Cladistics and "Eclecticism"

[P.Hovenkamp]

At 10:26 AM 2/8/02 -0500, Thomas DiBenedetto wrote:
>-----Original Message-----
>From: P.Hovenkamp
>As I understand it now, in your view the existence of species is dependent
>on the success of the colonizers "in any real sense". What I wonder about
>is how this can be made into an exact distinction (sorry - if you don't see
>any use for exactness, you'd better withdraw from this thread). How much
>success is required? How viable must the new lineage be?
>***********
>The lineage branch would have to be viable long enough for a systematist to
>discover it (to recognize it as a taxon). If it isn't, then it will join the
>big set of extinct lineage branches that are forever lost to history.
>*********

I think that this is an important (and essential) extension of your concept
of what a species is.
In an earlier post you wrote:
"The criterion we use to delineate groups are the relationships that we
infer to
exist between the indiviuals in the groups, and between the groups
themsleves.  Although we necessarily use characters as evidence of these
relationships, it is the relationships that are the ultimate criterion."

 From what you now say, I conclude that the "ultimate criterion" must (with
emphasis: **must**) be conjoined with additional criteria in order to
delimit a species. I also conclude that this additional information comes
down to observable characters (of whatever kind) which allow systematists
to recognize something as a taxon.
Without this extra criterion, the example shows that we would be left with
a multitude of species, most of which totally irrelevant to systematics.

What it comes down to is that although the original Hennigian species
concept (lineages between branching points) provides us with an unarbitrary
way to delimit units in the fabric of life, it does not give us in fact
species, merely units that can be building blocks for species. The species
we all know and love are composed of these units - but the units are not
species.

>  If a short-term
>lineage is established, does that permanently split the fabric of the
>species? Did any lineages "back-speciate" when the Dodo went extinct?
>**************
>No, because we have evidence of the Dodo - like extinct species known only
>from fossils, they can be discovered even when extinct.
>We will never know about millions of the short-term lineages that died out
>without a trace. But if we do have evidence of one, then it should be
>recognized in its proper place.

We also have evidence of the crashed airplane population - that is not the
point. The point is now that the Dodo had characters of its own - which the
group of airplane occupants probably did not have. Unless - we expand the
example by assuming that their body size distribution just happened to be
significantly different from that of the surviving humans (and
statistically, we may suppose that happens in 5 % of all crashes)...

>AND - Hot off the presses:
>Tom:
> >"As a corporal level soldier, Jensen no longer exists. He is obsolent,
> >invalid". I suppose it is technically correct in a sense, but it doesn't
> >sound like a very good way to communicate meaning.
>PH:
>I don't see this as a very appropriate example.
>I am an individual being called Peter Hovenkamp. I was called Peter
>Hovenkamp as a boy, and after I was promoted to adulthood, I was still
>called Peter Hovenkamp. So far, so good. But after I'm deceased, there will
>only be my two sons, Jan Hovenkamp and Pieter Hovenkamp. Is there any sense
>to a system in which they should also be called "Peter Hovenkamp"?
>**************
>Geez Peter, gimme a break. Is is not an _example_it was an _analogy_.

Sorry - I should have used the word analogy. I still think it is not a very
appropriate one.

>Analogies, by definition, have elements that parallel the topic under
>discussion, elements that can be pointed to in order to illustrate the point
>that one wishes to make. They also necessarly have elements that are
>different and are to be ignored because they are not relevant to the point.
>I am aware that military organizational hierarchies are of a different type
>than internested taxanomic hierarchies - but those differences are not
>relevant to my point. In fact, given the differences between the two types
>of hierarchy, it is far more rational to speak about the extinction of
>corporal Jensen than it is to speak of the extinction of a lineage that has
>diverged.
>Now I will give you a chance to make these charges against me, by pointing
>out that your example/analogy is bad as well. Your name applies to you, and
>then you die. Taxon names apply to taxa which, in our example, diverge, they
>do not die.
That is exactly why your analogy was not very illuminating.

I die, but some of my chromosomes live on...

>I would also point out, just for fun, that if you lived in Iceland, for
>example, your sons would be called Jan and Pieter Peterson. Now that is a
>mature culture in touch with "Nature"!  :)

Just consider what would happen to the Icelandic registration system if
they should hear of phylocode...

Peter Hovenkamp