Gregor Mendel (1822-1884), Father of Genetics.
Quote
"Species do not transform one into the other. They show stability from generation to generation, and my experiments demonstrate that fact. Isn’t anyone listening?"


Here's an example of one type of experiment he did. One can google and find out more.


One only has to view the reality of the fossils themselves. An abundance of examples of many different kinds of fossils to look at for those who are interested: