Dear ASA-o-philes -
I was struck by a passage in the recent clipping that Glenn just sent us from
_Evolution and Development_:
Rudimentary understanding of molecular biology was sufficient to spot
egregious errors, candidly dispatched by Eric Davidson. Well's claim that
aspects of *Hox* gene control, instead of providing yet more evidence for
homology and common ancestry, actually suggest that all metazoan phyla
arose independently gives the flavor of what was offered.
I'm no expert on Melecular Biology, but my mentor in that field tells me that
horizontal gene transfer has made Hox genes, and perhaps other genes, unreliable
indicators of phylogenetic affinities. She cites a classic example in which the
fruit fly, Drosophila, was found to have the "Eye" gene which controlled development
of eyes in flies. The same gene was found to control eye development in the mouse.
But an even greater surprise came to find that C. Eleganz, the nematode workhorse
animal of Biologists, also had the Eye gene, even though that animal has no eyes.
She said this strange development had to be explained by interspecies gene
transfer, which has been observed in the laboratory. This phenomenon seems to have
dimmed the bright hope that molecular affinities would enable certitude for
determining relatedness in construction of phylogenetic trees.
Perhaps there are others on the List who are Biologists and know more about this
development. It's fun to learn!
Larry
"He has made everything beautiful in its time. He has also set
eternity in the hearts of men" - - Ecclesiastes 3:11, NIV trans
================================================
Lawrence H. Johnston 917 E. 8th st.
professor of physics, emeritus Moscow, Id 83843
University of Idaho (208) 882-2765
http://www.uidaho.edu/~johnston/ =====================
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