The movement of individuals into an area that is already occupied by a population is known as ...

• A. Immigration
• B. Emigration
• C. Gene pool
• D. Primary succession

Answer: (A)

Immigration is the movement of individuals into a population from elsewhere. When organisms immigrate, they join an existing group, increasing the local population and potentially introducing new genetic material into the gene pool, which can alter allele frequencies over time. Emigration would be leaving the area, not entering it. The gene pool refers to the set of all alleles in a population, not the act of moving into a place. Primary succession describes ecological change starting from bare substrate, not from an already inhabited area.