。结果提示: 两种猎物鱼个性特征的种间差异显著且均具有捕食者效应, 有捕食者环境下两种猎物鱼个性特征的种间差异变小, 表现出趋同化适应的趋势。     

不同捕食者暴露对鲫幼鱼行为、运动和形态特征的影响

自然界中鱼类的捕食者种类繁多,为验证猎物鱼针对不同捕食者是否会做出相异的反捕食策略选择,选取鲫（Carassius auratus）幼鱼为猎物鱼,乌鳢（Channa argus）和胡子鲶（Clarias fuscus）为捕食者,将鲫幼鱼分别暴露于空白（对照）、乌鳢、胡子鲶和双捕食者（同时存在乌鳢和胡子鲶）环境中持续2个月,随后考查不同组鲫幼鱼的生长、行为特征、形态和运动能力等指标之间的差异。结果表明：经过2个月的捕食胁迫处理,鲫幼鱼的自发运动、隐蔽场所利用率和勇敢性等行为指标在4个组之间均未表现出显著性差异。相比对照组,乌鳢、胡子鲶和双捕食者暴露组鲫幼鱼的快速启动反应时滞显著缩短（P<0.05）;但所有处理组中仅乌鳢暴露组鲫幼鱼的快速启动120ms移动距离（S_120ms）和体高（BD）显著高于对照组（P<0.05）。另外鲫幼鱼的临界游泳速度（U_crit）和活跃代谢率（M_O2active）在各组之间也未表现出显著差异。乌鳢暴露组鲫幼鱼快速启动能力的提升可能与形态上体高的提高有关;另外相比临界游泳能力,快速启动能力可能在鱼类逃避捕食者过程中更为关键;鲫幼鱼表现出对乌鳢的反应最为明显,可能与乌鳢口裂较大,给鲫幼鱼带来的威胁更大有关。整体而言,应对捕食胁迫时,鲫幼鱼仅表现出形态和快速启动能力的反捕食响应,其行为特征的保守性可能是对生长作出的妥协,这对于鱼类适应生境中长期存在的捕食胁迫十分关键。     

群体成员大小差异对不同生境鲤科鱼类集群行为的影响

为研究群体成员大小差异对不同喜好生境鱼类集群行为特征的影响, 实验分别以鳊(Parabramis pekinensis)和中华倒刺鲃(Spinibarbus sinensis)幼鱼为实验对象, 比较分析4尾等大小(E)和不等大小(2大2小, NE)实验鱼群体的自发游泳速度、空间分布以及对恐吓刺激反应等集群行为参数的差异。结果显示: (1)和鳊相比, 中华倒刺鲃有更高的自发游泳速度、速度同步性和排列方向的极性, 但二者对恐吓刺激的反应率及反应的协调一致性相似; (2)当群体成员大小出现差异时, 两种鱼群体排列方向的极性不受影响, 且大小个体成员间的速度及其同步性均没有差异, 但整体的速度同步性与等大小群体相比有所下降; (3)个体间距离数据显示, 个体大小差异不会影响两种鱼群体的凝聚力; (4)群体成员在两种鱼群中偏好位置不同, 当群体成员大小不同时, 大个体成员更偏好占据领头鱼位置; (5)群体成员大小的差异导致两种鱼对刺激的反应率下降。研究表明: 中华倒刺鲃具有更高的活跃性、更好的群体运动的协调性, 可能与其流水生境相关; 当群体成员大小出现差异时, 成员不分大小在整体上协调运动的速度和方向, 并保持群体有较高的凝聚力, 但两种鱼类自发游泳速度调整策略截然不同(鳊大小个体速度妥协趋同, 而中华倒刺鲃低速个体速度提高); 群体成员大小差异导致鱼群对恐吓刺激的反应率有所下降, 可能原因包括体形差异导致的社会因素造成敏锐性下降、信息交流效率受阻和(或)集群收益代价出现分化影响一致决策的形成等。     

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.     

