Give me a day or two to mull this over and ask (hopefully an intelligent)
question.

Thanks for your response

K
"Ted Byers" wrote in message
. ..

"K Barrett" wrote in message
news:xGQUb.186854$sv6.989995@attbi_s52...
[snip]
How identical *is* species DNA anyway?


This question gets quite close to the real issue. If rephrased to be,
"Are
the genomes of two specimens of a given species identical," the answer
must
be no unless the two specimens represent clones of the same organism. The
reason for this is that either the genome possessed by a given individual
is
identical to that possessed by another organism of the same species or it
isn't. What both your question and my alteration of it presuppose we know
what a species is and how to determine whether or not two arbitrary
specimens are of the same species.

Given some idea of what a species is, however, a more useful question
would
be, "How similar are the genomes possessed by any two individuals of a
given
species likely to be?" That is, in fact, something that can be
quantified.
Only clones (including all products of asexual reproduction but including
also identical twins - the products of a natural cloning process if you
like) will have identical genetic material. Modern taxonomy is based on
measures of similarity, not judgements that two given specimens are
identical.

The more fundamental question, which must be answered FIRST, is "What is a
species?" Without an answer to that question, it is not possible to form
rational judgements on any other taxonomic issue. And there is no such
definition in widespread use by taxonomists and that is the primary reason
why modern taxonomy is in such a mess; much to the chagrin of other
biologists and of horticulturalists alike.

It is useful to observe that, among the cases of which I am aware, it only
takes tiny genetic differences, in terms of percentage of genes having
different alleles, to produce enormous differences in phenotype (the
consequence of gene expression). The genetic material possessed by the
Inuit (also known as eskimos - to the best of my knowledge, they prefer to
be called Inuit), Dene, african bushmen and indoeuropeans is so similar,
it
would be both difficult and tedious to measure the differences to an
acceptable degree of precision, and yet look at the diversity the existing
differences make in their respective phenotypes.

Does this help?

Cheers,

Ted