Final answer:
Recombination frequency is used to determine the relative order of genes and distances between them on a chromosome. Cytogenetic mapping can estimate approximate distances, while physical maps provide detailed information about physical distances using advanced techniques.
Step-by-step explanation:
Geneticists determine the relative order of genes and distances between them on a chromosome by using recombination frequency. This method involves counting the number of offspring exhibiting nonparental genotypes, which indicates a crossover event between two linked genes. The higher the frequency of crossover, the further apart the genes are located on the chromosome.
In addition to recombination frequency, cytogenetic mapping is another technique used to estimate the distances between genetic markers. By analyzing stained sections of chromosomes under a microscope, scientists can acquire information about the relative location of genes within a genome, although it only provides approximate distances, not the exact number of base pairs. Physical maps, on the other hand, offer detailed insight into the actual physical distance between genes, derived from methodologies like radiation hybrid mapping and sequence mapping.