中华倒刺鲃和胭脂鱼游泳行为、应激和免疫能力对短期禁食的响应

近年来,长江流域鱼类资源急剧下降,而有关鱼类对环境变化的行为和生理响应对于评估环境变化对种群动态的影响具有重要意义,相关研究亟待开展。选取中华倒刺鲃(Spinibarbus sinensis)和胭脂鱼(Myxocyprinus asiaticus)幼鱼为实验对象,考察两种鱼类在1-2周禁食后的自发群体运动时间比、游泳速度、个体间距离、最大匀加速速度、溶菌酶含量、鱼体免疫球蛋白(IgM)水平、血清皮质醇水平和超氧化物歧化酶活性的响应。研究发现：(1)相比之下,胭脂鱼的自发游泳行为表现不太活跃,游泳能力和IgM水平更低,超氧化物歧化酶SOD水平更高;(2)胭脂鱼在正常摄食条件下比中华倒刺鲃生长更慢,但是在1-2周短期禁食条件下其体重下降更少;(3)1-2周的短期禁食结束后,两种实验鱼的SOD活性和游泳能力变化不明显,但是其IgM水平和皮质醇都提高,胭脂鱼表现不及中华倒刺鲃;(4)胭脂鱼的溶菌酶含量在1-2周短期禁食后明显提高,但是中华倒刺鲃的溶菌酶含量没有受到1-2周短期禁食的显著影响。研究表明：(1)相比于中华倒刺鲃,胭脂鱼不太活跃,免疫和运动能力也更低,当食物充足时生长优势不明显,但在食物短缺时,营养物质和能量损失更少;(2)两种实验鱼的生理机能(比如游泳行为和免疫功能)对短期禁食有不同的响应,胭脂鱼更加不敏感(溶菌酶除外)。总体而言,研究表明同样的食物资源波动可能导致同一水域不同鱼类不同的生态后果,更多鱼类的相关研究亟待开展。     

光倒刺鲃、中华倒刺鲃和倒刺鲃氨基酸成分和微量元素的测定

本文对光倒刺鲃,中华倒刺鲃和倒刺鲃18种氨基酸和8种微量元素进行了分析,结果表明:这三种鱼是营养价值很高、滋味很鲜美的鱼类。并且,根据结果氨基酸组成比例,可为该鱼的人工饲养等方面的研究提供理论依据。     

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。     

Discriminating between Hungry and Satiated Predators: The Response of Guppies (Poecilia reticulata) from High and Low Predation Sites1

Fixed anti-predator activities are costly because they limit the ability of the prey to take advantage of short term temporal patchiness in predation pressure. The ability to discriminate between hungry and satiated predators and a flexible response to the differential threat can help to lower the costs of anti-predator behavior. In this study Trinidadian guppies (Poecilia reticulata) were found to distinguish between hungry and satiated predators. In Trinidad, populations of guppies experience different levels of predation from piscivorous fish. Individuals taken from populations with chronically high predation pressure responded stronger to the hungry predator than those from low predation sites.     

Interspecific infanticide deters predators

It is well known that young, small predator stages are vulnerable to predation by conspecifics, intra-guild competitors or hyperpredators. It is less known that prey can also kill vulnerable predator stages that present no danger to the prey. Since adult predators are expected to avoid places where their offspring would run a high predation risk, this opens the way for potential prey to deter dangerous predator stages by killing vulnerable predator stages. We present an example of such a complex predator–prey interaction. We show that (1) the vulnerable stage of an omnivorous arthropod prey discriminates between eggs of a harmless predator species and eggs of a dangerous species, killing more eggs of the latter; (2) prey suffer a minor predation risk from newly hatched predators; (3) adult predators avoid ovipositing near killed predator eggs, and (4) vulnerable prey near killed predator eggs experience an almost fourfold reduction of predation. Hence, by attacking the vulnerable stage of their predator, prey deter adult predators and thus reduce their own predation risk. This provides a novel explanation for the killing of vulnerable stages of predators by prey and adds a new dimension to anti-predator behaviour.     

