Strange Question - electrophoresis
Stelenes at aol.com
Stelenes at aol.com
Thu Jul 22 02:52:58 EDT 1999
Though DNA is a nice ace to have up the sleeve to make gross statements like
X is relatively closer to Y than it is to Z, I think it is to taxonomy what
computers were to accounting. I.e., if you don't figure out what you are
looking for without relying on the "system", you are may not be doing more
than wasting your time. In plants, typically markers, or uniquely conserved
sequences of DNA not found in other organisms, are used to define varieties
of a species of plant. But a new plant variety can be the identical thing as
the old variety except with the addition of the marker sequence for Fusarium
resistance or whatever.
All I hope to illustrate with the above is that in the case of plants,
varieties are nearly arbitrarily defined to reflect premeditated or human
centric selection criteria identified to the detail of the DNA.
But that will do little to answer the theological question as to whether two
things are the same subspecies or not which nature has let evolved proudly
into whatever they now are. The species thing is also a somewhat arbitrary
human construct. Mind you I don't mean to imply that traditional taxonomy
can do much better, but it requires more thought in the absence of reliance
on statistics. You can pick the set (fingerprint) of markers yourself which
you can define to uniquely define a subspecies, but then again by appropriate
selections of markers you probably could find a "same" and a "not same"
answer in a subjective manner for the comparison of the two individuals' DNA.
So back to traditional taxonomy...with a little modern help...
The chimp having 2% different doesn't really mean much when it comes to
separating our human species from chimps. So if birds had 5% difference does
it strengthen the case that humans are closer to chimps? Suppose all the 5%
is unused DNA? Then the phenotype would be not different and this newsgroup
might be for the birds and we flying. Or suppose gorillas had 1% difference
from humans but it was all in the diet and reproduction traits, so they only
ate bananas and had bent genitalia compared to being omnivores with straight
organs. (I picked those examples in parallel to host plant differences and
genitalia differences, two favorite ways to separate species and subspecies,
to try to stay on the Leps topic)
Try telling someone in the GMO debate that just because the organism is
99.9999999% the same DNA with the tiny weenie modification, that it is the
same species. You more likely would be force fed the mutant.
My opinion is that more information is definitely better than less and can
help make overall assessments, but since speciation is not linear, getting
caught up too much in relying on genes could cause oversight of the
traditional painfully difficult taxonomy which tends to be more intuitive.
In cases where speciation is linear, the question is more likely not to be of
differentiating subspecies, but of checking for a common ancestor.
Well sorry for rambling on in response to your invitation on this and related
In a message dated 7/21/99 2:11:52 PM Pacific Daylight Time,
Norbert.Kondla at gems3.gov.bc.ca writes:
> At first glance this question may not seem to be relevant to leps but bear
> with me - it is. some time over the past 2 years somebody mentioned to me
> that there is only a 2 % genetic difference between humans and chimpanzees.
> I would be eternally grateful if any of you can provide me with a citation
> of a publication for this observation - assuming this was published
> somewhere. The lep connection of course is that I am in the process of
> trying to decide how much weight to place on chemical differences in
> as an aid to deciding on species vs subspecies status. As everything else,
> I have heard differing opinions on this subject - and I find it useful to
> hear differing opinions before deciding what my own opinion will be. Even
> not directly relevant to the human/chimp situation; please feel welcome to
> hold forth on the topic of electrophoresis/chemistry in taxonomy or give me
> a shout directly if you prefer.
> Norbert Kondla P.Biol., RPBio.
> Forest Ecosystem Specialist, Ministry of Environment
> 845 Columbia Avenue, Castlegar, British Columbia V1N 1H3
> Phone 250-365-8610
> Mailto:Norbert.Kondla at gems3.gov.bc.ca
More information about the Leps-l