How do biogeographical barriers promote speciation?

Biogeographical barriers promote speciation by isolating populations and preventing gene flow.

Biogeographical barriers, such as mountains, oceans, and deserts, can physically separate populations of a species, preventing them from interbreeding. This isolation can lead to genetic divergence, as each population may experience different environmental pressures and mutations. Over time, these genetic differences can accumulate, leading to reproductive isolation and the formation of new species.

One example of biogeographical barriers promoting speciation is the Galapagos finches. These birds are believed to have evolved from a common ancestor, but the different islands they inhabit have different environmental conditions, such as food availability and predation pressure. This has led to the evolution of different beak shapes and sizes, which has allowed the finches to exploit different food sources. Over time, these differences have become so pronounced that the finches on different islands can no longer interbreed.

Another example is the formation of the Isthmus of Panama, which separated the Atlantic and Pacific oceans around 3 million years ago. This barrier prevented marine organisms from moving between the two oceans, leading to the evolution of distinct species on either side. This process is known as allopatric speciation, and it is a common way in which biogeographical barriers promote speciation.

Overall, biogeographical barriers can promote speciation by isolating populations and allowing for genetic divergence. This can lead to the formation of new species over time, as each population adapts to its unique environment.