[Taxacom] Evolutionary misconceptions (was:Ladderisingphylogenetic trees)

[Richard Zander]

Regarding death, it's a powerful driver of altruism, particularly of
philanthropy and the crafting of legacies. Death is good, only not now,
oh lord.

Regarding extinctions, one of the major problems with molecular analyses
as inferential of lineage continuity and splitting, I think, is the
effect of ancient paraphyly. Paraphyly is common. Suppose a taxon is
molecularly paraphyletic and two new lineages pup off an ancestor. You
get a basal sister group of the ancestor A, then two molecular lineages
of B and C, the last sister with the ancestor A again: . . . (A (B
(C,A))) Suppose the basal A population dies out. You get the molecular
cladogram (B (C,A)). But suppose the terminal A population dies out. You
get (A (B,C). Two different molecular cladograms depending on extinction
of elements of ancient paraphyly. 

Now suppose about 50% of all species were paraphyletic (as one
researcher estimated), and half of those had two or more species budding
off to molecularly isolate one of the paraphyletic elements from the
other. This means 25% of all branches in a molecular cladogram should be
switched with either the next more basal or the next more terminal. This
is an important null hypothesis that should be examined and rejected if
possible, given the plethora of paraphyletic groups uncovered by modern
molecular studies. No rejecting the null doesn't make it right but only
rejection will support certain outrageous differences between molecular
and traditional classifications.

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of David Wagner
Sent: Thursday, March 11, 2010 9:36 PM
To: Jim Croft
Cc: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Evolutionary misconceptions
(was:Ladderisingphylogenetic trees)