Subject: (no subject)
Date: Dec 1 11:16:42 1994
From: Nie'er tongzhi - njf7i at kelvin.seas.virginia.edu


To Dave Wright and all who are interested,
In resoponse to Dave Wright's interesting posting on taxonomy and
the species concept, I pose a couple of a little bit off
the subject questions.
Question 1: What is meant by a "monophyletic group" ? What about "Clade" ?
Question 2: The original definition of species, I believe, regards the
ability to produce viable offspring. Two populations were considered to
be of the same species if they could mate and spawn fertile offspring.
A prime example of different species were the horse and donkey,
who could only produce a mule, which was generally incabable of further
proliferation. A more recent definition of species (correct me if I am wrong)
which is weaker than this originial definition in allowing for production of
fertile offspring between different species is as follows:
Population A and population B are defined to be of different
species provided that when allowed to interbreed for an INFINITE
amount of time, there will still remain in the existing mixed population
5 percent pure A types and 5% pure B types. So for example, the red-shafted
and yellow-shafted flicker, assuming that they are in fact the same species
of bird, if thrown together and allowed to go at it for a zillion years or so,
will produce a resultant population of birds which exhibit a full spectrum,
or continuum, of different shades of flicker ranging from yellow to red,
thus swamping the gene pool,
and most impotantly the percentage of the population which is pure yellow
is less than 5 percent. Likewise for the percentage of pure red-shafteds.
Where does this 5.0 percent come from ? Is this figure arbitrarily set by a
committee, or does it arise from a biological principle as some type of
mathematical limit ?
Question 2: Does the new DNA hybridization technique of species
determination correspond to the above (5 percent) definition ?
In other words, has it actually been verified that if two populations
are identified as different species according to DNA hybridization, then
the two populations when allowed to breed at random for an infinte
amount of time, will definitely leave 5 percent pure parent populations ?
Question 3: Do plants fit into the same definition ?

Mr. Wright's discussion is a bit over my head, as I do not have any
biology training, although the subject of the species concept is
fascinating, and leaves many unanswered questions of me.
Perhaps I missed the theme of the posting altogether.
Maybe it refers not to speciation, but to the concept of rank
in its heierarchy of species, genera, family, order, etc.
In any case, I feel that we are now entering the golden age of bird
taxonomy with the invent of interpheresis and DNA hybridization techniques.
The subject leaves many unanswered questions in my mind.


Neil J. Fergusson ******************
1405 1/2 NE 56th St. * Baffins *
Seattle, WA 98105 * or *
(206) 517-5466 * bust *
njf7i at kelvin.seas.virginia.edu ******************