Ah but you could use the arbitrary primer method to create a "genetic
finger print" and using the same set of primers with closely related
organisms look for conserved regions of dna for sequenceing and further
investigation. This method is being widely used in the area of insect
evolution and ecology work to see via the "genetic finger print" if two
look alikes ( simmilar morphology, but different ecology or behavior)
actually have a genetic basis for these differences. I think this sort of
work has been done extensively with mycoplasma-like organinsms where
morphology really can't be studied and you want to find out if the causal
agent for cherry buckskin is the same as X disease or witches broom of
pears. I suppose it is easier to say that it a given sample is the same
rathern than different. Alternatively, for certain groups we know that
there are highly conserved DNA sequences, that the region between these
points could be amplified or the conserved region could be amplified via
PCR and sequenced to look for small changes in these conserved region. I
guess I was over simplifying by using a OJ Simpsion generic PCR ;-).
MTF
While all DNA has the same structure, not all DNA
>is alike. Very basically you have two "types", coding and non-coding.
>Coding regions contain genes, non-coding regions don't appear to do
>anything, (though it is not really well understood from any perspective)
>and is often called junk DNA. Junk DNA, because it doesn't code for
>anything has a much higher apparent mutation rate, hence differences
>between populations can evolve much faster. This makes it excellent for
>population studies looking at variation within species. It is not
>typically used for seperating species. To complicate matters more there
>are several structures in cells that contain DNA, each having it's own
>characteristics and peculiarities. Deping upon what question one is
>asking depends upon which DNA they examine. Arguably the most commonly
>used is mtDNA (mitochondrial DNA) as it is maternally inherited (you only
>get your mother's copy) meaning it does not experience recombination.
>This makes it excellent for studying the history of populations and
>species (mostly for phylogenetic reconstruction). It is also good for
>seperating species. There are many other variations on this theme that I
>won't go into.
>
>The main thing to remember is the technique depends upon the question
>being asked and that the more different techniques one uses in the study
>the more reliable the outcome will be relative to reality (including both
>genetic and morphological techniques).
>
>Tootles
>Peter Unmack
Mach T. Fukada, Web Master
fukada at hawaii.edu
Honolulu Aquarium Society
http://www.geocities.com/Heartland/Meadows/2948/HASF.html