[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Cladism (akin to masochism)

jpoling@magnus.acs.ohio-state.edu (Jeff Poling) wrote: 
 Regarding Cladism (akin to masochism)

>   With the recent discussion stemming from a problem I've been having
>assigning phylogenic groupings, it suddenly occurred to me that the
>groupings I've been using are no longer appropriate.

  Well, some Linnaean names *were* adopted by cladists. Many other names never
caught their fancy.  Cladists sometimes "fudge" a little and take Linnaean 
names and alter them slightly.....to avoid confusion with Linnaean rankings, you
see.  Therefore, "Reptilia" means one thing to a Linnaean-ophile, but it means
something slightly different to a cladist. 

>   Are the terms Class, Order, Infraorder, etc. used in the clade world?

  The *RANKINGS* are not used, but the NAMES within those rankings might
be used.  Thoroughly confused yet?  "Subclass Dinosauria" isn't a clade 
name....but "dinosauromorpha" IS a clade.  "Theropoda" is used in both
Linnaean systematics, and in cladistics.  But not all clade names have a
Linnaean counterpart.  Sigh...wish it were so, but it "ain't". 
The reason that Linnaean rankings are not used _sensu stricto_ 
is because cladistics infers things about rankings that are 
entirely different from what ol' Carl Linnaeus had originally intended. 
Keep in mind that all that Linnaeus wanted to do was "name" things.
Cladists not only want to name things, but they want to make INFERRENCES
about why they are named the way they are. 
Everything within a clade has a common ancestor.  And that ancestor is part
of another group that has a common ancestor, too.  So the INFERRENCE made in
cladistics is...ahem...cough...evolution.   Linnaean systematics doesn't
deal with evolution. (although I have faith that Carl, had he 
been alive in 1986 when Gauthier used cladistics on birds and other
reptiles, would have taken to it nicely...I'm sure Carl was a reasonable
man!   :-) 

 Many of today's sytematicists don't like cladistics because cladists 
invent new names and remove old names at the drop of a hat (clade inflation!).
Linnaean people like a tidier, more stable system of nomenclature. That's
what some of the squabbling is about. The remainder of the squabbling
centers around the cladist's choice of criteria to define a clade. 

>   And as long as I'm at it, is every line attached to a specific named node
>carry that name?

  In cladistics, the named nodes (places where different groups
"branch-out") always define whatever is above it on the tree.  We are all
members of "nested clades" (sort of a comforting thought!).