More genes assort independently than there are chromosomes. First demonstration by Curt Stern. Chromosomes show evidence of physical exchange. Genetic Maps 1. Crossing over occurs more frequently as the distance between two genes increases.
Genetic map shows relative position of genes.
Recombination map uses frequency of crossing over 3. Linked genes are too close to assort independently. Recombination at the gene level. The gene sequence in chromosome 1 changes from ABC to Abc. Blending heredity .