If one compares the base sequences of related genes from different species, one is likely to find that corresponding exons are usually conserved, but the sequences of introns are much less well conserved.
Explanation:
A gene consists of two parts called the exons and introns.
Exons code for the gene products while introns lie between two consecutive exons and do not code for any gene product.
Exons are highly conserved within a species while introns are less conserved and help in diversifying individuals within same species.
Introns are spliced of during the mRNA processing to give rise to a mature mRNA that will code for a protein.
