Gene order is the permutation of genome arrangement. A fair amount of research has been done trying to determine whether gene orders evolve according to a molecular clock (molecular clock hypothesis) or in jumps (punctuated equilibrium). By comparing gene orders in dissimilar organisms, scientists are able to develop a molecular phylogeny tree. When organisms have similar gene orders, meaning they have likely diverged recently, it is called synteny.
Some research on gene orders in animals' mitochondrial genomes reveal that the mutation rate of gene orders is not a constant in some degrees.[1]
Methods for genome mapping, determining the gene order, include:
All of these methods can lead to a gene sequence or a DNA sequence by which genes can be identified and compared.