Here's an example from my own evolutionary algorithms. The following are the genotypes of related organisms:
The original species:
The phenotype is:
So the ending 11 or so digits don't do anything, and thus mutate all over the place. Other sections don't matter much either. =(1,b) to have 8 subtracted later is at most able to change that e + -8 to an e + -7, and thus the 1b digits in the genotype vary greatly. In fact, the digits are different in every subspecies.
Junk DNA is actually junk.