Speciation is a process of the formation of new species due to the evolutionary processes in a certain population. According to the speciation hypothesis, a certain population moves from the initial population becoming adapted to a new environment. Genetic mutations, natural selection, and genetic flow trigger specific alterations in the populations causing complete speciation of the separated population that becomes a new species. There are four modes of geographic speciation:
- allopatric speciation is described by the split of the initial population into two groups isolated by geographic factors. These isolated species undergo further isolation and genotypic and phenotypic divergence occur;
- peripatric speciation is characterized by the complete isolation of a small group that forms a species in a new ecological niche;
- parapatric speciation is associated with the partial separation of population groups and putative mixing of the groups, whereas further genetic processes lead to their complete isolation;
- sympatric speciation is defined as a formation of new species from a certain population in the same geographic region. As a result, the initial and new species are not isolated by geographic factors.