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. (SOURCE)
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. One evolutionist source describes this essential requirement:
(Prof. Dr. Ali Demirsoy, Kalıtım ve Evrim, p. 689)Prof. Ali Demirsoy
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.
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.