Re: Hierarchal vs Non-Hierarchal Interfaces to Biological Taxonomy

Marshall wrote:

> On Dec 22, 1:17 pm, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
>

>>Larry Coon wrote:
>>
>>>Bob Badour wrote:
>>
>>>>Which common bird is it that has three cohorts A, B and C where A and B
>>>>can interbreed, B and C can interbreed but A and C cannot? Is it the robin?
>>
>>>There's lots of species like that -- it's called a ring
>>>species.  I think it's the salamander where every subspecies
>>>but two can interbreed.
>>
>>>An interesting question is when you have subspecies A, B & C,
>>>where A & C cannot interbreed, and B goes extinct, do you now
>>>have two distinct species?
>>
>>Which opens the floor to: "How many species did you have
>>before B went extinct?"

Here's an even better one: Suppose a retrovirus comes along that conveys some fitness advantage so that it becomes ubiquitous among a species: ducks for instance. Suppose as well that the virus crosses over from the domesticated duck population into pigs and humans where it too becomes ubiquitous.

At that point, humans, ducks and pigs all share a unique recent ancestor. Where does that put us in the taxonomy with ducks and pigs?

> Other things that are abstractions: the
> number 3, the concept of being alive,
> the gender partition with its two equivalence
> classes, male and female, the seasons,
> etc. Most any idea with sharp edges to
> it is an abstraction; the natural world
> is much more fine grained.

Not only fine-grained but complex too. When one designs something, one generally must control the locus of effect or the design becomes unworkable. That's a total non-issue for evolution and for biological systems. Proteins, enzymes and hormones get reused for almost endless unrelated functions.

  (I am tempted
> to say "analog" but when you get down to
> a low enough level, it looks digital again.)

True enough. 1) Digital, 2) highly redundant, and 3) tolerant of partial failure. Received on Sat Dec 23 2006 - 01:01:01 CET