>Are there any other good characterizations of DNA for species description?
 
Other relatively low-expense approachs involve molecular markers such as
restriction fragment length polymorphisms (RFLPs) and allozymes (actually
proteins rather than DNA).
 
RFLPs use various DNA-cutting enzymes that cut a particular known sequence.
For example, one enzyme may cut a DNA strand every time it finds GTAC.  If
there has been a mutation in one species where GTAC used to be, making it
different, or if a mutation makes GTAC where the sequence used to be
different, adding that enzyme to the DNA from differnt species will produce
pieces of different lengths.
 
Allozymes are also based on mutations.  A mutation in a gene may not affect
the function of the product but may still affect its structure in an
unimportant part of the protein.  By comparing the size and structure of
various enzymes from a possible new species to those in known species, you
can see whether there are consistent differences.
 
A more expensive approach is to obtain a DNA sequence for rapidly evolving
DNA sequences.  For example, the spacer sequences between many genes mutate
very rapidly in many organisms and would be expected to differ between
different species.
 
David Campbell
 
"Old Seashells"
 
Department of Geosciences
CB 3315 Mitchell Hall
University of North Carolina at Chapel Hill
Chapel Hill NC 27599-3315
USA
 
919-962-0685
FAX 919-966-4519
 
"He had discovered an unknown bivalve, forming a new genus"-E. A. Poe, The
Gold Bug