The intraspecific trophic competition can be not only individual, t. to occur between separate individuals. The competition for food is entered also by groups of genetically uniform individuals (a colony, a family). Such competition designate group (or intergroup). The competition for food between two families of wolves which hunting sites are blocked can be its example.
V. N. drew an important conclusion that fight for existence is the real fact that it as a result inevitably leads to adaptive evolutionary transformations. For this reason V. N. 's works were recognized classical subsequently and entered many reports of works on the evolutionary theory.
Not always it is possible to draw an accurate distinction between the competition and direct fight for food. However the general criterion of such division is that at the competition organisms fight indirectly, and direct fight consists in their direct collisions as it is accurately expressed in fight between a predator and the victim. Told treats and all other kinds of the competition and direct fight.
The classical studied example of the individual interspecific competition is fight between two closely related types of infusorians of Paramecium caudatum and P. aurelia. At cultivation of these types in one culture in 16 days in a test tube only individuals of P. aurelia bred. Individuals of that look won the competition for food because possess bigger growth rate.
Fight for food between herds of deer, families of wolves and packs of jackals can be an example of the intergroup trophic competition of two types. This kind of the competition is noted among high-organized animals and, as a rule, has no acuity.
The intraspecific trophic competition has most acuity as it is entered by the individuals identical under the morfofiziologichesky constitution and therefore the having need for identical food. This situation which is put forward by Darwin was confirmed by a set of experiences on protozoa, plants and multicellular animals.
The interspecific trophic competition is the important reason of improvement of the morfofiziologichesky organization. For example, evolution of two species of the predators competing for identical food goes on the way of development of ability to fast run, improvement of organs of hearing, sight, sense of smell.
The trophic competition is caused at animals by needs for identical food, at plants — in the same nutrients (water, mineral salts) and the solar energy necessary for photosynthesis. The trophic competition happens between individuals of both one, and different types.
The Topichesky form of the competition has individual and group character. In the second case against the general abiotic conditions there is a competitive fight between groups of genetically similar organisms (clones, broods, families). So, at a sharp cold snap there can be destruction entirely broods of baby birds in nests, but what are in more warmed nests will remain. The outcome of such intergroup competition will consist in improvement of ways of care of posterity.
The intraspecific trophic competition can arise not only in the conditions of big density. It is always observed 'where food interests of individuals that can occur and at their relative sparseness in space face. It is characteristic for the animals who are actively protecting the hunting sites, especially for predators with aggressive behavior.
Direct fight against abiotic factors is caused by negative impact on organisms of the various climatic. conditions (low and high temperatures, drought, remoistening), harmful chemicals (salts, acids), lack of oxygen, light etc.