How can natural selection lead to speciation over thousands of years?

The central idea here is that when populations are geographically separated, they will diverge from one another, both in the way they look and genetically. These changes might occur by natural selection or by random chance (i.e., genetic drift), and in both cases result in reproductive isolation.

The name of the instrument that the scientist uses is called a microscope.a microscope is used to view objects which is not visible to the naked eyes