Molecular systematics is very powerful. Its
useful because some genes are common to all organisms,
or almost all. For instance, we can make a comparison
among organisms as different as oak trees and people
and bacteria using an RNA polymerase, a gene that
is needed in all organisms. If we want to do any
kind of analysis that stretches across such morphologically
distinct organisms, we can use DNA as a basis for
doing that. Mark Wilkinson, Associate
Keeper of Zoology, Natural History Museum, London
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