Dear Fellow "Bird Nerds",

        After reading this and the Re: to it, I grabbed a copy of "Phylogeny and
Classification of Birds: A Study in Molecular Evolution" by Charles G. Sibley
and Jon E. Ahlquist (1990).  The study used DNA-DNA hybridization to establish
phylogenetic trees, which used DNA from the entire genome of the species, not
just a portion of the DNA.  Jon Ahlquist was always very fond of saying, "Why
would you just want to use a few genes when you can use the whole genome?"  His
point being, "Knowing part of the story can be very misleading compared to
knowing the entire story."  According to the figure included with the article
Bill linked to this new study uses just 19 loci (19 genes).  I do not have the
background needed to answer Jon's question:  Are the findings of this study
using 19 loci more accurate then the findings of Sibley and Ahlquist using
DNA-DNA hybridization of the whole genome?

        In Figures 355 and 356 on pages 840 and 841 of Sibley and Ahlquist the Parrots
are "on page 840", as significant distance from the Falcons, Hawks and Eagles,
which are clustered together, "on page 841".  Before there were DNA analyses
there were analyses using the characters of organisms (mostly morphological
structures) and cladistic methods to evaluate phylogenetic relationships based
on shared, derived characteristics.  To my knowledge none of the phylogenetic
studies based on shared derived characteristics placed Parrots and Falcons
close together, saying they are closely related.  I know the Sibley and
Ahlquist findings for the most part confirmed the cladistic analyses that
preceded them, and that some of the "controversial" finding they had, such as
the idea that New World Vultures are related to Storks, had been proposed by
other before Sibley and Ahlquist, based on analyses of morphological
characteristics of the two groups.  What also came before DNA studies were
proteins studies, using the structure of the proteins (a direct product of the
DNA) to study relatedness.  Again, I never heard of a protein study suggesting
a close evolutionary relationship between Parrots and Falcons, and that Falcons
are not clustered with Hawks and Eagles.

        One might ask, "Why should you expect the morphology and the DNA to tell the
same or very nearly the same story?"  Well, the morphology of the organisms is
based on the proteins that are produced in the organism, including (perhaps
especially!) the regulatory proteins that stimulate, inhibit and time the
developmental changes in the organism.  Those regulatory proteins attach to DNA
to stimulate (or inhibit) the gene's production of proteins.  The structure and
function of the proteins depends on the DNA they are produced from.  What these
results seem to suggest, in part, is that very similar DNA would produce very
similar proteins and that these very similar proteins would then produce birds
with radically different morphologies.  There is something about that scenario
that just plain doesn't make sense!  Another implicit implication is that
somebody is horribly wrong; Either "you" with the new results or "them" with
the old results.  It is not that often that different data for the same study
subject disagree this sharply!

Best wishes and good birding!

Steve Edinger





--On Friday, June 27, 2008 8:45 AM -0400 Bill Whan <[log in to unmask]>
wrote:

> I read about an interesting story in the Chicago Tribune, available at
> http://www.chicagotribune.com/features/lifestyle/green/chi-birds-web-jun27,0,
> 7133429.story
>
>         One of the items involves taxonomic studies that suggest falcons are
> more closely related to parrots than to hawks & other raptors. I was
> reminded of a conversation we had on this list trying to identify the
> species of bird represented in a Hopewell effigy: some of were sure it
> was a Carolina parakeet, and the establishment was betting on peregrine
> falcon. Might not be such a big disagreement after all.
>         The Tribune story mentions this in the course of describing some major
> realignments in bird taxonomy, to be announced soon in Science magazine.
> A quote from AOU Checklist Committee member Carla Cicero was intriguing
> as well. The Committee will publish changes in the official North
> American list in a few weeks, and Cicero is quoted as saying, "There are
> going to be a lot of changes, I can tell you that."
>         As in years past, I'll pass along a summary of these decisions to
> ohio-birds, so we can trash our checklists all over again.
> Bill Whan
> Columbus
>
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***********************************************************************
"The hypothesis we accept ought to explain phenomena which we have
observed. But they ought to do more than this: our hypotheses ought to
foretell phenomena which have not yet been observed.'
-- William Whewell (1794-1866) English mathematician, philosopher

"Taken over the centuries, scientific ideas have exerted a force on our
civilization fully as great as the more tangible practical applications
of scientific research."
-- I. Bernard Cohen (1914- ) U. S. historian of science

"There is no adequate defense, except stupidity, against the impact of
a new idea."
-- Percy Williams Bridgman (1882-1961) U. S. physicist, Nobel Prize, 1946

"Nothing in biology makes sense except in the light of evolution."
-- Theodosius Dobzhansky, 1973
***********************************************************************


---------------------------------------------------------------------------
Steven A. Edinger, Physiology Lab Instructor

064 Irvine Hall
Department of Biological Sciences               [log in to unmask]
Ohio University                                 Office:  (740) 593-9484
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