News from IAB

The mission of the International Association of Bryologists (IAB), as a society, is to strengthen bryology by encouraging interactions among all persons interested in byophytes.

Friday, October 9, 2009

RE: BRYONET: IAB blog : Are you with monphyly or are you with

paraphyly?
Date: Fri, 9 Oct 2009 13:03:38 -0500
From: "Richard Zander" <Richard.Zander@mobot.org>
To: <bryonet-l@mtu.edu>
Sender: owner-bryonet-l@mtu.edu
Precedence: list
Reply-To: bryonet-l

BRYONET

The IAB blog's question is now:
"Do species have to be monophyletic?"

Some problems with this. First, why just species? Also "have to be
monophyletic" is odd because many species just are paraphyletic, like
brown bear versus the autophyletic polar bear. Only later, after
recognition of paraphyletic status, do phylogeneticists wreak havoc on
classification.

Shouldn't the question be:

"Do taxa have to be
1. split into cryptic species if paraphyletic, or lumped into one huge
species with the autophyletic group, or

2. generously permitted to be recognized as a natural paraphyletic taxon
versus the autophyletic natural taxon.

I here repeat that recognition of paraphyletic groups will greatly
decrease the joss of phylogenetic analysis because the possibility of
extinct paraphyletic lineages makes the highly precise results of
molecular analysis doubtful. The chance of extinct paraphyletic lineages
can be judged from the percentage of extant paraphyletic lineages. Only
if paraphyletic lineages are verboten can phylogeneticists simply rename
all extinct lineages and so dispose of them administratively. One can
expect one or more extinct molecular lineages representing isolated
populations for every large taxon, and these lineages may be isolated
from the extant molecular lineage by one or more lineages of a
different, derived taxon. This is within any reasonable patristic
distance judged from phyletic constraint (frogs don't change into foxes
right away).

*****************************
Richard H. Zander
Voice: 314-577-0276
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166-0299 USA
richard.zander@mobot.org
Web sites: http://www.mobot.org/plantscience/resbot/
and http://www.mobot.org/plantscience/bfna/bfnamenu.htm
Non-post deliveries to:
Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110
*****************************
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