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Re: RATITES AND BROODING



In a message dated 3/8/99 3:34:06 PM, m_troutman@hotmail.com writes:

<< Tom Hopp wrote: Yep. I can hardly wait for the more-thorough molecular data
which will nail down every bird's relation with every other without ambiguity
(I'm not kidding).>>

(Maniacal laughter ensues)  Not kidding?  Thanks, the best one I heard in a
while ;-)  Anyway, as most people who keep track of avian phylogenies
throughout the years (from Linneus, to Illiger, to Huxley, to Gadow-
Furbringer-Beddard, to Wetmore, to Verheyen, to Wetmore (again), to Cracraft,
to Olson, to Sibley and Ahlquist (twice), to 
Mindell and the various workers today) can tell you, there will probably
never, EVER, be an unambiguous avian phylogeny whether based on molecules,
morphology, whatever.  >>

Sorry to hear of your pessimism. The early molecular approaches were rather
primitive, and it is not until highly detailed sequence work is done on
rapidly evolving genes (like my work on mammalian alpha-lactalbumins) that one
can get really fine discrimination, not just between species, but WITHIN
species (refer to histocompatibility and immunoglobulin genes if you want
overkill). Early work was done on such immutable genes as cytochromes c, which
are useful for giving simple and easily interpretable phylogenies, but just as
they are simple, so too are they low-resolution, lumping whole clades into a
single point. Not so with immunoglobulins and such. The problem there has been
that heterogeneity made it nearly impossible to sort out all the sequences and
different alleles that were needed to draw a phylogenetic relationship out of
the mess. But DO hold your breath. Techniques get more sophisticated and
cheaper every year. Soon even MUSEUMS will be able to afford to do this kind
of work. Then look out, because the answers will ALL be FORTHCOMING. Believe
it or don't, at your peril.
    You really ought to do something about that laugh.  ;^)
    Tom Hopp