环境生态学---第十章 捕食的性质.ppt

J1 捕食的性质 要 点 捕食的定义 捕食可定义为摄取其他个体（猎物）的全部或部 分为食。这一广泛的定义包括（i）典型的捕食者 ，在袭击猎物后迅速杀死而食之；（ii）草食者 ，只消费对象个体的一部分；（iii）寄生者，与 单一对象个体（寄生）有密切关系，通常生活在 寄主的组织中。 捕食 一个物种的成员以另一物种成员 为食,被捕食者常常被杀死. 狭义捕食: 动物吃动物 广义捕食则包括动物以植物为食的现象（ 植食）以及茅膏菜、捕蝇草、瓶子草、猪笼 草和狸藻等少数植物捕捉昆虫将其消化以吸 取含氮物质的情况。 Predators can be categorized as (i) herbivores which consume plant tissue, (ii) carnivores which food in animal tissue and (iii) omnivores which feed on both. The difference between animals and plants as prey types required different physiological and behavioral adaptations, and has lead to repeated evolutionary divergence between carnivorous and herbivorous lineages. Carnivores and herbivores 肉食者和 草食者 捕食者可以划分为（i）消费植物组织的草食者，（ii） 摄食动物组织的肉食者和（iii）既摄食植物组织也摄食 动物组织的杂食者。动物、植物食性的差异需要不同 的生理和行为适应，从而导致肉食者与草食者世系之 间反复的进行分歧。 Predators vary in the number of species of prey they will feed on, with some species being specialists, whilst others are more generalist. Generally, parasites tend to be more specialist than true predators and herbivores tend to be more specialist than carnivores. Generalists and specialists 泛化种和 特化种 捕食者随其摄取猎物的数量多少而变化，某些捕 食者是特化种，而另一些是泛化种。一般来说， 寄生者比典型捕食者更为特化、而草食者比肉食 者更为特化。 健壮的肉食者 新西兰美利诺羊 Do predators and parasites regulate the population size of their prey? This is not as simple q question as it may appear. There are two main issues: (I) the effect of any one predator may only be a small component of the total mortality causes affecting a prey species, so removal of the predator will have only a minor effect; (ii) predation may kill animals which were going to die anyway, so there will be no impact on the final prey population size. However, in a number of cases there is clear evidence that predators have a considerable impact on prey numbers. The impact of predators on prey population size 捕食者对猎物 种群大小的 影响 捕食者和寄生者是否能够调节其猎物种群的大小 呢？这一问题并不像看上去的那么简单。有两种 主要观点：（i）任一捕食者的作用，只占猎物种 总死亡率的很小一部分，因此去除捕食者对猎物 种仅有微弱效果；（ii）捕食者只是杀死了对象 种中即将死亡的个体，所以最终对猎物种群大小 没有影响。然而，在一些例子中确有明显证据表 明捕食者对猎物数量有重要影响。 猎物呢？ The Lotka_Volterra predator-prey model is a simple mathematical model representing the interaction between predators and their prey. It makes three simplifying assumptions: (i) there is only one predator and one prey species involved in the interaction; (ii) prey numbers increase if the number of predators falls below a threshold and decrease if there are more predators; and (iii) predator numbers increase if the number of prey rises above a threshold and decrease if there are fewer prey. This simple model makes an interesting prediction: predator and prey populations will tend to cycle, as is observed in natural predator- prey dynamics. Lotka-Volterra predator-prey model Lotka- Volerra捕食 者-猎 物模型 Lotka-Volterra捕食者-猎物模型是描述捕食者与 猎物间相互关系的一个简单的数学模型。这一模 型做了三个简单化假设：（i）相互关系中仅有一 种捕食者与一种猎物；（ii）如果捕食者数量下 降到某一阈值以下，猎物数量就上升，而捕食者 数量如果增多，猎物种数量就下降和（iii）如果 猎物数量上升到某一阈值，捕食者数量就增多， 而猎物种数量如果很少，捕食者数量就下降。这 一简单的模型做了一个有趣的预测：捕食者和猎 物种群动态会发生循环，就像在自然的捕食者-猎 物种群动态中所观察到的那样。 Related topicsNatality, mortality and population Predator behavior and prey growth (H2) response (J2) Population dynamics fluctuations, The nature of parasitism (K1) cycles and chaos (H4) The dynamics of parasitism K2) 相关主题 出生率、死亡率和种群增长（H2） 种群动态波动、周期和混沌（H4） 捕食行为和猎物反应（J2） 寄生的性质（K1） 寄生的动态（K2） Given a choice between two potential prey types, a predator which is optimizing its effort should choose the most profitable prey. Evidence from common shore crabs and pied wagtails demonstrates that prey of a size which return the greatest energy reward per unit time are preferred over smaller and larger individuals. Key Notes Profitability of prey J2 J2 P PRED ATOR BEHAVIOR AND RED ATOR BEHAVIOR AND PREY RESPNSE PREY RESPNSE J2 捕食行为和猎物反应 要 点 猎物收益率 面对两种类型猎物的选择时，捕食者要获得最佳捕获 努力，就应该选择收益最大的猎物。