Exemplar Problems

Question:

Explain how allopatric speciation occurs, including the role of geographic isolation and genetic drift. Provide an example.

Answer:

Allopatric speciation occurs when populations of a species become geographically isolated, preventing gene flow between them. Over time, genetic differences accumulate due to independent evolutionary pressures in each isolated population. Genetic drift, which is the random change in allele frequencies within small populations, can also play a significant role in allopatric speciation. An example is the formation of different species of finches on the Galápagos Islands. Each island had different environmental conditions, leading to variations in beak shape and size in response to available food sources, resulting in the evolution of distinct finch species.