[Taxacom] Evolutionary misconceptions (was: Ladderising phylogenetic trees)

[Kenneth Kinman]

Hi Curtis,
     Of course, if a student (or misinformed professional) claims that
there are contemporaneous tracks of humans and Mesozoic dinosaurs, we
obviously should brand that as a misconception (or in some cases even an
outright deception).     
       What I am talking about is more subtle and debatable---whether
there is actually a clear distinction between cladogenesis and
anagenesis (however they are defined) or if there is a continuum of
types that are really neither one nor the other.  As Richard noted, true
cladogenic speciation cannot occur without further anagenesis (which
then sometimes results in a subspecies evolving into a full species).             
      But what really concerns me the most are very asymmetic "splits",
the most extreme occurence probably being a single pregnant female being
isolated in a new isolated habitat (like an island).  The new population
obviously will be just a new subspecies until further anagenesis results
in reproductive isolation which exceeds mere geographic isolation.            
        When such reproductive isolation does finally evolve, is it the
result of cladogenesis or anagenesis?  Or is it really both?  And if you
are tempted to answer that the cladogenesis came first, can we know how
much anagenesis had actually previously occurred in the particular
mainland population which gave rise to the island population.    
       My point is that the typical cladogram showing the difference
between anagenesis and cladogenesis is rather simplistic, and there are
any number of different combinations between gradual anagensis, sudden
anagensis, and various forms of cladogenesis.  I am doubtful that Laura
appreciates such subtleties.  She is a psychologist, and I am frankly
doubtful than even a lot of trained biologists really understand such
subtle and complex biological concepts.        
      On the other hand, although some of the students she claims have
misconceptions may indeed have them (as you noted), but some of the
students she claims have misconceptions may actually have more insight
that she has, and in my opinion some of them may far be less subject to
tautology than she is.  The students she studies presumably represent a
broad continuum of intelligence (and dare I say it, of intuition).  As a
psychologist, I doubt that she has the insight of some biology students
with more biological training and insights.  Again, I suggest that it is
more likely that the she may have misconceptions that she needs to
acknowledge, and at least some of the students she accuses of having
misconceptions perhaps really have more insight than she does.     
      Likewise, I would not assume that all students (especially college
biology majors) have modern monkeys in mind when they say that apes (and
thus humans) evolved from "monkeys".  Perhaps some of them just a have a
more intuitive understanding that mother-daughter species are just as
important to evolution as the less asymmetic sister-sister splits that
Hennig emphasized.  Criticizing them may be the equivalent of
criticizing Einstein for disagreeing with students of mere Newtonian
physics.  The subtleties and differences are only become obvious decades
later.  In my opinion, stict cladism is in some ways at the Newtonian
stage (and therefore in some ways less helpful, and perhaps even
counterproductive).
         --------Ken Kinman
------------------------------------------------

Curtis Clark wrote:

On 3/9/2010 7:59 PM, Kenneth Kinman wrote: 
> Hi Curtis, 
>         I don't think that is what she meant, given that >she make the 
> broad statement that: "There is no evidence to support >anagenesis as
a 
> mechanism of speciation."  She seems to be dismissing the >idea of 
> anagenetic speciation, be it "bad" or "good". 

But in fact she is correct in that regard. I don't doubt the occurrence
of anagenesis (there are abundant examples both from living organisms
and from fossils), but I have yet to see evidence of anagenesis giving
rise to a new species without lineage-splitting. Of course, if species
are human constructs (which I reject, but it seems a majority of list
members support), and we define species as the result of cladogenesis,
then it is a tautology. 

>         What I really worry about are the students who she >might be 
> negatively influencing by branding their ideas as >misconceptions.
She 
> seems to be branding all anagenetic evolution as a >misconception
(just 
> as strict phylogeneticists brand all formal paraphyletic >taxa as 
> unnatural and/or "unscientific"). 

So if a student says that the existence of contemporaneous dinosaur and
human tracks in Texas supports a recent creation of the Earth, we harm
that student by branding it a misconception? I don't think she's
branding anagenetic evolution as a misconception (I don't think she
addresses it), but rather anagenetic speciation. Inasmuch as anagenetic
speciation is largely (outside this list) regarded as a discredited idea
of the past, one has to draw the line somewhere. We all know where
"teaching the controversy" leads. 
> P.S.  As I noted earlier this year, I am not convinced >that "Humans
are 
> descended from monkeys" is a case of "bad" anagenesis. 

Students have a modern monkey species in mind (however ill-conceived it
might be) rather than a higher taxon. If I were instead to say "Humans
are descended from vertebrates", the students would not "personalize" it
so much.