Effects of Crossing Over on Linked Genes

Linked genes are carried on the same chromosome and hence should be inherited together. But due to crossing over, some of the linked genes separate and are transmitted on different chromosomes. During crossing over, sections of chromatids of a bivalent intertwine and may break off. Some of these sections get rejoined to different chromatids, thus separating genes that were previously linked. Fusion of the few gametes containing chromatids whose genes have changed places in this way will produce new combinations (recombinants).

However, the majority of the gametes that fuse contain chromatids whose gene linkage has not been interfered with by crossing over. Crossing over results in chromosomal mutations, which in turn cause variations.