Final answer:
Speciation is the evolutionary process where one species splits into two or more species. It can occur via allopatric speciation, where physical barriers isolate populations, or sympatric speciation, where species diverge in the same environment.
Step-by-step explanation:
The process by which one species splits into two or more species is known as speciation. This biological phenomenon underlies the extraordinary diversity of life on Earth.
One common form of speciation is allopatric speciation, where geographic barriers like mountains, rivers, or other landscapes create isolation between two populations of the same species. For example, the different species of squirrels found on opposite sides of the Grand Canyon showcase allopatric speciation resulting from the canyon serving as a physical barrier.
Another form, sympatric speciation, occurs without physical separation. This can happen through genetic mutations or behavioral changes leading to reproductive isolation even though populations share the same environment. Charles Darwin portrayed speciation as a branching process in his work, visualizing how one species may evolve and diverge into multiple, reproductively isolated species over time.