[Taxacom] Paraphyly/predictivity

Richard Zander Richard.Zander at mobot.org
Sat Mar 28 14:01:08 CDT 2009

One of the points I've made in the past is that some changes made in phylogenetic classifications are warranted by new information about evolution or by well-supported corrections to previous wrong classifications, AND some other changes are due solely to enforcing classification by holophyly, which in my opinion suppresses information on ancestor-descendant relationships as reflected in classification by appropriate flagging with higher rank. Thus, distinguishing which changes reflect fully what we think we know about evolution and which changes reflect only what sister-group analysis reveals about evolution will busy future taxonomists when they should be doing other things.

If the Epacridaceae turned out to be essentially the same as Ericaceae (same diagnosis) then, hey, great. If on the other hand Epacridaceae was an autophyletic taxon with significant evolutionary features distinguishing it from the Ericaceae, then not okay. The problem here is, as usual, that we don't know from just the lumping WHY the two were lumped, but the latter reason, if suspected, means that the Ericaceae in Australia might be of two rather different evolutionary groups based on expressed traits. What would an ecologist or evolutionist feel about loss of this information? Possibly nothing because people in other fields have not been warned that phylogenetic classification is for phylogeneticists. Doubtless the answer is in the literature, but a classification should be a précis of what we know about basic taxonomic units and evolutionary groupings of them. 

Richard H. Zander 
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-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Peter Stevens
Sent: Saturday, March 28, 2009 1:06 PM
To: Mike Dallwitz
Subject: [Taxacom] Paraphyly/predictivity
When I  was working on my thesis, it was a matter of some interest that  Ericaceae (the rhododendron/blueberry/heather family) were so poorly represented in Australia - except that it has turned out that they  are very well represented there, but we were calling them  Epacridaceae then, and so we thought that they were irrelevant when  thinking about the distribution of Ericaceae...

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