Interactions within Ecosystems, Biology tutorial


Populations of various organisms live altogether in a community that altogether having the nonliving factors of the environment forms an ecosystem. The organisms interact among themselves in different manners for survival.

Types of Interactions:

Interactions among organisms which characterize specific communities have mount as an outcome of their evolutionary trend. The animals, plants, protists, fungi and bacteria which live altogether in communities have changed and adjusted to one other continually over a period of millions of years. Most of the communities are much identical in their species composition and appearance over broad regions. For illustration, the open savanna which stretches across much of Africa comprises most of the plant and animal species which coexist over thousands of square kilometers. Interactions among these organisms, some of which have evolved over millions of years, take place in a similar way all through these grassland communities. A few of these interactions comprise:

  • Predator/Prey interaction
  • Symbiosis
  • Commensalism
  • Parasitism
  • Competition (that is, Interspecific and Intraspecific) 

At the same time, mutualism and commensalism are positive interactions others, similar to parasitism, predation and competition are the negative interactions.

Predator-Prey Interaction:

Predator-prey interactions are interactions among organisms in which one organism feeds on the other. A good illustration is a lion hunting a gazelle in the open Savanna of Africa. The predators encompass natural features and build up recognizable strategies which help them hunt and imprison their prey. The strategies which prey use to avoid being eaten are not so obvious. A few animals though, employ chemical defenses to ward off predators. Venomous snakes, lizards and fishes are renowned illustrations. As well, bees, predatory bugs, wasps, scorpions, spiders and most of the other arthropods contain chemicals which they utilize to defend themselves and to kill their prey.

The dart-poison frogs of the family Denrobatidae generate toxic alkaloids in the mucus which covers their skin so powerful that some micrograms will kill a person when injected to the bloodstream. Among plants¸ obvious structures are build up such as spikes, thorns, prickles to discourage browsers such as vertebrate herbivores from feeding on them. Several grass deposit silica in their leaves to make them too tough to eat. Plants similar to in the potato and tomato family (that is, Solanacea) are rich in steroids and alkaloids, whereas some others like in the milk weed family (Asclepiadeceae) tend to produce a milky sap which deters herbivores from eating them.

Symbiotic Interactions (Symbiosis):

Symbiotic relationships are those in which the two or more types of organisms live altogether in often elaborate and more or less permanent relationship. Illustrations of symbiosis comprise lichens, that are the associations of some fungi having green algae or Cyanobacteria and Mycorrhizae made from the association among fungi and the roots of most kinds of plants. Here the fungi expedite the absorption of specific nutrients through the plants and the plants give the fungi having carbohydrates.

The main types of symbiotic relationships comprise:

  • Commensalism
  • Mutualism
  • Parasitism

a) Commensalism: In nature, the individuals of one species are frequently physically joined to those of the other. For illustration, epiphytes are plants which grow on the branches of other plants. In common, the host plant is unharmed whereas the organism which grows on it benefits.

Marine barnacles grow up on other often actively moving sea animals and are therefore taken passively from place to place. On land commensal interactions take place among certain birds termed as Oxpeckers and grazing animals, like cattle or Rhinoceros.

b) Mutualism: In mutualism, each and every organism comprised in the symbiotic relationship advantages. Leafcutter ants in the tropics are known to eliminate a quarter or more of the total surface of the plants in a given region. They don't eat the leaves however take them to their underground nests where they chew them up and immunize them by the spores of specific fungi.

c) Parasitism: Parasitism is a symbiotic relationship that is harmful to the prey organism and advantages to the parasite. The parasite is much smaller than the prey and remains closely related to it. Both the vertebrates and invertebrates are parasitized through members of many various phyla of animals and protists.


Competition as an interaction takes place among organisms in a community of an ecosystem when they need the similar resource which is in short supply termed as resource competition or when the organisms seeking a resource harm one other in the procedure even when the resource is not in short supply. This is termed as interference competition. Competition can be categorized into Interspecific or Intraspecific.

Interspecific Competition:

Interspecific competition signifies to the interactions among individuals of various species, both of which need the similar resources that is in short supply. Interspecific competition is often greatest among organisms which get their food in similar manners. We find as an outcome which green plants compete by other green plants for sunlight, nutrient and water, herbivores with other herbivores and carnivores with carnivores. Moreover, competition is more acute among similar organisms which between ones that are less identical.

Intraspecific Competition:

Intraspecific competition takes place if individuals of a single species or of the similar species compete for a resource in short supply. Food and mating partners give illustrations of causes for intraspecific competition. Competition for space might take place in several animals such as for nesting the sites, wintering sites or sites safe from the predators.

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