Question

According to scientific thought, when does one species of organisms become two species?

Answer 1

Answer:

The biological species concept. According to the most widely used species definition, the biological species concept, a species is a group of organisms that can potentially interbreed, or mate, with one another to produce viable, fertile offspring. ... Hybrids are the offspring of two species.

Answer 2

Answer:

It happens when the two groups become sufficiently different and the two can no longer interbreed. A known example of speciation is the London underground mosquito where it formed a new species within the existing genus. There are examples in micro-evolution but not in macro-evolution.