Living beings interact among themselves in the same species, with the members of the other species, and with the components of the abiotic environment in an ecosystem. Interaction between the members of the same species is called as Intraspecific whereas the interaction among individuals of different species is called as Interspecific.
In intraspecific interactions members of the same species interact either for mutual benefits or for self-benefits. These interactions include communications through visual, vocal, or chemical means; Care and Protection of young; courtship; and sexual competitions.
Individuals in the same species communicate among themselves through visual gestures, and through speech or through producing specific sounds. It is very commonly observed in case of birds. Members of some species like insects, produce pheromones to attract their mates.
Many birds use fancy displays, including brightly-coloured feathers, “dances,” etc. to “show off” for the opposite sex. Sexual selection is selective pressure by members of the opposite sex. For example, perhaps the females of a certain species of bird prefer a male who is brightly-coloured or who has an extremely-long tail.
Sexual selection may actually work in the opposite direction of natural selection, as when, for example, that same brightly-coloured or long-tailed male is thereby more visible and vulnerable to predators. In spiders, special drumming patterns used in species-specific courtship rituals help to distinguish a courting male from dinner.
In many species individuals are observed to have parental care which varies from species to species. A special case of intraspecific relationship is social and colonial species of animals, which have dominance hierarchies which are maintained through interactions among the members of a particular colony.
In intraspecific interaction, individuals may compete over food, water, light, space, safe sites, or mates. This type of interaction may also be called as intraspecific competition. It is an important factor which limits the size of population of many species. It is a particular type of competition in which members of the same species compete for the same resource in an ecosystem. Such a resource may be food, light, nutrients, and space.
One can observe that two trees of the same species that grow close together compete for sunlight, water and nutrients in the soil. Lower growth rate and low seed output may be the result of this competition. It is through natural selection that trees adapt to grow taller or to develop larger root systems.
The competition interaction may be Exploitation Competition, and Interference Competition. Grasshoppers provide exploitation competition by eating grass and depriving other grasshoppers of the vicinity. In this case grasshoppers do not interact directly with each other; rather they cause a negative effect on the growth and development of others by reducing a resource.
In the Interference Competition, individuals interact indirectly. This has been observed in cases of territorial animals. In this case some animals have been observed to exploit a resource, like food base, thus actively preventing others from exploiting that resource.
The intraspecific competition affects carrying capacity of a population. Carrying capacity is the maximum population level which can be supported by the environment of a particular area. There is another type of interaction seen among plants and animals and this is called as Allelopathy.
It is seen that some plants often secrete inhibitory chemicals into the surrounding soil to prevent the growth of other plants nearby. This is called Allelopathy. Amur Honeysuckle and Black Walnut are two species that are especially notorious for producing allelopathic chemicals.