What method of speciation occurs when a geographical barrier separates populations?

The method of speciation that occurs when a geographical barrier separates populations is known as allopatric speciation. In this process, populations of the same species become isolated due to physical barriers such as mountains, rivers, or distances that prevent individuals from mating. This isolation leads to the divergence of the populations over time, as they adapt to their specific environments and accumulate genetic differences.

Through this process, new species can emerge due to factors such as natural selection, genetic drift, and mutations that operate independently in each isolated population. This form of speciation is considered one of the most common ways that new species arise, as it emphasizes the role of geographical separation in biodiversity.

The other methods of speciation involve different mechanisms, such as reproductive isolation occurring without geographical barriers, seen in sympatric speciation, or instances where populations are separated but remain in close proximity to one another, as is the case in parapatric and peripatric speciation. However, none of these processes emphasize the role of a geographical barrier as distinctly as allopatric speciation does.