horizontal transfer and Bilateria (also was: Lucy in Newsweek)

[Ken Kinman]

Curtis,
     I would tend to agree with your statement.  And even among prokaryotes, I believe the primary flow of genomes is longitudinal (vertical).  This is in contrast with Carl Woese who now maintains that horizontal flow was so rampant in early prokaryotes that it has largely obliterated much of the broad traceable phylogeny.  I think this is probably wishful thinking because a less obliterated (more robust) prokaryotic phylogeny, such as that advocated by myself and Cavalier-Smith, would probably reflect badly on Woese's long-held beliefs and pronouncements (three urkingdoms, three domains, thermophilic origins, etc.).
     On the other hand, I also believe that we may be underestimating the potential of horizontal transfer in the evolution of Metazoa.  Even the bivalved shell, which I believe may have arisen only once in Metazoan evolution (in itself a very controversial viewpoint), may have actually been horizontally transferred by genes from a protist to a metazoan.  IN FACT, it would not surprise me if such an event could have even triggered the evolution of bilateral metazoans.  If so, this has profound ramifications for the evolution of all bilateral metazoans (not just molluscs and arthropods).  More on that in due time.
               -------- Ken Kinman
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From:  Curtis Clark <jcclark at CSUPOMONA.EDU>

At 20:08 2004-04-03, HJJACOBSON at AOL.COM wrote:
>I just doubt that the history of lineage-splitting can be extracted from the genome.
I understand that doubt, but I no longer agree with it. As long as the "flow" of the genome is primarily longitudinal, through the species tree, the fact that individual gene trees may not be congruent is "merely" a temporary inconvenience; eventually the pattern will become clear.
And the same could be said for morphology.