Parasitism, Mutualism, Commensalism, Predation Predator-Prey interactions

Parasitism: Interactions in which one organsism is harmed, but the other benefits.  A parasite may weaken its host; it rarely kills it host. More than 100 parasites live in or on the human species. When it causes a disease and sometimes the death of host, it is known as pathogen. Crown gall diease, caused by a bacterium, occurs in many plants.

·         Mutualism: Interactions in which both participants are benefited. The interdependent association between nitrogen fixing bacteria of the genus rhizobium and legume, is an example. Another example is the association between reef building coral animals and microscopic alage. The symbiotic alga is called Zooxan- thellae. Mycorrhizae is such an association between fungi and roots of 80% plants.

·         Commensalism: Interactions in which one participant benefits but the other is unaffected , e.g; relationship between two insects; silverfish and army ants, relationship between a tropical tree and many epiphytes, smaller plants such as mosses, orchids  and ferms that live attahed to the bark of the tree’s branches. The  epiphytes anchor itself to the tree to obtain adequate light and watr not for obtaining nutrients rom the tree.

Predation Predator-Prey interactions

   typically undergo oscillations. As predator population grows they may eat most of their prey; the predator population then crashes. Mimircy  is an adaptation by prey to predation. Plants possess adaptation that protect them from being eaten such as the presence of spines, thorns, tough leathery leaves or thick wax on the leaves. Other plants produe protective chemicals that are toxic to herbivores.  Animals also have adaptation to protct themselves from being eaten. Some animals blend into their surrounding to hide from predators. Besides warning coloration and chemical defenses, some animals live in herds to protect themselves.

 Competition   Interactions in which two organisms use the same resources, and those resources are insufficient to supply their combined needs, is called competition. Competition invariably results in a reduction in the number of one or both competitior.

Amensalim    Interactions in which one participant is harmed but the other is unaffected. For example, the shading out of one plant by a taller and wider one; the inhibition of one plant by secretions of another (known as Allelopthy).