Of the scenarios below, which represents the occurrence of evolution at its smallest scale?

• A. A change in allele frequency within a population over generations
• B. The appearance of similar traits in unrelated species due to convergent evolution
• C. The extinction of an entire species
• D. The formation of a new genus

Answer: (A)

Verified step by step guidance

1. Understand the concept of evolution at its smallest scale, which is microevolution. Microevolution refers to changes in allele frequencies within a population over generations.
2. Recognize that allele frequency refers to how common a particular allele is in a population. Alleles are different forms of a gene, and their frequencies can change due to mechanisms like mutation, natural selection, genetic drift, and gene flow.
3. Analyze the given scenarios: (1) A change in allele frequency within a population over generations, (2) The appearance of similar traits in unrelated species due to convergent evolution, (3) The extinction of an entire species, and (4) The formation of a new genus.
4. Evaluate each scenario: (1) represents microevolution, as it directly involves changes in allele frequencies within a population. (2) represents convergent evolution, which is a macroevolutionary process. (3) represents extinction, which is a large-scale event. (4) represents speciation, which is also a macroevolutionary process.
5. Conclude that the correct scenario representing evolution at its smallest scale is 'A change in allele frequency within a population over generations,' as it aligns with the definition of microevolution.