When populations are divided by some geographic obstacle, the gene pools (representing the populations’ genetic structure) of populations living in the two different environments may be found to change. The further apart populations move from one another, the greater the potential increase in the differences between them. Isolation giving rise to population changes may be geographic, economic, cultural or climatic.227 (See Geographic Isolation theory, the.)
These two populations separated from one another for whatever reason—generally geographic isolation—may lose the ability to interbreed with each other. As a natural consequence of this, the genetic combination of each population remains restricted. Evolutionists refer to every effect that prevents mating and effective fertilization between populations as isolation or as an isolation mechanism. According to evolutionists, isolation that restricts reproduction is essential for species formation.228 One evolutionist source describes this essential requirement:
No species can separate from another in the absence of this; and if ever it did, it could never survive independently. What if all animals mated freely with one another and were able to reproduce among themselves? The result would be a convergence leading to the disappearance of all zoological units. In other words, no dog, horse, cat or cow would have a separate existence; they would be just combinations of all animals. Because the distinction between animals and human beings would be lost, there would be many human-like animals and animal-like humans. Eventually a most fascinating mongrel would emerge from the combination of all these. Since reproduction is unrestricted on the streets we see various mongrel breeds among dogs. Since dogs all belong to separate breeds they produce mongrels among themselves. That is why dog breeders take care to use only pedigree breeds in order to maintain specific characteristics. If this were not done, then peculiar mongrel breeds from a mixture of all dogs.229
Evolutionists try to account for the origin of species in terms of isolation. But the question of how so many thousands of species emerged on Earth is exceedingly hard for evolutionists to answer. Therefore, they deliberately use the concept of isolation as the mechanism that brings new species into being. However, no new species comes into being through isolation. That merely enables the emergence of different variants, stemming from a narrowing of the gene pool. At the basis of speciation, there is no genetic incompatibility stemming from division into two groups. These life forms will still belong to the same species, in terms of their overall genetic information.
Therefore, there is nothing about the speciation that supports the theory of evolution, which claims that all living species evolved from the simple to the complex in a random manner. This means that if evolution is to be taken seriously, it must be able to point to mechanisms that increase genetic information. It must be able to explain how life forms originally lacking eyes, ears, a heart, lungs, wings, feet or other organs and systems managed to acquire them, and where the genetic information describing these organs and systems came from.
No doubt that the division of an already existing species into two, suffering a loss of genetic diversity, has absolutely nothing to do with this.
The fact that subspecies are not evolving into new species is actually admitted even by evolutionists. For that reason, evolutionists describe examples of variations within a species and of speciation by division as micro-evolution. (See Micro-evolution.) Micro-evolution is used in the sense of variants emerging within an already existing species. However, the use of the term evolution here is deliberately intended to mislead, because there is no such process going on. What is happening consists of different combinations of genetic information that already exists in that species’ gene pool being distribution in different populations of individuals.
Evolutionists need to answer such questions as, “How did the first species come into existence?” and “How did the categories above species, the classes, orders, families etc. initially come into existence?” that.227 Özer Bulut, Davut Sağdıç, Elim Korkmaz, Biyoloji Lise 3, p. 152.