Re: How are columbiformes (doves and pigeons) related topsittaciformes?

["Dora Smith" <villandra@austin.rr.com>]

Christopher:

I am wondering if method of statistical analysis could be contributing to
this difficulty in resolving the main direction of bird evolution - if it
was backwards (passeriformes) or forward (from primitive birds).

If I were going to do a project of this sort, I would look chart differences
in genetic coding - and leave it at that.

My own background is all but degree at the Masters' level in social science,
with an associates' in science.   I concentrated on biology and chemistry in
my first two years of college, and studied alot of statistics in graduate
school.

Some people are doing statistical methodologies that I don't follow at all,
and some are reporting log odds ratios and appearing to use them as
regression coefficients, which suggests they are doing log linear analysis
in an effort to demonstrate that their findings achieve statistical
significance.

That requires that one form hypotheses about directionality of what came
before what or caused what - and there are any number of ways that
regression coefficients or log odds ratios could cause two phenemenon that
are related to have backwards directionality or spurious directionality.

Statistical significance is nice, but it will never beat logic.  I would
really just construct tables showing the actual genetic changes across bird
orders and leave it at that.   Common sense tells you that there will be
fewer genetic differences between closely related species, and more genetic
differences between distantly related species, and that some genetic trait
should be common to all of them.    One ought to be able to follow the
accumuluating differences to what birds have been around longest, if indeed
any of them have.  ...  Oh well, don't make me go through and get the genes
from Genbank or wherever and do it!

If genes have evolved in parallel ways through convergence, then one ought
to be able to demonstrate why that would happen by pointing out what the
gene does that is so strongly adaptive that it would evolve independently
more than once.   In the articles I have read, of which there are maybe ten,
noone has discussed what a single piece of the genetic code they examine
actually does!

Would mitochondrial DNA in particular be likely to evolve independently in
similar ways through convergence?    It kind of seems unlikely - unless it
had something to do with the energy needs of the animal in question!
Could birds do the whole oxygen and metabolic thing so differently that they
need different mitochondria to do it?

Anyhow, exactly what method of statistical analysis did you use to arrive at
your conclusion that passeriformes are basal to birds?

Yours,
Dora Smith
Austin, Texas
villandra@austin.rr.com
----- Original Message -----
From: "Christopher Taylor" <ck.taylor@auckland.ac.nz>
To: <dinosaur@usc.edu>
Sent: Monday, May 10, 2004 5:57 PM
Subject: Re: How are columbiformes (doves and pigeons) related
topsittaciformes?


>     Interestingly enough, I did a project for an MSc paper a few years
back,
> where I attempted to construct a phylogeny of Aves using 12S and 16S rDNA
to
> test the monophyly or otherwise of Pelecaniformes. The final tree was
almost
> totally unresolved, but one of the very few well-supported clades which
did
> appear was Psittacidae + Coliidae. Unfortunately, it wasn't the main focus
> of my project, so I didn't look at it further. (I also found strong
support
> for Passeriformes basal to Neoaves - you have been warned.)