Why do scientists consider the Abert’s and Kaibab squirrels to be examples of speciation?

• A. They are the result of artificial selection by humans.
• B. They are examples of convergent evolution, where unrelated species develop similar traits.
• C. They are two populations that interbreed freely and share identical genetic traits.
• D. They are populations that became geographically isolated and evolved into distinct species due to genetic divergence.

Answer: (D)

Verified step by step guidance

1. Understand the concept of speciation: Speciation occurs when populations of the same species become isolated from each other and evolve independently, leading to the formation of distinct species. This can happen due to geographic, behavioral, or genetic factors.
2. Identify the key factor in the example: The Abert’s and Kaibab squirrels are geographically isolated by the Grand Canyon, which acts as a physical barrier preventing interbreeding between the two populations.
3. Explain the role of geographic isolation: Geographic isolation prevents gene flow between populations, meaning that genetic traits cannot be exchanged. Over time, mutations, natural selection, and genetic drift lead to genetic divergence.
4. Discuss genetic divergence: Genetic divergence refers to the accumulation of genetic differences between populations. These differences can result in distinct physical traits, behaviors, or adaptations, eventually leading to the formation of separate species.
5. Conclude why this is an example of speciation: The Abert’s and Kaibab squirrels evolved into distinct species due to their geographic isolation and subsequent genetic divergence, which aligns with the definition of speciation.