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Turns out sharks and skates don’t need HoxC genes


File:Dipturus laevis.jpg
barndoor skate/NEFSC, NOAA
From “Study of Skates and Sharks Questions Assumptions About ‘Essential’ Genes” (ScienceDaily, Dec. 15, 2011), we learn:

Biologists have long assumed that all animals with jaws and spinal columns possess nearly identical genes that regulate critical aspects of their embryological development. But a paper in the December 16 issue of Science by Benjamin King of the Mount Desert Island Biological Laboratory (MDIBL) and three of his colleagues shows that a class of fishes that includes skates and sharks lack genes that were formerly thought to be essential for their development.

King says his work shows the importance of studying all kinds of organisms, including elasmobranchs [some sharks and skates], to understand evolution. “A goal of the field of evolutionary developmental biology is to learn how developmental processes evolved by comparing many organisms with one another,” says King. “Our work illustrates the value of studying elasmobranch fishes such as skates and sharks to gain new insights. If elasmobranchs do not need HoxC genes to develop properly, we must consider the possibility that there is more flexibility in the role of the various Hox clusters than we previously thought.”

Actually, this finding shows that there is indeed more flexibility. We must consider accepting the evidence, along with what it may imply about the history of life.

Starnge that when we see common parts used in different man-made devices we don't assume a common ancestry for the devices. PC clones-> common design Building codes-> common design Plug-n-play devices-> common design Automobile similarities-> common design IEEE-> common design We have direct observational experience with commonly designed devices and universal common descent has nothing but imagination, yet which is considered science? Joe
"Hox genes are an example of these types of nearly universal genes in organisms pointing to an origin of common ancestry." (Wikipedia)
Seems they point to common ancestry, except for elasmobranches, which arose de novo. Which is silly, so it's more likely that point mutations gradually knocked out the entire hoxc cluster whilst another basic developmental system fortunately evolved in tandem. Funny how it steered a way through purifying selection, but hey! They're here so it must have happened. An example of economy in nature - why use a universal system like screws when it's just as easy to redesign using glue? Jon Garvey

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