Whooper; Canadian geese split; paraphyly.
kinman2 at YAHOO.COM
Wed Nov 17 10:04:20 CST 2004
I am a non-strict cladist, and I am concerned with clades too (very much so). But our insight into the branching patterns for some groups (reptiles) will always be severely impaired (lack of fossils, and piecemeal even when we do have them). Those are the places in the tree of life where a bit of formal paraphyly can be our friend (and complete cladification our worst enemy). We can slowly improve the internal cladification of groups like Class Reptilia, but the complete cladification of the Tree of Life is wrong-headed---as is its resulting radical attacks on every perceived paraphyletic group and the total abandonment of taxonomic ranks (ranks are human constructs, but very useful ones).
As for the barnacle goose, we have to be careful to root the cladistic analyses properly. It seems to me just as likely that populations of barnacle geese gave rise to cackling geese, populations of the latter gave rise to large-bodied Canada geese (and they gave rise to the nene goose)-----a series of single paraphylies, with barnacle geese as more primitive (not derived). Relying too heavily on mitochondrial genes can be cladistically risky. And trying to raise a generation of strict cladists that are taught that paraphyly is bad or unnatural, well, that's just plain horrifying (even without a phylocode to institutionalize it even further). I am pro-cladist, just anti-strict-cladist. I am for as much holophyly as we can discover, but definitions and codes cannot make paraphyly go away (and strict cladists are ignoring and/or attacking a very useful concept and classificatory tool).
------ Ken Kinman
Thomas Pape wrote:
Ken: Strict cladists are concerned with clades, and rank is a human construct.
Paraphyly is comparable to insufficient knowledge and it is challenging mainly for this reason. As we just heard from Laurent Raty, the Barnacle Goose appears to make the unsplit Canada Goose twice paraphyletic. Again, our growing insight into the process of evolution stems from the definition of clades and the branching pattern they form.
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