萼花臂尾轮虫对晶囊轮虫反捕食行为及形态响应的母体效应

为研究轮虫通过母体效应诱导能否产生行为响应, 以萼花臂尾轮虫(Brachionus calyciflorus)为例, 研究其反捕食漂浮行为响应的母体效应。通过控制轮虫母体在捕食者诱导液中的暴露时间及带卵状态, 收集母体产生的后代, 再将这些后代再次用捕食者诱导液处理, 观察后代的漂浮行为及形态特征。研究发现: 暴露于捕食者诱导液诱导较长时间的母体产生的后代个体, 当再次暴露于捕食者诱导液时, 其产生的行为响应强于没有母体暴露经历的后代; 母体暴露时间越长, 后代形态和行为响应均更加强烈。研究显示萼花臂尾轮虫可通过母体效应产生漂浮行为响应。     

Prey or predator: 0+ perch (Perca fluviatilis) in the trade-off between food and shelter

The 0+ cohort of perch can split into a slow-growing planktivorous and a fast-growing piscivorous cohort during their first months of life. Both cohorts are, however, vulnerable to predation by piscivorous fish. Laboratory experiments were performed to test the behavior of 0+ perch as a predator of cyprinids, and in the trade-off between food and shelter from the threat of predators. In the foraging trials, 0+ perch attacked bream faster than they did carp, and vegetation hampered the aggression against bream. In the second experiment, the habitat selection of two size classes of 0+ perch under the threat of predation was monitored. Overall, vegetation structures were preferred by both size classes of 0+ perch. When small fish were offered to the 0+ perch as food, the open water becomes more attractive. The results of the habitat use trials further show that the two size cohorts of 0+ perch may also differ in their behavior, in that the availability of fish as food becomes more important than the shelter of vegetation structures for the larger perch.     

Inspection behaviour and inter-individual cooperation in juvenile qingbo: the effects of prior predator exposure and food deprivation

The predation pressure and food availability to which individuals are exposed during their life histories shape inspection behaviour in animals. In this study, we aimed to test whether such behaviours varied with prior experience (predation, starvation or both treatments) or measurement condition (with or without the presence of a predator; here, the snakehead fish, Channa argus) in the fish species Spinibarbus sinensis, known as qingbo. Unexpectedly, prior predator experience showed no significant effect on inspection behaviour as demonstrated by either the frequency or the duration of each activity outside shelter or on cooperation as demonstrated by the inter-individual distance or synchronization of speed. This may have been due to the different adjustments in behaviour among individuals (more shelter use vs. more inspection), the predator treatment used in the present study (exposure to caged predator rather than direct predation) and/or a species-specific strategy in the qingbo. The starved fish displayed shorter inspection latency, increased inspection behaviour and greater cooperation when measured without the predator; however, when measured in the presence of the predator, the starved fish showed increased inspection frequency but shorter inspection duration, possibly due to the compromise between energy needs and predation risk. Similar to those of the predation group, the fish from the double-treated group showed no difference in inspection behaviour compared to the control group under the predator-absent condition, while the high-frequency, short-duration inspection behaviours remained the same as in the starved group. These findings suggested that the adjustment of inspection behaviour and related cooperation are rather complicated according to either predator experience or food deprivation, partially due to the inter-individual differences in behavioural adjustment and/or different environmental conditions.     

Predator-prey shell games: large-scale movement and its implications for decision-making by prey

Many classical models of food patch use under predation risk assume that predators impose patch-specific predation risks independent of prey behavior. These models predict that prey should leave a chosen patch only if and when the food depletes below some critical level. In nature, however, prey individuals may regularly move among food patches, even in the apparent absence of food depletion. We suggest that such prey movement is part of a predator-prey "shell game", in which predators attempt to learn prey location, and the prey attempt to be unpredictable in space. We investigate this shell game using an individual-based model that allows predators to update information about prey location, and permits prey to move with some random component among patches, but with reduced energy intake. Our results show the best prey strategy depends on what the predator does. A non-learning (randomly moving) predator favors non-moving prey – moving prey suffer higher starvation and predation. However, a learning predator favors prey movement. In general, the best prey strategy involves movement biased toward, but not completely committed to, the richer food patch. The strategy of prey movement remains beneficial even in combination with other anti-predator defenses, such as prey vigilance.     