真蟹和白脊 令 的证据表明捕食者优先选择能使其在单位时间内获得 最大能量的一定大小的猎物，而不是比该体积更大或 更小的猎物。 鸟鸟 Predators may alter or switch their preference for a particular prey species depending on the abundance of that species, When this occurs, common prey are consumed super proportionately whilst less common prey are largely ignored. Switching between prey types 猎物转换 依据猎物种数量的多少，捕食者有时会转换其选择而 捕食某一特定的猎物种。这时捕食者主要捕食优势种 猎物而大大忽略其他猎物。 It is generally expected that at high densities of prey, a predators consumption rate will increase and then flatten out as prey saturation occurs, this relationship is termed the functional response and may adopt different patterns, which can be stereotyped into three classes: functional responses I, II and III. The effect of prey density functional responses 猎物密度影响 功能反应 一般认为在高猎物密度下，捕食者的摄食率会增加， 然后随猎物饱和达到最大速度。这种关系称为功能反 应，可能采用多种模式，传统上分为三种类型：功能 反应I、II和III。 To obtain food, a predator must first search for its prey and then handle (catch, process and eat) it. Diet width can be regarded as being determined by a balance between a generalist strategy of searching for a wide variey of prey (relatively easy) and a specialist strategy of searching for one type of prey and handling that very efficiently. Optimal foraging theory assumes that evolution will have optimized predator behavior to maximize the rate of energy gain and makes predictions about how we should expect predators to balance searching and handling. Searching and handling 搜寻和处理 为得到食物，捕食者必须首先搜寻猎物，然后处 理（抓住、加工和吃掉猎物）。可以认为捕食者 食谱的宽度是由泛化种对策与特化种对策之间的 权衡决定的。泛化种对策捕食者寻找多种猎物（ 相对容易），特化种对策捕食者寻找一类猎物， 非常有效的处理它。最佳觅食理论假定进化会最 优化动物行为以使其获得的能量效率最大，从而 做出捕食者如何权衡搜寻与处理的预测。 Predator-prey experiments in the laboratory indicate that in simple environment, either (i) predators are able to consume all prey individuals, or (ii) the predator population becomes extinct and the prey survives. If, however, the habitat is more complex some prey refuges and coexistence between predators and prey may occur. In corollary with the role of habitat patchiness in maintaining coexistence between competing species (see topic I1), environmental heterogeneity is likely to be of critical importance in allowing predators and prey to coexist. Heterogeneity and prey refuges 异质性和猎物 隐蔽处 实验室捕食者猎物实验表明在一个单纯环境中 ，或（i）捕食者吃掉所有猎物个体，或（ii）捕 食者种群消亡而猎物存活。然而，如果环境更为 复杂，则一些猎物个体可能在猎物避难所中摆脱 捕食，从而出现捕食者猎物的共存。由于生境 斑块在维持竞争种间共存中所起的作用（见I1） 推论，环境异质性很可能在允许捕食与猎物共存 中具有关键的重要意义。 Predators do not solely respond to the distribution and density of prey they may also respond to the distribution of competing predators. Predators will tend to aggregate in the most profitable patches, but predator crowding will reduce the patch profitability until it is better to move to another less crowded patch. The ideal free distribution theory suggests that predators should move among sites until profitability is equal. The ideal free distribution 理想自由分布 捕食者并不单独对猎物的分布与密度做出反应 它们对与之竞争的捕食者的分布也会反应。捕 食者趋向于聚集在最有利可图的斑块中，但捕食 者之间的拥挤会降低斑块的有利度，直到移到另 一块不太拥挤的斑块中去会更好。理想自由分布 理论认为捕食者会在各分布区间移动，直到各区 有利度相等。 Related topics The mature of competition (I1) The nature of predation J1) Plants defend themselves from predation in two main ways: (i) toxicity and unpalatablity, and (ii) defensive structures. There is a vast variety of chemical ammunition found in the plant kingdom used to defend plants against attacks from predators and parasites. These s