Predictably, Denyse O’Leary is getting all excited about a paper in this week’s Nature that finds Ctenophora (comb jellies) to be the first multicellular branch off the Tree of Life, a divergence that precedes that of the relatively simpler sponges. Apparently only accessing a LiveScience article, O’Leary breathlessly declares:
All this shock and awe comes from not taking the Avalon explosion and the Cambrian explosion of life forms seriously for what they can tell us about the real history of life, rather than the Darwinian fantasy.
Problem is, if one reads the original article, one gets a somewhat more hesitant view of things:
The placement of ctenophores (comb jellies) as the sister group to all other sampled metazoans is strongly supported in all our analyses. This result, which has not been postulated before, should be viewed as provisional until more data are considered from placozoans and additional sponges. If corroborated by further analyses, it would have major implications for early animal evolution, indicating either that sponges have been greatly simplified or that the complex morphology of ctenophores has arisen independently from that of other metazoans. [emphasis mine]
The gun. It is being jumped. Only two species of sponge (Oscarella carmella and Suberites dormuncula) were analyzed and, as the authors themselves note, Suberites has poor gene sampling which may simply provide too few informative characters for phylogenetic reconstruction. In addition, no Placozoans were analyzed. These factors - as the authors themselves note - weakens the reliability of the claim that ctenophores diverged first. Simply put, further work is required.
Here’s a suggestion, Denyse. Read the article before you pontificate, m’kay? I’m guessing they taught you something in journalism school about that.
Ref: CW Dunn et al. (2008) "Broad phylogenomic sampling improves resolution of the animal tree of life." Nature 452: 745-749. doi:10.1038/nature06614
Life Science
Comments
John, it is a journalist you're talking about!
Would they ever ruin a 'good' story with something as trivial as 'facts' or 'fact-finding'??
Posted by: shonny | April 11, 2008 3:51 AM
Being an "ARN Journalist," Denyse gets a special dispensation from doing any sort of fact-checking.
Or thinking, for that matter.
Posted by: Mike Haubrich, FCD | April 11, 2008 6:59 AM
Ctenophores are totally fucking cool. I'm very pleased that they are thought to be the first-to-diverge metazoan.
Posted by: PhysioProf | April 11, 2008 7:13 AM
They are totally f-ing cool. I used to catch them by accident all the time whilst cast-netting for shrimp at night. The dock would be littered with them and even the vibrations from walking on it would make the dock light up. They are beautiful.
Posted by: mlf | April 11, 2008 8:36 AM
Plus we know that many groups of organisms have become morphologically simpler when switching to sessile or parasitic habits. Radial symmetry is great when you are sessile.
Posted by: michaelf | April 11, 2008 1:21 PM
O'Leary wouldn't know long-branch attraction if it snapped back and smacked her in the face.
Posted by: Sven DiMilo | April 11, 2008 1:44 PM
Here's more advice for Denyse - get some training in science and critical thinking skills, and stop making your silly, baseless (and religiously biased) assertions.
It's interesting that ID can't seems to find an actual science to blog these things, but has to make do with a second-tier "journalist" who has no formal scientific training (and it shows)...
Posted by: Timcol | April 11, 2008 5:47 PM