环境生态学-第十二章互利共生

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Facultative
mutualism
The majority of mutualisms are nonobligatory and
opportunistic. They may be diffuse, involving a varying
mixture of species, as occurs between many pollinators and their plants.
蜜 蜂 与 花 的 协 同 进 化
传粉
Seed dispersal
Large seeds cannot be effectively wind-dispersed, and unless dispersal by water (as occurs in the coconut palm) occurs, such plants are dependent on animals for dispersal. Rodents, bats, birds and ants are all important seed dispersers.
种子扩散
大型种子无法有效的被风传布,除非靠水传布 (如椰树的种子),或依靠动物来散布。啮齿动
物、蝙蝠、鸟和蚂蚁都是重要的种子扩散者。
• 以植物种子为食的鸟类,特别是北方普遍分布的 鸫、鳾、松鸦和星鸦等,对于许多树种的扩散有 贡献,是自然界的“植树造林”能手。例如星鸦 嗜食橡树种子,而且秋天具有储藏橡子的习性, 常常收集数以百计的橡子,贮藏在远处不同的角 落,但却常常遗忘,这些被散布的橡子是橡树林 扩展的一个原因。有人证明,某些硬壳的植物种 子,在通过鸟类的消化道之后,更容易萌发;再 加上附上的鸟粪,连肥料也提供了,当然更容易 成活。
异型杂交植物需要将其花粉转移到同种植物
的柱头上,并接受同种植物的花粉。一些植
物种类靠风来传播花粉,如果植物生长在广 传 粉
大的植物种类单一的地方如草地和松林,这
种传播方式会很有效。但是大多数开花的双 子叶植物,依靠昆虫、鸟、蝙蝠或小型哺乳 动物来传播花粉,作为交换,这些动物或以 花蜜或以花粉本身为食。
and receive pollen from a conspecific. Some Pollination plant species rely on the wind to achieve
this, which can work acceptably well if
plants grow in large homogeneous stands of few species, as occurs in grasslands and pine forests, However, in most species of flowering dicotyledonous plants, insects, birds bats or small mammals are employed to transfer pollen from plant to plant, usually in exchange for either nectar or pollen itself as a foodsource.
有些互利共生者,如地衣,是永久性成 对组合,其中一方或双方不能独立生活。
专性互利共生
大多数共生者是专性共生,还有一些非
共生性的互利共生也是专性的,如蘑菇耕作蚁之间的互利共生。
共生:地衣
注意与共栖区别
• 共栖(commensalism) 两种不同的生物共 同生活,其中一方受益,另一方既不受益, 也不受害,此种现象称为共栖。如海洋中 体小的鮣鱼用其吸盘吸附在大型鱼类的体 表,被携带到各处,觅食时暂时离开大鱼, 这对大鱼无利也无害,但确增加了鮣鱼觅 食的机会
星鸦
松鸦

鳾(shi)
Symbiotic mutualists within animal tissues and cells
A number of animal species rely to some extent on mutualisms with mutualists which reside within their bodies. Ruminants (deer and cattle) possess a multi-chambered stomach in which bacterial and protozoan fermentation take place. In some termites, which feed on wood, the necessary breakdown enzymes are provided by bacterial mutualists. Intracellular bacterial symbionts which transform amino acids occur in a number of insect groups, including aphids and cockroaches.
L1 互利共生
要 点
互利共生是不同种两个体间一种正 的互惠关系,可增加双方的适合度。 互利共生可以是共生性的,生物体 以一种紧密的物理关系生活在一起。
互利共生 和 共生现象
种子植物和微生物间的共生关系现像,一般有两类型:根瘤(root nodule) 和菌根(mycorrhiza)。
Leabharlann Baidu
根瘤
菌根
• 苜蓿根上结的根瘤菌
兼性互利共生
互利共生的多数是非专性和机会性的。这些互利 共生可能是散开的,包含有不同的物种混合,如
许多传粉者与其传粉植物之间的互利共生。
An out crossing plant needs to transfer its
pollen to the stigma of a conspecific plant,
Obligate mutualism
Some mutualisms, such as lichens, are permanent pairings in which one or both partners cannot lead an independent life. Most symbioses are obligate, as are some nonsymbiotic mutualisms, such as those formed by fungus-farming ants.
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