Question

When we will conclude that a new species has evolved ?

Answer 1

Separate groups of organisms belonging to the same species may adapt in different ways to better exploit diverse environments or resources. They also may evolve varied characteristics for attracting mates. That is, different groups evolve in different directions. Over time, these groups or populations may become so different that they can no longer breed together--separate species are formed.

Emphasis on " They can NO LONGER BREED together".