Summary

In this module, we looked at landmark historical experiments that began the task of mapping phenotypes to specific loci in the genome. This included linkage mapping experiments in Drosophila melanogaster, early linkage mapping in humans using pedigrees, mapping via molecular markers, and, most recently, genome-wide association studies.

Although the test-cross strategy used by T.H.Morgan and other early geneticists is no longer commonly used to map phenotypes to chromosomes, it’s nonetheless useful to understand the concept of linkage. Modern mapping experiments via SNP association still are based on the principle that little recombination occurs between loci that are close together on the same chromosome, so when SNPs are co-inherited with a phenotype it suggests they may be tightly linked.