Speciation is an evolutionary process that leads to the formation of a new species.

Speciation is the evolutionary process by which populations evolve to become distinct species.  

Some important things about species:

A species is a group of individuals that are genetically able to mate in nature and produce fertile offspring. 

Members of a species belong to the same gene pool.

For a new species to form there must be separation of the gene pool of the species from the gene pool of the parent population.

How it connects to Evolution: 

Evolution has given rise to the diversity of species we see on Earth. Evolution is a process that explains how organisms have diversified and descended from earlier forms of organisms over time. 

Definition from exam

Speciation is the process of forming new biological species. 

Definition:

Reproductive isolation means that members of different species cannot interbreed and produce viable offspring. This can be pre-zygotic or post-zygotic, meaning before or after fertilization. 

The inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences. 

Reproductive isolation allows for different species to diverge from common ancestors and drive evolution.  

Examples:

An example of reproductive isolation is in changes of bird song from different species of finch of the Galapagos island. Females of one species of finch do not recognize the bird song of males. This is a pre-zygotic barrier.