Locality data

Nhu Nguyen xerantheum@gmail.com
Wed, 31 Oct 2012 10:54:17 PDT
> Jim Shields wrote: " the DNA sequence of the organism IS the organism, so
> the DNA sequence perforce defines the species. "
Jim, this is so true. I work with DNA or organisms that are not often seen
by the naked eyes and there are countless number of species that are only
known by their DNA. We know nothing about the organism except for where the
DNA was collected (which is often in a core of soil).  Your comment is
especially true these days when information about organisms are connected
through the web and if we can find DNA for it on a public database like
GenBank, we know that it exists. DNA is the only universal identifier of an
organism that does not require expertise in a taxonomic group. If I want to
know what species of snail eats my bulbs, I can just sequence it without
needing to contact a snail expert. I'm simplifying things here. There is
still a lot we need to work out. We've only been applying DNA to identify
organisms for about 20 years. We've got a long way to go to make things
good enough for everyone to be able to use.

Jim Mc:

> "DNA sequences do not define species; rather, they are a consequence of
> the existence of species"
You can switch it around by saying "species are a consequence of DNA" and
it would still be valid.

> Isn't that another way of saying that  taxonomy is good at recognizing
> entities which have practical purposes?
Apart of the inherent inclination of humans to organize the natural word,
taxonomy produces products (=names) that we all can use to exchange
information. There is nothing wrong with viewing taxonomy as a practical
tool for the end user.

> That some forms of life do not seem to fit into the biological species
> concept is not a shortcoming of the concept, it simply indicates that not
> all forms of life exist as species.
I see it differently. If a concept does not apply to all living organisms
equally, it certainly IS a shortcoming. And it is true that perhaps not all
forms of life exist as a species, but as a gradient that goes from one
point to the next.


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