Preference for Cannibalism and Ontogenetic Constraints in Competitive Ability of Piscivorous Top Predators

Occurrence of cannibalism and inferior competitive ability of predators compared to their prey have been suggested to promote coexistence in size-structured intraguild predation (IGP) systems. The intrinsic size-structure of fish provides the necessary prerequisites to test whether the above mechanisms are general features of species interactions in fish communities where IGP is common. We first experimentally tested whether Arctic char (Salvelinus alpinus) were more efficient as a cannibal than as an interspecific predator on the prey fish ninespine stickleback (Pungitius pungitius) and whether ninespine stickleback were a more efficient competitor on the shared zooplankton prey than its predator, Arctic char. Secondly, we performed a literature survey to evaluate if piscivores in general are more efficient as cannibals than as interspecific predators and whether piscivores are inferior competitors on shared resources compared to their prey fish species. Both controlled pool experiments and outdoor pond experiments showed that char imposed a higher mortality on YOY char than on ninespine sticklebacks, suggesting that piscivorous char is a more efficient cannibal than interspecific predator. Estimates of size dependent attack rates on zooplankton further showed a consistently higher attack rate of ninespine sticklebacks compared to similar sized char on zooplankton, suggesting that ninespine stickleback is a more efficient competitor than char on zooplankton resources. The literature survey showed that piscivorous top consumers generally selected conspecifics over interspecific prey, and that prey species are competitively superior compared to juvenile piscivorous species in the zooplankton niche. We suggest that the observed selectivity for cannibal prey over interspecific prey and the competitive advantage of prey species over juvenile piscivores are common features in fish communities and that the observed selectivity for cannibalism over interspecific prey has the potential to mediate coexistence in size structured intraguild predation systems.     

Effects of an infectious fungus, Batrachochytrium dendrobatidis, on amphibian predator-prey interactions

The effects of parasites and pathogens on host behaviors may be particularly important in predator-prey contexts, since few animal behaviors are more crucial for ensuring immediate survival than the avoidance of lethal predators in nature. We examined the effects of an emerging fungal pathogen of amphibians, Batrachochytrium dendrobatidis, on anti-predator behaviors of tadpoles of four frog species. We also investigated whether amphibian predators consumed infected prey, and whether B. dendrobatidis caused differences in predation rates among prey in laboratory feeding trials. We found differences in anti-predator behaviors among larvae of four amphibian species, and show that infected tadpoles of one species (Anaxyrus boreas) were more active and sought refuge more frequently when exposed to predator chemical cues. Salamander predators consumed infected and uninfected tadpoles of three other prey species at similar rates in feeding trials, and predation risk among prey was unaffected by B. dendrobatidis. Collectively, our results show that even sub-lethal exposure to B. dendrobatidis can alter fundamental anti-predator behaviors in some amphibian prey species, and suggest the unexplored possibility that indiscriminate predation between infected and uninfected prey (i.e., non-selective predation) could increase the prevalence of this widely distributed pathogen in amphibian populations. Because one of the most prominent types of predators in many amphibian systems is salamanders, and because salamanders are susceptible to B. dendrobatidis, our work suggests the importance of considering host susceptibility and behavioral changes that could arise from infection in both predators and prey.     

Predator recognition and defence strategies in crucian carp, Carassius carassius

Crucian carp from populations that lack piscivores are extremely vulnerable to predation. However, in the presence of piscivores these fish develop an inducible morphological defence, a deep body. This switch from a vulnerable, shallow-bodied morph to a morphologically defended morph makes this species very suitable for investigations of anti-predator strategies, and trade-offs between morphological and behavioural defences. To address these questions, we performed eight different experiments. We found that crucian carp exhibited fright responses to chemical cues from unfamiliar predators (northern pike, perch) when these were fed prey that contained alarm substance (for northern pike: crucian carp, roach; for perch: crucian carp). Cues from small pike that were fed prey that lacked alarm substance (swordtails) caused no significant fright response whereas cues from larger pike with the same diet did. Perch on a chironomid diet elicited weaker but significant fright responses. Starved predators caused as strong fright reactions as recently fed ones did, whereas no response was exhibited towards nonpredatory fish (roach, crucian carp). Crucian carp were able to detect the presence of pike after cues had been diluted to an equivalent of 21 000 l, and larger predators elicited stronger fright responses. Prior experience of predators decreased fright responses. In particular, individuals from populations that coexisted with northern pike responded less to chemical cues from northern pike than individuals without prior experience did. Thus, crucian carp may use both alarm-substance related and predator-related cues to identify predators. Further, they were able to discriminate between large and small predators. Finally, individuals from populations that coexist with predators exhibit less pronounced fright responses. These fish have an induced morphological defence, a deep body, which most likely decreases the need for strong antipredator behaviour.