Which type of speciation takes place when two populations are separated by a physical barrier, leading to genetic divergence over time?

The type of speciation that occurs when two populations are separated by a physical barrier, such as a mountain range or a body of water, is known as allopatric speciation. This separation creates distinct environmental conditions for the two populations, which can lead to genetic divergence as they adapt to their unique surroundings.

As each population evolves independently, genetic differences accumulate due to mutation, natural selection, and genetic drift. Over time, these genetic changes can become significant enough that, even if the physical barrier were removed, the populations could no longer interbreed successfully. This reproductive isolation solidifies the emergence of two distinct species.

In contrast, sympatric speciation involves the emergence of new species within the same geographic area, often through mechanisms such as polyploidy or behavioral differences that reduce gene flow. Parapatric speciation occurs when populations are adjacent but not completely separated, with some level of gene flow still possible. Peripatric speciation is similar, but it often involves a smaller population on the edge of a larger population that becomes isolated and diverges. In allopatric speciation, the clear and effective separation by a physical barrier creates the ideal conditions for the evolution of distinct species.