PZ Myers posted Entry 2298 on May 23, 2006 11:07 AM.
Trackback URL: http://www.pandasthumb.org/cgi-bin/mt/mt-tb.fcgi/2293

cet_dolphin_tease.gif

I just learned (via John Lynch) about a paper on cetacean limbs that combines developmental biology and paleontology, and makes a lovely argument about the mechanisms behind the evolution of whale morphology. It is an analysis of the molecular determinants of limb formation in modern dolphins, coupled to a comparison of fossil whale limbs, and a reasonable inference about the pattern of change that was responsible for their evolution.

One important point I'd like to make is that even though what we see in the morphology is a pattern of loss—whale hindlimbs show a historical progression over tens of millions of years of steady loss, followed by a near-complete disappearance—the molecular story is very different. The main players in limb formation, the genes Sonic hedgehog (Shh), the Fgfs, and the transcription factor Hand2, are all still present and fully functional in these animals. What has happened, though, is that there have been novel changes to their regulation. Even loss of structures is a consequence of changes and additions to regulatory pathways.

Continue reading "No genes were lost in the making of this whale" (on Pharyngula)

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Comment #102010

Posted by Henry J on May 23, 2006 10:35 PM (e)

Interesting.

Henry

Comment #102076

Posted by Jason Ware on May 24, 2006 4:44 AM (e)

“By what Darwinian process did useful hind limbs wither away to vestigial proportions, and at what stage in the transformation from rodent to sea monster did this occur?” -Phillip E. Johnson in Darwin on Trial p.85

Comment #102165

Posted by fnxtr on May 24, 2006 8:54 PM (e)

Once again real research by actual scientists reveals something even more wonderful and bizarre than anything the cdesign proponentists could ever dream up.