Reproductive isolation between species prevents _____.

• A. genetic drift in small populations
• B. mutation from occurring
• C. natural selection within a population
• D. gene flow between populations

Answer: (D)

Verified step by step guidance

1. Understand the concept of reproductive isolation: Reproductive isolation is a mechanism that prevents different species from interbreeding and producing viable, fertile offspring. This is a key factor in maintaining species boundaries.
2. Identify the role of gene flow: Gene flow refers to the transfer of genetic material between populations. It occurs when individuals from one population migrate and breed with individuals from another population, leading to the exchange of alleles.
3. Connect reproductive isolation to gene flow: Reproductive isolation prevents interbreeding between populations of different species. This, in turn, stops the exchange of genetic material (gene flow) between these populations.
4. Eliminate incorrect options: Genetic drift, mutation, and natural selection are processes that occur within populations and are not directly prevented by reproductive isolation. These processes are unrelated to the prevention of gene flow between species.
5. Conclude that the correct answer is 'gene flow between populations,' as reproductive isolation specifically acts to block the exchange of genetic material between species.