Currently two concepts of species are generally accepted and are used. The first and primitive one is typological approach and the second is population approach (Biological Speciation Concept). When put in practice to study the mechanisms of variations these two concepts contradict with each other. In fact the BSC favores more an escape from competition and survival of fittest concept of Darwinian concept of evolution.
1. Allopatric Speciation
Speciation starts when a population is isolated from main population. There are two ways in which a population is isolated. They are isolated either by geographical barriers (Oceans, Mountain ranges, Deserts) or by living of organisms on the fringes of main population. Even adjacent population diverge into new species due to limited gene flow. This is called parapatric speciation. Both these processes of speciation is an escape speciation contrary to competitive speciation of Darwinian concept of evolution.
There are other ways of speciation which are not much evident as are allopatric and parapatric speciation, like sympatric speciation and ring speciation. These speciations are also an escape from competition. In sympatric speciation where two populaitons are overlapping and there is plenty of gene flow among them but they diverge because their hybrids are not fit enough.
Similarly, ring species interact with each other and there is gene flow but the end product is totally different from each others. All these speciations illustrate that organisms try to avoid competitions so they don't waste their energy.
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