What is a key trade-off with microsatellites?

• A. They are highly polymorphic but fewer loci.
• B. They are abundant and stable.
• C. They cannot detect population structure.
• D. They require no laboratory work.

Answer: (A)

Microsatellites provide a lot of information per location because each locus is highly polymorphic due to a high mutation rate, so you see many alleles at a given marker. But the number of loci that are reliably usable and easy to genotype across a genome is comparatively small, so you end up with many alleles per locus but fewer loci overall. That combination—high polymorphism at each locus but a limited number of usable loci—is the key trade-off. The other statements don’t fit: microsatellites aren’t inherently abundant and stable (their high mutation rate makes them less stable), they can be used to detect population structure, and they require lab work for PCR and sizing.