> Many workers use ethanol to preserve samples for later study of DNA.  Some use 70% some 95%.

70% is marginal.  95% is better; 100% is a lot more expensive than 95%
(much harder to make).  Freezing or keeping it alive are also options,
as are various more obscure chemical recipies.

You may need to take measures to ensure that the ethanol penetrates
rapidly and is not significantly diluted by water from the tissues.
For example, snails with opercula and clams with tightly-sealing
valves might be able to clamp shut until they die and the DNA starts
degrading before the ethanol penetrates.  Cutting them open in some
fashion will address this.

You might also want to change the ethanol to compensate for dilution.

The post office doesn't like ethanol, so if you need to mail your
material to a lab you might take it out of the ethanol bottle and just
wrap it in some ethanol-soaked paper towers and put it in a sealed
non-breakable container.

Ethanol dissolves several inks-beware as you label.

How to analyze-depends on how much money you have, how big a sample
you can collect, and exactly what your question is.

Try looking to see if anyone has done work on related species,  This
will give some useful ideas as to what worked and possibly what didn't
work.

A very widely used comparison is cytochrome oxidase sequence.  There
are good primers available and lots of comparative data, but just like
anything else there are variations between different groups as to how
large a difference is seen between species and known cases of anomaly.
 Other genes are worth considering as well; again, seeing what has
worked for someone in related taxa is good.  Microsatellites seem very
good at distinguishing closely related populations, but there are
questions on their interpretation and coming up with primers in an
unstudied group may be difficult.  Allozymes are less sensitive than
gene sequence but can be cheaper for a large number of comparisons.
Other methods are available, too.  Doing something similar to existing
studies will provide the most comparative data, though existing
studies may have problems.


Analyzing the data not only provides numerous options but often
vigorous disagreement as to which is the best.  Try using multiple
methods; if there's agreement, that's a good sign.

--
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"

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