What is Chromosome Mapping in phenotypic trait?

Chromosome Mapping : By noting how often a gene segment associated with a specific phenotypic trait crossed over during meiosis, or the recombination frequency, geneticists were able to determine relative distance between the loci of the genes on the chromosomes. Using this technique, they could construct chromosome maps or gene maps for each organism, specifying the chromosome number and the site on the chromosome for each trait. Alleles that are separated by crossing over one percent of the time are described as being one map unit apart.

Efforts at chromosome mapping have culminated in the human genome project that is underway today. The project uses sophisticated technology to map the 35,000 to 40,000 genes in the human genome.