Isolation between populations due to physical barriers.

Isolation between populations due to physical barriers.

• A. Temporal isolation
• B. Geographic isolation
• C. Behavioral isolation
• D. Mechanical isolation

Answer: (B)

Geographic isolation is when physical barriers such as mountains, rivers, or long distances physically separate populations, preventing them from interbreeding. When these barriers stop gene flow between groups, each population can drift genetically and adapt to its own environment, leading to divergence over time and eventually reproductive isolation—a process known as allopatric speciation. The other forms involve differences in timing, mating signals, or anatomical fit, not the presence of a barrier that blocks contact between populations, so they don’t describe separation by geography.

Geographic isolation is when physical barriers such as mountains, rivers, or long distances physically separate populations, preventing them from interbreeding. When these barriers stop gene flow between groups, each population can drift genetically and adapt to its own environment, leading to divergence over time and eventually reproductive isolation—a process known as allopatric speciation. The other forms involve differences in timing, mating signals, or anatomical fit, not the presence of a barrier that blocks contact between populations, so they don’t describe separation by geography.