Hi, Conch-Lers!

I have a question for those of you that know more about
DNA studies than I do; would subspecies and/or forms of a
species have DNA identical to the species proper, or would
there be some variation?  And, what can DNA comparison
tell us about the ability of two molluscs to produce
fertile offspring; would their DNA have to be identical
except for indication of the sex?

In extremely variable shells that are assumed to belong to
the same species, wouldn't the DNA indicate whether or not
they are all the same pecies?

Thanks,
Linda