Stickleback Practice Test

Genotyping a single gene locus like Eda is most efficiently done with targeted DNA analysis: amplify the Eda region by PCR and determine the genotype from the amplicon either by sequencing to read the exact variant(s) or by using a SNP-genotyping assay that detects known Eda variants. This direct approach zeroes in on the exact genetic differences that influence armor plating in sticklebacks, making it fast, accurate, and scalable to many individuals. Whole-genome sequencing of every sample, while informative, is much more resource-intensive and unnecessary when you only need the genotype at this one locus. Visual assessment of armor plates cannot reveal the underlying DNA sequence, and Southern blotting of random genomic regions isn’t a reliable or practical way to call genotypes at a specific locus.