Cladistics and "Eclecticism"

Thomas DiBenedetto tdib at OCEANCONSERVANCY.ORG
Thu Feb 7 09:24:34 CST 2002

-----Original Message-----
From: Hubert Turner

       |   |--B
    |  |------C

 ...  why say that taxon Z (or Y, or X) now is no longer a species, but
rather a clade?
It seems rather obvious to me that Z refers to the entire group that
contains the terminals A,B,C, and D. How can Z be considered a species? Is
Primates a species? At one point in time Z was a species level taxon, but
evolution has happened in the interim.
To me this looks like using the name Z  at the species level first, and
subsequently (after a splitting event took place) at a higher taxonomic
Well, yeah obviously,,,,Is this not what happens in the real world? When a
new taxon comes into existence at a speciation event, the new taxon is a
terminal lineage branch, a species. If it subsequently diverges, it
encompasses more than one species, it is a non-terminal branch, i.e. a
higher level in the hierarchy of life. Is this not obvious?
 To me it makes more sense to speak of the branch between the splitting off
of species D and the splitting off of species C as "species Y", but of the
same branch together with all its descendant branches (C, X, A, and B) as
"clade Y".
Yes of course. I dont see that this is inconsistent with what I said above.
At the beginning of the evolution of this system you had one taxon, species
Z. Then Z diverged (evolved), and became a higher taxon, with two new
terminal branches, D, and Y. At that point in time, both D and Y were
species level taxa. So the branch between the splitting off of D and C was a
species, Y. When C branched off, Y became more complex, a higher taxon, or a
clade as you say.  At first this clade encompassed the branch that had been
species level taxon Y plus the new terminal, C, plus the other terminal, X.
By now the descendants of the original species Y have even further diverged,
so clade Y (higher taxon Y) now encompasses all that you say it does. I dont
see that we disagree, do we?
After all, the branch was at one time a proper species,
Yes of course.
which ended (went 'extinct' >as a species<; of course the lineage itself did
not go extinct) when it split in two.
Grrrrr. Why oh why do y'all constantly talk about these things ENDING, or
going extinct? What do you mean "ending as a species"? "Species" is just a
rank, at least in systematics. The lineage evolves, the rank changes, thats
all. It seems to me to do nothing but add to confusion to talk about species

Tom DiBenedetto

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