Standing genetic variation is alleles already present in a population prior to new selection pressures.

• A. It refers to new mutations
• B. It consists of alleles already present in the population
• C. It is identical to genetic drift
• D. It only occurs in polyploid species

Answer: (B)

Standing genetic variation is about the alleles already present in the population before any new selection pressures appear. This means the gene pool already contains a range of alternative forms at many genes, and when the environment changes, some of those pre-existing variants may become advantageous and increase in frequency. This explains why populations can adapt quickly without waiting for new mutations to arise.

Think of it like having a toolkit already in place: when the rules of the game change, you can immediately start using the parts you already have, rather than hoping a new part will show up. New mutations can still contribute over time, but standing variation provides the ready-made material selection can act on right away. It’s not the same as genetic drift, which is random fluctuation in allele frequencies, and it isn’t restricted to polyploid species—standing variation exists in any population.